Subject: PHASES/PITCH/BRIGHTNESS discussion From: Alexander Galembo <galembo(at)PSYC.QUEENSU.CA> Date: Sat, 21 Mar 1998 08:53:41 -0500Dear List, =20 My queries related to the influence of phase on pitch and timbre, and also the "brightness vs. pitch" problem generated a lot of responses and discussions that were very interesting and informative.=20 I would surely not be able to get all this information in another way - thanks to the list members. I had received messages asking to collect and post all the discussion materials. I did it partly once, but the discussion was not yet finished. So, I am posting it all now.=20 Alexander Galembo =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Alex Galembo Galembo(at)pavlov.psyc.queensu.ca Hi, I want to know about published and reported demonstrations of the timbral importance of the phase spectrum of a multicomponent tone.=20 I know main works, but there are not many, and I am afraid to miss anything important on the topic. I will appreciate any info. Thank you, Alexander Galembo =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Alex Galembo Dear Listers, It is classical that the pitch of a periodic complex tone is independent on phases of harmonics. I would appreciate to be informed about any publications providng a doubt in this phase independence (if exist). Thank you, Alex Galembo =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Peter Cariani Hi Alex, Several years ago I went through the literature on phase effects in conjunction with our work on population-interspike interval representations of the pitches of complex tones. Cariani, Peter A., and Bertrand Delgutte. 1996. Neural correlates of the pitch of complex tones. I. Pitch and pitch salience. II. Pitch shift, pitch ambiguity, phase-invariance, pitch circularity, and the dominance region for pitch.=20 J. Neurophysiology 76 (3) : 1698-1734. (2 papers) What I concluded from my readings was that: 0. Phase structure is much more important for nonstationary sounds (in which a particular phase structure is not repeated at some fixed recurrence time) than for stationary ones (where a particular phase structure is repeated at some fixed recurrence time, 1/F0). For nonstationary sounds, phase structure is very important for timbre (as Roy Patterson has demonstrated). 1. For stationary sounds, phase does not seem to affect the pitch of sounds with lower frequency harmonics (say below 1-2 kHz).=20 For stationary sounds, phase also does not seem to affect the timbre of sounds with lower frequency harmonics. E.g. I think it's v. hard to alter either the pitch or timbre of vowels by altering the phase spectrum. However, phase spectrum can affect the salience (strength) of the pitch that is heard. (A waveform with a higher peak factor probably generates more F0-related intervals in high-CF regions). 2. Phase has limited effects for higher frequency harmonics. Only special phase manipulations alter the pitch of such complexes, and when they do, they result in octave shifts (up). There seems to be no way that one can get arbitrary pitch shifts from phase manipulations (someone correct me if I'm wrong). In terms of interspike interval models, the intervals produced by higher frequency harmonics are related mainly to the envelopes of the cochlear filtered stimulus waveform. Phase alterations that give rise to the octave jumps do so by halving envelope= periods, thereby producing intervals at 2*F0 (or potentially, n*F0). One could think of the Flanagan-Gutman alternating polarity click trains and the Pierce tone pip experiments in these terms. For high frequency components, these phase manipulations produce envelopes with large modulations at multiples of F0, and the intervals produced follow these envelopes. In our study of pitch in the auditory nerve (above), we observed that if you consider only fibers with CF's above 2 kHz (as would be the ANF subpopulation= mainly excited by a high-pass filtered alternating click train, where these effects are most pronounced), the most frequent interspike interval corresponds to the click rate (here 2*F0) rather than the true fundamental (F0). THis corresponds with what is heard. However, if one takes the entire ANF population (all CF's), the predominant interval is always at 1/F0, which is not what is heard at low click rates (one hears a pitch at the click rate, an octave above F0). My thinking on this is that intra-channel interspike intervals may not be the whole story; that for such stimuli (esp. under high-pass filtering) strong interchannel interval patterns and synchronies are set up, and these might also play a factor in the central interval analysis. 3. Despite the largely phase-invariant nature of our perception of stationary sounds, this doesn't mean that phase isn't important. If one takes a segment of noise of 5 msec long and repeats it many times, one will hear a pitch at 200 Hz. If you scramble the phase spectrum of the noise segment in each period, you will no longer hear the repetition pitch. (One can do a similar periodicity-detection experiment with random click trains with recurrence times of seconds.) I therefore think that phase coherence is important even for those aspects of auditory perception that appear to be largely insensitive to which particular phase configuration is chosen. According to an all-order interval-based theory, one needs constant phase relations spanning at least 2 periods to preferentially create intervals related to the repetition period. There is even a more general way of thinking about detection of periodicity that involves the fusing together of phase-relations that are constant into auditory objects, and separating those relations that continually change. If we think of 2 diff. vowels with diff. F0's added together, the composite waveform contains 2 sets of internally-invariant phase relations (two periods of each vowel's waveform) plus the changing phase relations between the two vowel periods (pitch period asynchronies). If one had a means of detecting invariant phase structure, then one could separate these two auditory objects. I think Roy Patterson's strobed auditory image model moves in this direction, as do the kinds of recurrent timing models I am working on. Because of phase-locking of auditory nerve fibers, the timings of individual spike discharges provide a representation of the running stimulus phase spectrum. Interspike interval distributions are then one way of neurally representing recurrent phase relations. The formation of interval patterns depends crucially upon phase structure, but once intervals are formed, then the resulting representations are phase-independent. --Peter Cariani =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D From: B. Suresh Krishna Hi Wrt your query on the list, could you please summarize the responses and post them, or else send me a file with all the responses ? I would be very interested in the answers myself.=20 Thanks !! Suresh "B. Suresh Krishna" <suresh(at)cns.nyu.edu> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Bill Hartmann Sasha, The tone color depends on phases, but I don't know of any claim for a reliable pitch effect. =20 Because pitch is manipulable, it is likely that individual listeners get phase effects. A systematic effect might be interesting. Bill HARTMANN(at)pa.msu.edu =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Adrian Houtsma Dear Alex, Look, for instance, at Houtsma & Smurzynski, J. Acoust. Soc. Am. 87, 304, 1990. Figure 3 shows that pitch discrimination for resolved harmonics (N<10) is rather independent of phase relations (in this case sine-phase vs Schroeder-phase). For unresolved harmonics (N>10) discrimination is (1) more difficult since jnds are much larger, and (2) even more difficult for Schroeder-phase tones than for sine-phase tones. Similar evidence can be found in the dissertation of Hoekstra, cited in that paper. The general rule of thumb is: resolved harmonics > no phase sensitivity unresolved harmonics > large phase sensitivity Best wishes, Adrian Houtsma =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Shlomo Dubnov Hi, Well, it dependes what is your criteria / definition for pitch. There are works that use phase information to determine if a signal is pitch or noise (more precisely, if it is voiced or unvoiced signal in speech).=20 In case this is relevant for your question, I can provide you with= references. best, =20 --=20 Shlomo Dubnov ---------- e-mail: dubnov(at)ircam.fr =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Leslie Smith Dear Alexander: There are occasions when the phase can affect the timbre (and the =3D pitch too) when the harmonics are close together, so that they are =3D not resolved at the cochlea. Then the envelope shape (as perceived =3D at the hair cells) will depend on the phase (given 3 or more =3D harmonics). See Smith L.S. Data-driven Sound Interpretation: its Application to =3D Voiced Sounds. pp147-154, in Neural Computation and Psychology : =3D Proceedings of the 3rd Neural Computation and Psychology Workshop =3D (NCPW3), Stirling, Scotland, 31 August - 2 September 1994, editors =3D L.S. Smith and P.J.B. Hancock. Springer Verlag: Workshops in =3D Computing Series, 1995 but an earlier (and better!) reference (which I was not aware of =3D when I wrote the above) is Moore B.C.J., Effects of relative phase of the components on the =3D pitch of three-component complex tones, in Psychophysics and =3D physiology of hearing, edited by E.F. Evans and J.P. Wilson, =3D Academic Press, 1977. --leslie smith l.s.smith(at)cs.stir.ac.uk =20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: louisew(at)biols.susx.ac.uk (Louise White) Alex, Try Shackleton and Carlyon JASA 95 (6) June 1994 3529-3540 Louise louisew(at)biols.susx.ac.uk (Louise White) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Brian C. J. Moore Look at: Moore, B. C. J. (1977). Effects of relative phase of the components on the pitch of three-component complex tones. In Psychophysics and Physiology of Hearing, (ed. E. F. Evans and J. P. Wilson), pp. 349-358. Academic Press, London. Brian C. J. Moore, Ph.D. bcjm(at)pop.cus.cam.ac.uk =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D From: Richard Lyon John Pierce published in JASA about 5 years ago on some studies of signals that had pitch dependent on phase (changing by two octaves, not a small shift). And it has references to earlier work by some of his buddies at Bell (but I don't recall which ones right now). Look for him in JASA index. D =20 lyon(at)pop.ricochet.net =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Bill Schottstaedt I think John Pierce has written a couple papers on that subject: Pierce, J. R. (1990).=20 Rate, place, and pitch with tonebursts.=20 Music Perception , 7(3):205-212.=20 Pierce, J. R. (1991a ).=20 Periodicity and pitch perception.=20 Journal of the Acoustical Society of America , 90:1889-1893.=20 bil(at)ccrma.Stanford.EDU (Bill Schottstaedt) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Richard Parncutt How about... Langner, G. (1997). Temporal processing of pitch in the auditory system. Journal of New Music Research, 26, 116-132. Langner, G., & Schreiner, C.E. (1988). Periodicity coding in the inferior colliculus of the cat (I) - Neuronal mechanisms. Journal of Neurophysiology, 60, 1799-1822. Meddis, R., & Hewitt, M.J. (1991a). Virtual pitch and phase sensitivity of a computer model of the auditory periphery. Journal of the Acoustical Society of America, 89, 2866-2894. Patterson, R.D. (1973). The effects of relative phase and the number of components on residue pitch. Journal of the Acoustical Society of America, 53, 1565-1572. That reminds me! I'd be grateful for brief, private, independent assessment of Langner's work. Richard Parncutt, Email: r.parncutt(at)keele.ac.uk.=20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Bob Carlyon Prof. Galembo, Trevor Shackleton and I did some experiments showing that, compared to a sine-phase stimulus, and alternating-phase stimulus has a pitch about 1 octave higher, provided that its harmonics are unresolved by teh peripheral auditory system. We also review earlier papers showing similar pitch-doubling effects. The article is published in jasa vol 95 p3529-3540 (1994) regards bob carlyon email: bob.carlyon(at)mrc-apu.cam.ac.uk =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Malcolm Slaney At 6:28 AM -0800 2/4/98, Alexander Galembo wrote: >I would appreciate to be informed about any publications providng a doubt >in this phase independence (if exist). I think the first were Flanagan and Guttman (1960). I'm not sure if they described their observations as a phase change, but they are. Pierce, a few years ago, redid the experiments. A description of this stimulai that Richard Duda wrote for the Apple Hearing Demo Reel is appended to the end of my note. Malcolm This animation was produced in conjunction with Richard Duda of the Department of Electrical Engineering at San Jose State University during the Summer of 1989. Thanks to Richard Duda for both the audio examples and the explanation that follows and to John Pierce for calling this experiment to our attention. Researchers in psychoacoustics have long looked to cochlear models to explain the perception of musical pitch [Small70]. Many experiments have made it clear that the auditory system has more than one mechanism for pitch estimation. In one of these experiments, Flanagan and Guttman used short-duration impulse trains to investigate two different mechanisms for matching periodic sounds, one based on spectrum and one based on pulse rate [Flanagan60]. They used two different impulse trains, one having one pulse per period of the fundamental, the other having four pulses per period, every fourth pulse being negative . These signals have the interesting property that they have the same power spectrum, which seems to suggest that they should have the same pitch. The standard conclusion, however, was that below 150 pulses per second the trains "matched" if they had the same pulse rate; they "matched" on spectrum only when the fundamental frequency was above about 200 Hz. [Pierce89] modified this experiment by replacing the pulses by tone bursts=F3short periods of a 4,800-Hz sine wave modulated by a raised-cosine Hamming window. In essence, he used Flanagan and Guttman's pulses to amplitude modulate a steady high-frequency carrier. His purpose in doing this was to narrow the spectrum, keeping the large response of the basilar membrane near one place (the 4,800-Hz place), regardless of pulse rate. To be more specific, Pierce used the three signal "patterns" shown below. All have the same burst duration, which is one-eighth of a pattern period. Pattern a has four bursts in a pattern period. Pattern b has the same burst rate or pulse rate, but every fourth burst is inverted in phase. Thus, the fundamental frequency of b is a factor of four or two octaves lower than that of a. Pattern c has only one burst per pattern period, and thus has the same period as b; in fact, it can be shown that b and c have the same power spectrum. Thus, a and b sound alike at low pulse rates where pulse-rate is dominant, and b and c sound alike at high pulse rates where spectrum is dominant. Pierce observed that the ear matches a and b for pattern frequencies below 75 Hz, and matches b and c for pattern frequencies above 300 Hz. He found the interval between 75 and 300 Hz to be ambiguous, the b pattern being described as sounding inharmonic. Pierce's tone bursts. Patterns a and b have the same pulse rate frequency, while b and c have the same power spectrum. Here the test sounds are shown with one cycle per burst. To see if and how these results are reflected in correlograms, a similar set of tone burst signals were generated. The only difference between our signals and Pierce's signals was due to differences in the digital sampling rate used. To get a Fourier spectrum with minimum spectral splatter, Pierce imposed two requirements: 1)The tone-burst frequency fb was set at half the Nyquist rate. Where Pierce's 19,200-Hz sampling rate led to fb =3D 4,800 Hz, our 16,000-Hz sampling rate forced fb down to 4,000 Hz. 2)Each burst had to contain an exact integral number n of cycles. This number, n, is a major parameter for the experiments, ranging from 1 to 128. If the pattern period is T, then to obtain exactly n cycles of frequency fb in time T/8 requires that fb T/8 =3D n, so that T =3D 8n/fb . Thus, to obtain the same spectral characteristics, we had to use different numerical values for the tone-burst frequency fb and the corresponding pattern period T. The table shown below is our version of Table I in Pierce's paper. A set of eight test signals was generated according to this scheme. Each test signal consists of a sequence of the a, b and c patterns, each pattern lasting 1.024 seconds. This time interval was chosen to get an exact integer number of bursts, ranging from 4 for Case 1c to 2000 for Cases 8a and 8b. Malcolm Slaney malcolm(at)interval.com =3D-=3D=3D=3D=3D=3D=3D From: "R. Parncutt" <psa03(at)CC.KEELE.AC.UK> Subject: effect of phase on pitch Pondering the evolutionary origins of the ear's "phase deafness" in most naturally occurring sounds, I have come up with the following argument. Does it make sense? Is there other literature on this subject that I have missed? ::: In everyday listening environments, phase relationships are typically jumbled unrecognizably when sound is reflected off environmental objects; that is, when reflected sounds of varying amplitudes (depending on the specific configuration and physical properties of the reflecting materials) are added onto sound traveling in a direct line from the source. Thus, phase information does not generally carry information that can reliably aid a listener in identifying sound sources in a reverberant environment (Terhardt, 1988; see also Terhardt, 1991, 1992). This is a matter of particular concern in an ecological approach, as non-reverberant environments are almost non-existent in the real world (anechoic rooms, mountain tops). On the other hand, again in real acoustic environments, spectral frequencies (that is, the frequencies of isolated components of complex sounds, or clear peaks in a running spectrum, forming frequency trajectories in time-varying sounds) cannot be directly affected by reflection off, or transmission through, environmental obstacles. They might be indirectly affected as a byproduct of the effect that such manipulations can have on amplitudes (e.g., a weakly defined peak could be pushed sideways if amplitudes increased on one side and decreased on the other), but such phenomena could hardly affect audible sound spectra. So for the auditory system to reliably identify sound sources, it needs to ignore phase information, which is merely a constant distraction, and focus as far as possible on a signal's spectral frequencies (and to a lesser extent on the relative amplitudes of individual components, keeping in mind that these, too, are affected by reflection and transmission). The ear's phase deafness with regard to pitch perception is thus a positive attribute. In fact, it may be regarded as an important phylogenetic achievement - the result of a long evolutionary process in which animals whose ears allowed phase relationships to interfere with the identification of dangerous or otherwise important sound sources died before they could reproduce. If this scenario is correct, then it is no surprise that we are highly sensitive to small changes in frequency, and highly insensitive to phase relationships within complex sounds. Straightforward evidence of the ear's insensitivity to phase in the sounds of the real human environment has been provided by Heinbach (1988). He reduced natural sounds including speech (with or without background noise and multiple speakers) and music to their spectral contours, which he called the part-tone-time-pattern. In the process, he completely discarded all phase information. The length of the spectrum analysis window was carefully tuned to that of the ear, which depends on frequency. Finally, he resynthesized the original sounds, using random or arbitrary phase relationships. The resynthesized sounds were perceptually indistinguishable from the originals, even though their phase relationships had been shuffled. It is nevertheless possible to create artificial stimuli for which clear, significant perceptual effects of phase relationships on perception can be demonstrated. For example, Patterson (1973, 1987) demonstrated that listeners can discriminate two harmonic complex tones on the basis of phase relationships alone. Moore (1977) demonstrated that the relative phase of the components affects the pitch of harmonic complex tones consisting of three components; for each tone, there were several possible pitches, and relative phase affected the probability of a listener hearing one of those as 'the' pitch. Hartmann (1988) demonstrated that the audibility of a partial within a harmonic complex tone depends on its phase relationship with the other partials. Meddis & Hewitt (1991b) succeeded in modeling these various phase effects, which (as Moore, 1977, explained) generally apply only to partials falling within a single critical band or auditory filter. In an ecological approach, the existence of phase sensitivity in such stimuli (or such comparisons between stimuli) might be explained as follows. These stimuli (or stimulus comparisons) do not normally occur in the human environment. So the auditory system has not had a chance to'learn' (e.g., through natural selection) to ignore the phase effects. As hard as the ear might 'try' to be phase deaf in the above cases, some phase sensitivity will always remain, for unavoidable physiological reasons. There could, however, be some survival value associated with the ability to use phase relationships to identify sound sources during the first few tens of ms of a sound, before the arrival of interference from reflected waves in typical sound environments. On this basis, we might expect phase relationships at least to affect timbre, even in familiar sounds. Supporting evidence for this idea in the case of synthesized musical instrument sounds has recently been provided by Dubnov & Rodet (1997). In the case of speech sounds, Summerfield & Assmann (1990) found that pitch-period asynchrony aided in the separation of concurrent vowels; however, the effect was greater for less familiar sounds (specifically, it was observed at fundamental frequencies of 50 Hz but not 100 Hz). In both cases, phase relationships affected timbre but not pitch. The model of Meddis & Hewitt (1991a) is capable of accounting for known phase dependencies in pitch perception (Meddis & Hewitt, 1991b). This raises the question: why might it be necessary or worthwhile to model something that does not have demonstrable survival value for humans (whereas music apparently does have survival value, as evidenced by the universality of music in human culture). As Bregman (1981) pointed out, we need to "think about the problems that the whole person faces in using the information available to his or her sense organs in trying to understand an environment" (p. 99). From this point of view, the human ear might be better off without any phase sensitivity at all. Bregman goes on to say that "Because intelligent machines are required actually to work and to achieve useful results, their designers have been forced to adopt an approach that always sees a smaller perceptual function in terms of its contribution to the overall achievement of forming a coherent and useful description of the environment." So if one were building a hearing robot, there would be no point in incorporating effects of phase on pitch perception, if such effects did not help the robot to identify sound sources. Bregman, A.S. (1981). Asking the 'What for?' question in auditory perception. In M. Kubovy & J. R. Pomerantz (Eds.), Perceptual organization (pp. 99-118). Hillsdale, N.J. Dubnov, S., & Rodet, X. (1907). Statistical modeling of sound aperiodicities. Proceedings of the International Computer Music Conference, Thessaloniki, Greece, (pp. 43-50). Hartmann, W. (1988). Pitch perception and the segregation and integration of auditory entities. In G. M. Edelman, W. E. Gall, & W. M. Cowan (Eds.), Auditory function (pp. 623-645). New York: Wiley. Heinbach, W. (1988). Aurally adequate signal representation: The Part-Tone-Time-Pattern. Acustica, 67, 113-121. Meddis, R., & Hewitt, M.J. (1991a). Virtual pitch and phase sensitivity of a computer model of the auditory periphery. I: Pitch identification. Journal of the Acoustical Society of America, 89, 2866-2882. Meddis, R., & Hewitt, M.J. (1991b). Virtual pitch and phase sensitivity of a computer model of the auditory periphery II: Phase sensitivity. Journal of the Acoustical Society of America, 89, 2883-2894. Moore, B.C.J. (1977). Effects of relative phase of the components on the pitch of three-component complex tones. In E. F. Evans & J. P. Wilson (Eds.), Psychophysics and physiology of hearing (2nd ed.) (pp. 349-362). New York: Academic. Patterson, R.D. (1973). The effects of relative phase and the number of components on residue pitch. Journal of the Acoustical Society of America, 53, 1565-1572. Patterson, R.D. (1987). A pulse ribbon model of monaural phase perception. Journal of the Acoustical Society of America, 82, 1560-1586. Summerfeld, Q., & Assmann, P. F. (1990). Perception of concurrent vowels: Effects of harmonic misalignment and pitch-period asynchrony. Journal of the Acoustical Society of America, 89, 1364-1377. Terhardt, E. (1988). Psychoakustische Grundlagen der Beurteilung musikalischer Kl nge. In J. Meyer (Ed.), Qualit tsaspekte bei Musikinstrumenten (pp. 9-22). Celle: Moeck. Terhardt, E. (1991). Music perception and sensory information acquisition: Relationships and low-level analogies. Music Perception, 8, 217-240. Terhardt, E. (1992). From speech to language: On auditory information processing. In M. E. H. Schouten (Ed.), The auditory processing of speech (p. 363-380). Berlin: Mouton de Gruyter. Richard Parncutt ------------------------------------- From: "PETER B.L. Meijer" <meijer(at)NATLAB.RESEARCH.PHILIPS.COM> Subject: Re: effect of phase on pitch February 5, 1998 Richard Parncutt wrote a very interesting discussion / essay on "phase deafness", and seems to make a distinction between artificial and natural sounds > In an ecological approach, the existence of phase sensitivity in such > stimuli (or such comparisons between stimuli) might be explained as= follows. > These stimuli (or stimulus comparisons) do not normally occur in the human > environment. So the auditory system has not had a chance to'learn' (e.g., > through natural selection) to ignore the phase effects. As hard as the ear > might 'try' to be phase deaf in the above cases, some phase sensitivity= will > always remain, for unavoidable physiological reasons. I have a complex-sound generating application, so far based on my assumption that phases may be neglected: phases are random. Also, the sound components are normally not harmonic, so any momentary phase relations will change over time. However, these sounds, derived from spectrographic synthesis of environmental images instead of spectrographic (re)synthesis of spectrograms, definitely ``do not normally occur in the human environment,'' and involve both ``tens of ms'' bursts as well as sounds of much longer duration. So, should or should I not have tried to exploit phase sensitivity and enforce certain, e.g., short-term, phase relations? Or should I hope (in vain?) that people can "un-learn" to hear most of the (if any) phase effects? Any advice? See http://ourworld.compuserve.com/homepages/Peter_Meijer/winvoice.htm for the video sonification application I refer to. In other words, my question relates to how to optimize auditory perception / resolution in complex information-carrying sounds, and I wonder if I should "do something" with phases or not. There is non-evolutionary survival value at stake here. Best wishes, Peter Meijer =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Bert Schouten <Bert.Schouten(at)LET.RUU.NL> Subject: Re: effect of phase on pitch Perceptual effects of phase on pitch or timbre could be epiphenomena of a mechanism needed for sound localization. We need some form of phase-locking in the auditory nerve in order to be able to compare the signals from the two ears. In natural environments the ear receives no phase information about the sound source, so pitch and timbre cannot normally be based on temporal information, but the sensitivity to temporal differences between the two ears may influence pitch or timbre whenever headphones are used or when phones are inserted into animals' ear canals. I agree, therefore, with Richard Parncutt's evaluation of the lack of relevance of phase information for pitch and timbre, but I prefer an epiphenomenal rather than a phylogenetic explanation for any residual effects. I am looking askance now at Peter Cariani, with whom I have had this argument before. Bert Bert Schouten (M.E.H.) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: LASZLO Toth <tothl(at)INF.U-SZEGED.HU> X-To: auditory(at)vm1.mcgill.ca To: Multiple recipients of list AUDITORY <AUDITORY(at)VM1.MCGILL.CA> >From tothl Thu Feb 5 16:50:04 +0100 1998 remote from inf.u-szeged.hu Date: Thu, 5 Feb 1998 16:50:04 +0100 (MET) From: Toth Laszlo <tothl(at)inf.u-szeged.hu> X-Sender: tothl(at)csilla To: Multiple recipients of list AUDITORY <AUDITORY(at)VM1.MCGILL.CA> Subject: Re: effect of phase on pitch Message-ID: <Pine.SV4.3.91.980205162120.6492F-100000(at)csilla> MIME-Version: 1.0 Received: from inf.u-szeged.hu by inf.u-szeged.hu; Thu, 5 Feb 1998 16:50= MET Content-Type: TEXT/PLAIN; charset=3DUS-ASCII Content-Length: 1754 On Thu, 5 Feb 1998, R. Parncutt wrote: > ... > Straightforward evidence of the ear's insensitivity to phase in the sounds > of the real human environment has been provided by Heinbach (1988). He > reduced natural sounds including speech (with or without background noise > and multiple speakers) and music to their spectral contours, which he= called > the part-tone-time-pattern. In the process, he completely discarded all > phase information. The length of the spectrum analysis window was= carefully > tuned to that of the ear, which depends on frequency. Finally, he > resynthesized the original sounds, using random or arbitrary phase > relationships. The resynthesized sounds were perceptually= indistinguishable > from the originals, even though their phase relationships had been= shuffled. > "Perceptually indistinguishable" means here only that their PITCHes were perceptually indistingushable, am I right? Considering other aspects, changing the phase relationships definitely has effects on sound quality. In phase vocoders, for example, uncorrect decoding of phases results in really annoying artifacts. Toth Laszlo =20 e-mail: tothl(at)inf.u-szeged.hu =20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Peter Cariani <peter(at)epl.meei.harvard.edu> Subject: Re: effect of phase on pitch R. Parncutt wrote: > Pondering the evolutionary origins of the ear's "phase deafness" in most > naturally occurring sounds, I have come up with the following argument.= Does > it make sense? Is there other literature on this subject that I have= missed? I definitely agree that the auditory system is essentially phase-deaf,except around the edges (which is why the edges are interesting). However, where we would differ is I think that it is possible that the phase-deafness of the system is a result of interspike interval analyses and mechanisms that integrate/fuse invariant phase relationships into unified objects, whereas you would hold that this system is phase deaf because it uses rate-place representations. Is this fair?=20 >In everyday listening environments, phase relationships are typically=20 > jumbled unrecognizably when sound is reflected off environmental objects; > that is, when reflected sounds of varying amplitudes (depending on the > specific configuration and physical properties of the reflecting= materials) > are added onto sound traveling in a direct line from the source. Thus,= phase > information does not generally carry information that can reliably aid a > listener in identifying sound sources in a reverberant environment > (Terhardt, 1988; see also Terhardt, 1991, 1992). Let's consider an echo off one surface that introduces a time delay. To the extent that the echo's time pattern resembles that of the original stimulus, depending upon the delay between the two the sound and its echo can be fused into one object. In an ecological situation, sound reflecting surfaces and their properties are not changing rapidly. The phase structure of echoes combined with the phase structure of the direct sound will then form an invariant whole, so that if one has a mechanism for fusing together repeated relative phase patterns, echoes become fused with the direct signal (i.e. fusion is a dfferent strategy for "echo suppression"). At short delays (<15 msec) one hears only one sound; at longer delays the timbre of the one sound changes, and at really long delays one hears two sounds. These differences would be related to how the auditory system integrates recurrent patterns with different delays. In such situations, one would not generally be able to distinguish one particular phase pattern from another, but it would be important that the time structure of the signal and that of the echo be largely similar in order for fusion to take place. I don't think things get much more Gibsonian than this. If the auditory system operates this way, then there is an invariant time pattern in the sound environment that the sound and the echo share that is extracted by the auditory system. One way to think about this is that the auditory system brings the correlation structure of sound & echo into the nervous system by means of phase- locked discharges. This phase-locking is seen in every sensory system, albeit on different time scales, so stimulus-driven time structure has been around at least as long as sensory receptors and sensory neurons. Essentially, if the fine structure of the stimulus is present in the timings of discharges, then it is possible to carry out very, very general kinds of pattern recognition operations that extract invariant time structure from what amounts to an analog, iconic representation of the sound.=20 This is much closer to Gibsonian ideas concerning mechanisms of perception than models based on spectral features (perceptual atoms) and complex pattern recognitions.=20 >This is a matter of particular concern in an ecological approach, as=20 >non-reverberant environments are almost non-existent in the real world >(anechoic rooms, mountain tops). On the other hand, again in real acoustic >environments, spectral frequencies (that is, the frequencies of isolated >components of complex sounds, or clear peaks in a running spectrum, forming >frequency trajectories in time-varying sounds) cannot be directly affected by > reflection off, or transmission through, environmental obstacles. They= might > be indirectly affected as a byproduct of the effect that such= manipulations > can have on amplitudes (e.g., a weakly defined peak could be pushed= sideways > if amplitudes increased on one side and decreased on the other), but such > phenomena could hardly affect audible sound spectra. > So for the auditory system to reliably identify sound sources, it needs to > ignore phase information, which is merely a constant distraction, and= focus > as far as possible on a signal's spectral frequencies (and to a lesser > extent on the relative amplitudes of individual components, keeping in= mind > that these, too, are affected by reflection and transmission). In a sense we are saying similar things here.=20 Interspike interval distributions, like rate-place profiles, are both "phase-deaf" representations, and form analysis is based on such basic "phase-deaf" representations. >The ear's phase deafness with regard to pitch perception is thus a positive= =20 > attribute. In fact, it may be regarded as an important phylogenetic >achievement - the result of a long evolutionary process in which animals whose >ears allowed phase relationships to interfere with the identification of >dangerous or otherwise important sound sources died before they could >reproduce. If this scenario is correct, then it is no surprise that we are >highly sensitive to small changes in frequency, and highly insensitive to phase >relationships within complex sounds. Localization of sound is important, but it is no less important to be able to recognize the forms of sounds, to be able to distinguish and recognize different sound sources. The reason that we talk so much in terms of localization is that we understand more of how localization mechanisms operate: what are the cues, what are the neural computations. One could make an analogous argument that it is important to be able to detect arbitrary recurring sound patterns that come in at different times, and that therefore basic mechanisms evolved that integrate similar time patterns over many delays. Such mechanisms would be deaf to the particular phases of sounds, but sensitive to transient changes in phase structure. Birds and humans detect mistuned harmonics quite well. Why is this? The harmonic complex has a constant phase structure that recurs from period to period and the mistuned component has a constant phase structure that recurs at its own unrelated period.=20 Phase relations between the complex and the mistuned component are constantly changing. Two sounds are heard because invariant waveform/phase patterns are fused together and varying sets of relations are separated. Similar kinds of considerations apply to double vowels with different F0's.=20 > Straightforward evidence of the ear's insensitivity to phase in the sounds > of the real human environment has been provided by Heinbach (1988). He > reduced natural sounds including speech (with or without background noise > and multiple speakers) and music to their spectral contours, which he= called > the part-tone-time-pattern. In the process, he completely discarded all > phase information. The length of the spectrum analysis window was= carefully > tuned to that of the ear, which depends on frequency. Finally, he > resynthesized the original sounds, using random or arbitrary phase > relationships. The resynthesized sounds were perceptually= indistinguishable > from the originals, even though their phase relationships had been= shuffled. Yes, but these sounds still had the same time-pattern within each freq. channel and the relations of time-patterns across channels were presumably stable over the course of the stimulus. If the interchannel phase relations were constantly changing, I think the sound would not have the same quality. If you introduced many random delays at different timepoints into the different frequency channels, I would think that these sounds would break apart. I've experimented with sequences of vowel periods having different phase relationships. One can take the waveform of a vowel period and flip its polarity and/or reverse it in time. This results in 4 possible operations for each vowel period. If you do this in an orderly, regular, repeating way, the resulting waveform has a pitch corresponding to the recurrence period of the whole pattern. If you randomize the sequences, the waveform has a very noisy pitch and has a very different quality, and if you introduce random time delays in between the vowel periods in addition to the random phase switches, the pitch goes away.=20 Now the short-term spectral structure of this sound is constant, but the time-relations between events in one vowel period and another have been destroyed. Voice pitches of vowels thus can be seen as the result of recurrent phase patterns that span vowel periods. It is the delay between the patterns (the recurrence time) that determines the pitch. If there are no recurrent phase patterns there is no pitch. Recurrence time of phase (time interval) defines frequency.=20 > It is nevertheless possible to create artificial stimuli for which clear, > significant perceptual effects of phase relationships on perception can be > demonstrated. For example, Patterson (1973, 1987) demonstrated that > listeners can discriminate two harmonic complex tones on the basis of= phase > relationships alone. I think that this discrim. was on the basis of a timbre difference. I agree that phase relations can in some cases alter the relative influence of particular harmonics and thereby influence timbre. > Moore (1977) demonstrated that the relative phase of the components affects >the pitch of harmonic complex tones consisting of three components; for each >tone, there were several possible pitches, and relative phase affected the >probability of a listener hearing one of those as 'the' pitch. These several possible pitches, I assume, were associated with partials that could be heard rather than with F0. Again phase structure can subtly alter the relative salience of particular harmonics, and hence the partials that are best heard. > Hartmann (1988) demonstrated that the audibility of a=20 > partial within a harmonic complex tone depends on its phase relationship > with the other partials. Yes. > Meddis & Hewitt (1991b) succeeded in modeling these > various phase effects, which (as Moore, 1977, explained) generally apply > only to partials falling within a single critical band or auditory filter. I think what happens is that relative phase can affect which harmonic is most effective at creating discharges that are phase-locked to it. > In an ecological approach, the existence of phase sensitivity in such > stimuli (or such comparisons between stimuli) might be explained as= follows. > These stimuli (or stimulus comparisons) do not normally occur in the human > environment. So the auditory system has not had a chance to'learn' (e.g., > through natural selection) to ignore the phase effects. As hard as the ear > might 'try' to be phase deaf in the above cases, some phase sensitivity= will > always remain, for unavoidable physiological reasons. But these effects are all extremely subtle. I don't think vowel quality ever changes so radically that one hears a completely different vowel. But why are there these kinds of subtle effects at all? >From a rate-perspective, one could argue for some kind of slight rate-suppression that depended on relative phases of closely spaced harmonics. The interval account would be similar, except that instead of rate suppression, one would have interval or synchrony suppression. > There could, however, be some survival value associated with the ability= to > use phase relationships to identify sound sources during the first few= tens > of ms of a sound, before the arrival of interference from reflected waves= in > typical sound environments. On this basis, we might expect phase > relationships at least to affect timbre, even in familiar sounds.= Supporting > evidence for this idea in the case of synthesized musical instrument= sounds > has recently been provided by Dubnov & Rodet (1997). In the case of speech > sounds, Summerfield & Assmann (1990) found that pitch-period asynchrony > aided in the separation of concurrent vowels; however, the effect was > greater for less familiar sounds (specifically, it was observed at > fundamental frequencies of 50 Hz but not 100 Hz). In both cases, phase > relationships affected timbre but not pitch. > The model of Meddis & Hewitt (1991a) is capable of accounting for known > phase dependencies in pitch perception (Meddis & Hewitt, 1991b). This= raises > the question: why might it be necessary or worthwhile to model something > that does not have demonstrable survival value for humans (whereas music > apparently does have survival value, as evidenced by the universality of > music in human culture). It's certainly premature to judge what kinds of auditory representations have or don't have "demonstrable survival value for humans." Phase dependencies may be side issues in ecological terms, but they do shed light on basic auditory mechanisms.=20 Deciding what is evolutionarily-relevant is difficult at best. In arguing that music perception is culturally universal, therefore it must have survival value, I think one commits an evolutionary fallacy, that every capability is the result of a particular adaptation to a particular ecological demand.=20 Even Steven Pinker doesn't go this far. At least he would say that music perception could be a by-product of other adaptations. It's very hard indeed to identify what the inherent survival value of music would be. And there can be generalist evolutionary strategies and general-purpose pattern recognizers, so that it is not always the case that evolutionary demands and solutions have to be so parochial....... (most of vision isn't face recognition, even if one thinks that face recognition is a special purpose module selected for a special-purpose ecological demand -- we see all sorts of complex patterns that our evolutionary forebears never encountered. We were not evolutionarily selected to read text such as this, but we can do it because our visual mechanisms have sufficient generality that we can learn to recognize letters and words). I'd rather we avoid particularistic adaptive "just-so" stories to explain away peculiarities of our senses. However, studying music perception is very important even if music had/has no inherent survival value for the species, because it gives us another window on complex modes of auditory representation and processing. Music is an important aspect of auditory cognition, and your work on the structure of auditory cognition is quite valuable regardless of whether music is essential to survival.=20 Very general kinds of pattern recognition mechanisms are possible and could very well be based on the nature of the basic auditory representations. For example, if an all-order interval analysis is carried out by the central auditory system, the harmonic relations (octaves, fifths, low-integer frequency ratios) all fall out of the inherent harmonic structure of time intervals and their interactions. (I've read your book and know you don't like these kinds of Pythagorean relations. But there they are.......) Our perception of octave similarities would be the result of very basic similarities in interval representations rather than the result of acquired associations. According to this perspective, octave-similarities and perception of missing fundamentals are the consequence of the operation of phylogenetically-ancient neural coding systems. We may be phase-deaf, but much of our auditory perception may be based on phase-locking nonetheless.=20 -- Peter Cariani =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: "Steven M. Boker" <sboker(at)CALLIOPE.PSYCH.ND.EDU> Subject: Re: effect of phase on pitch X-To: AUDITORY(at)VM1.MCGILL.CA To: Multiple recipients of list AUDITORY <AUDITORY(at)VM1.MCGILL.CA> Bert Schouten <Bert.Schouten(at)LET.RUU.NL> writes: >Perceptual effects of phase on pitch or timbre could be epiphenomena >of a mechanism needed for sound localization. We need some form of >phase-locking in the auditory nerve in order to be able to compare >the signals from the two ears. In natural environments the ear >receives no phase information about the sound source, so pitch and >timbre cannot normally be based on temporal information, but the >sensitivity to temporal differences between the two ears may >influence pitch or timbre whenever headphones are used or when >phones are inserted into animals' ear canals. > This argument seems almost right, although I'd add that phase information is highly predictive of self-motion. Thus there may be a strong localization component of phase both for objects and for self-location within the frame of reference. Similarly, phase change is correlated with object acceleration within an environment. If an sound source starts to move toward the listener and there is a reflecting wall behind the sound source, both the sound source acceleration and the acceleration of the source relative to the wall would be predictable from the phase changes of the direct and the reflected sound. There is some research (see Stoffrengen's recent paper for an overview) into perception of self motion through auditory cues. I argue that a large proportion of that information is contained in phase. However, if we are to maintain Pitch Constancy (similar to color constancy) for moving objects, phase changes must be removed from the perception of pitch and relegated to motion detection. There is some error in this process. The error can be most readily seen in an environment where the subject is wearing headphones, because then the phase changes are decoupled from the other sensory modes of information about self-motion. It is partly this multi-modal self motion information that allows the phase information to be removed from the incoming auditory signal and pitch constancy to be attained. Cheers, Steve Steven M. Boker 219-631-4941 (office) sboker(at)nd.edu 219-631-8883 (fax) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D From: Michael Kubovy <mk9y(at)virginia.edu> Organization: University of Virginia, Department of Psychology Subject: Re: effect of phase on pitch Please note the following sorely neglected article, which shows that when= one hears a twelve-component uniform-amplitude harmonic complex in cosine phase= in which a single component has been shifted out of cosine phase, the singular component segregates from the complex. At the same time, however, the pitch of the fundamental does not seem to be affected. The article also shows that if one passes the waveform of such a complex through a square-root or cubic-root compressive transformation, the spectrum of the resulting waveform has a= peak at the frequency of the singular component. article{kubovy79, author =3D {Kubovy, M and Jordan, R}, title =3D {Tone-segregation by phase: On the phase sensitivity of the single ear}, journal =3D {Journal of the Acoustical Society of America}, volume =3D 66, number =3D 1, pages =3D {100--106}, year =3D = 1979,} Some aspects of this work were followed up in: (at)phdthesis{Daniel86, author =3D {Jane Elizabeth Daniel}, title =3D {Detecting spectral and temporal differences in the harmonic complex}, school =3D {Rutgers University, New Brunswick, NJ}, year =3D 1986, note =3D {available from Rutgers's Library of Science and Medicine, BF.D184 1986},} Michael Kubovy, Professor of Psychology Dept. of Psychology, Univ. of Virginia =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: B. Suresh Krishna Thanks a lot !! For forwarding the responses and for asking the question .= =20 Suresh B. Suresh Krishna Email: suresh(at)cns.nyu.edu=20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Alex Galembo Dear List, I would appreciate anybody to direct me to the publications describing how gradual increase of the brightness of the tone might increase errors in pitch estimation or evoke pitch shift. Once more, thanks a lot to all who participated in the discussion on phase influence on pitch that was very useful for me and as I know for some other listers.=20 Alex Galembo =3D=3D=3D=3D=3D=3D=3D=3D=3D From: "James W. Beauchamp" <jwb(at)timbre.music.uiuc.edu> To: galembo(at)psyc.queensu.ca Subject: your info request Alex, ... I don't know of any publications which have conducted psychoacoustic tests about brightness changing to a pitch change judgement. The results could be highly dependent on individual subjects. For example, if you gradually remove the even harmonics of a sawtooth tone, at what point does one=20 report the pitch to be an octave higher? This must have to do with= thresholds. But it also has to do with listener expectation. ... Jim =3D=3D=3D=3D=3D=3D=3D=3D From: "R. Parncutt" <psa03(at)cc.keele.ac.uk> Subject: Re: your mail To: galembo(at)psyc.queensu.ca Date: Fri, 13 Feb 1998 13:27:20 +0000 (GMT) X-Mailer: ELM [version 2.4 PL23] > I would appreciate anybody to direct me to the publications decribing how > gradual increase of the brightness of the tone might increase errors in > pitch estimation or evoke pitch shift. Terhardt's model would predict the pitch shift but I'm not sure how plausible the predictions would be... Best wishes, Richard Parncutt, Lecturer in Psychology of Music and Psychoacoustics, Unit for the Study of Musical Skill and Development, Keele University. Post: Dept of Psychology, Keele University, Staffordshire ST5 5BG, GB. Tel: 01782 583392 (w),01782 719747 (h). Email: r.parncutt(at)keele.ac.uk.=20 Fax: +44 1782 583387. URL: http://www.keele.ac.uk/depts/ps/rpbiog.htm. =3D=3D=3D=3D=3D=3D=3D=3D=3D From: Punita Singh I have run into this phenomenon several times -- where the spectral locus of components in a complex (correlated with timbral "sharpness" or "brightness") affects judgments of pitch. For details re: pitch discrimination affected by changes in spectral locus, see: Singh, P.G. and Hirsh, I.J. (1992) "Influence of spectral locus and F0 changes on the pitch and timbre of complex tones", J. Acoust. Soc. Am., 92(5), 2650-2661. For interactions between brightness and pitch observed in a sequential grouping context, see: Singh, P.G. (1987) "Perceptual organization of complex-tone sequences: A tradeoff between pitch and timbre?" Both these papers contain other relevant references as well. Another reference which comes to mind, is a chapter by Hesse on judgment of musical intervals in the book "Music, mind and brain" Manfred Clynes (ed.), Plenum, 1983-- which showed some interaction between pitch judgments and brightness. My 1990 Ph. D. dissertation from Washington University, St. Louis, on "Perceptual correlates of spectral changes in complex tones" also contains several references on this topic (prior to 1990) ! Punita =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Punita Singh From: Punita Singh <pgsingh(at)HOTMAIL.COM> Subject: Re: Brightness affecting pitch X-To: AUDITORY(at)VM1.MCGILL.CA To: Multiple recipients of list AUDITORY <AUDITORY(at)VM1.MCGILL.CA> OOOOPS! I wanted to pitch in, but my lack of brightness interfered .. Here are the Miss Singh details for the second reference: > >For interactions between brightness and pitch observed in a sequential grouping context, see: > Singh, P.G. (1987) "Perceptual organization of complex-tone >sequences: A tradeoff between pitch and timbre?" J. Acoust. Soc. Am. 82(3), 886-899. Re: the diss, - it can be borrowed from the library at Washington University, St. Louis, via inter-lib loan, or can be ordered from UMI at 1-800-521-0600, order no. 9122399. >"Perceptual correlates of spectral changes in complex tones" (1990) --- Punita =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Al Bregman <bregman(at)hebb.psych.mcgill.ca> Subject: Re: your mail X-To: Alexander Galembo <galembo(at)psyc.queensu.ca> X-cc: Roger Shepard <ROGER(at)PSYCH.STANFORD.EDU>, Carol Krumhansl <clk4(at)cornell.edu>, John Pierce <JRP(at)CCRMA.STANFORD.EDU>, Auditory list <auditory(at)vm1.mcgill.ca> To: Multiple recipients of list AUDITORY <AUDITORY(at)VM1.MCGILL.CA> Dear Alexander, Let me reply to your query about anomalies in pitch perception by sandwiching my replies in between parts of your text. I hope you will not mind my sending a copy to the AUDITORY list for comments and to the colleagues that I mention below: According to many music psychologists (Shepard, Krumhansl) there are two aspects to "pitch", namely "pitch height" and "chroma". "Pitch height" refers to the up-down dimension of pitch (e.g., the difference between A440 and A880). "Chroma" refers to the circular dimension, in which pitches repeat again in every octave. I think brightness might be related to pitch height. Galembo: > ... However, the pitch height dimension is not determined well [enough] > to measure it. > The known unit is an octave, but what about fractions of the pitch- > height octave? Bregman: Since pitch height is a psychological property, not a physical one, any measurement would have to come out of a multidimensional scaling. Perhaps the best people to talk to about this would be: Roger Shepard <ROGER(at)PSYCH.STANFORD.EDU>, Carol Krumhansl <clk4(at)cornell.edu> Galembo: > For example, I have a bass A1 tone with equal amplitudes and all-sine > phases of 100 harmonics, and another tone having alternate sine-cosine > phases of the odd and even harmonics correspondingly. When directly > compared, the second tone is sounding for some subjects an octave higher > than the first. (This result corresponds, to some extent, to the finding= by > Carlyon and Shackleton related to higher unresolvable harmonics of the > middle range fundamentals, published in JASA 95, 3529 (1994)). > But this "A1-A1 octave" interval is not "strong" and might be judged in > other situations as just increased brightness. > If to compare the second ("higher") tone with the real A2 tone, the > interval will also be an octave, but a "stronger" octave, (under= "STRONGER" > I mean "more distinctive" in analogy with pitch strength - stronger= pitches > have to produce stronger intervals - is it right to say?). > Then the sub-units of the octave in the pitch hight scale have to be > the units of the "octave strength"? But what then to do with this "octave > strength" if the phases manippulation make pitch of the tone becoming > distinctive fifth of the fundamental? > If I am understandable here, I would like to know your opinion. Bregman: I have often thought that the pitch height dimension could separate two C's (for example) by more or by less than a conventional "octave, depending on the spectrum of the tones. Musicians might not like this, but it seems to agree with many phenomenological descriptions like yours. Perhaps we should argue as follows: The octave is a musical concept, not a perceptual one. We assume that an octave is defined by two tones that have the same chroma, but different pitch heights. Typically, when the spectra are similar (whatever that means), a 2:1 ratio of fundamental frequencies gives rise to the difference in pitch height that we associate with an octave. In such cases, (e.g., comparing notes on the same instrument), we don't notice the contribution of the spectrum to pitch height. I think many people have noticed the difficulty with the identification of a given fundamental with a definite pitch height, among them John Pierce at CCRMA. - Al ---------------------------------------------------------------------- Albert S. Bregman, Professor, Dept of Psychology, McGill University 1205 Docteur Penfield Avenue, Montreal, Quebec, Canada H3A 1B1. Phone: +1 514-398-6103 Fax: -4896 Email: bregman(at)hebb.psych.mcgill.ca Lab Web Page: http://www.psych.mcgill.ca/labs/auditory/laboratory.html From: Bob Carlyon Dear Al and Alex, I emailed Alex with a reply to his question, which led to him citing CAr lyon and Shackleton. Al's email made me realise that there is another paper of mine which suggests a pitch-like dimension which may perceptually resemble tone height: JASA vol 102 p1097-1105 (1997): "The effects of two temporal cues on pitch judgements". In it I also cite an article by Roy Patterson in which he varies stimuli continuously from one octave to the next without changing chroma: Contemp. Music Rev 9, p69-81 (1993): What is the octave of a harmonically rich note? cheers bob -------------------------------------------------------------------- Date: Wed, 11 Mar 1998 17:49:40 -0500 From: repp(at)lenny.haskins.yale.edu To: galembo(at)psyc.queensu.ca Subject: Effects of spectral envelope on pitch X-VMS-To: SMTP%"galembo(at)pavlov.psyc.queensu.ca" Hi Sasha: I read with interest Al Bregman's reply to your query. There are probably many ways of demonstrating an influence of spectral envelope on perceived pitch height, but the one I remember best is in a recent paper of mine:=20 Repp, B. H. (1997). Spectral envelope and context effects in the tritone paradox. Perception, 26, 645-665. I show there that Shepard tones, which supposedly have a constant pitch height and vary in chroma only, do vary in perceived pitch height. This seems to be due to the fact that the shape of their discrete spectral envelope varies, even though all envelopes are designed to fit under the=20 same continuous envelope function. Best, Bruno cc: Al Bregman =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Alexander Galembo, Ph. D. NSERC-NATO Science fellow Acoustics lab, Dept. of Psychology, Queen's University Kingston ON K7L3N6=20 Canada Tel. (613) 5456000, ext. 5754 Fax (613) 5452499 E-mail: galembo(at)pavlov.psyc.queensu.ca URL : http://www.geocities.com/CapeCanaveral/Lab/8779/