Subject: Re: Cochlea Amplifier models : a new list From: Matt Flax <flatmax@xxxxxxxx> Date: Fri, 19 Oct 2007 11:00:36 +1000 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Hi Again, Your statement "OHC's actively feed energy into the travelling wave" is this the point you are trying to make ??? To re-address two of the papers which I consider significant ... Robles [1] Figure 14 - Phase increases away from stapes ... agreed. I have no problem with Bekesey's PASSIVE travelling wave... it is a good thing he won a Nobel peace prize for it ... in my opinion. To us he is like Newton. Would you agree ? A g-dfather of Auditory physics. Ren [2] Figure 2 - BM motion and emissions have roughly the same phase and same delay. The activity in the cochlea - with respect to DPOAEs and other OAEs - are as fast (or slightly faster depending on tonotopic location) as the travelling wave. Indeed it is now emerging that apical emissions are quite likely FASTER ! ... further ... I believe that Ren questions whether energy is 'fed into' the travelling wave... particularly in his later paper these points become more clear [3]. By the way - on a lighter note - I would like to re-iterate someone else's musings ... where is the Ren.T. ? Dan, is the land lord unhappy or can we give more time for the Ren.T. ? Normally his delay is as fast as travelling there... Matt [1] http://scholar.google.com.au/scholar?hl=en&lr=&cluster=17820753968464962563 Mechanics of the Mammalian Cochlea L Robles, MA Ruggero - Physiological Reviews, 2001 - Am Physiological Soc [2] http://scholar.google.com.au/scholar?hl=en&lr=&cluster=16221017648687364199 Reverse propagation of sound in the gerbil cochlea T Ren - Nature Neuroscience, 2004 - nature.com [3] http://scholar.google.com.au/scholar?hl=en&lr=&cluster=12841431453571646773 Group Delay of Acoustic Emissions in the Ear T Ren, W He, M Scott, AL Nuttall - Journal of Neurophysiology, 2006 - Am Physiological Soc On Thu, Oct 18, 2007 at 07:55:54PM +0000, reinifrosch@xxxxxxxx wrote: > Hello Matt Flax and List, > > Answers to your posting of Oct. 18: > > 1) Fig. 14 of Robles and Ruggero (2001) shows data of > Russell and Nilsen (1997), "The location of the cochlear > amplifier: spatial representation of a single tone on the > guinea pig basilar membrane", Proc Natl Acad Sci USA 94: > 2660-2664; (this PNAS paper can be downloaded freely). > > Yes, animal was alive and sedated. BM displacements were > measured using "the self-mixing effect of a laser diode". > Light directly reflected from the BM. Fig. 1 of that PNAS > paper is similar to Fig. 14 of Robles and Ruggero (2001), > so you can look at the broad passive response peaks at > x_a = 15.85 mm and at the narrower active peaks at > x_a = 14.47 mm yourself. The phase measurements are > shown in Fig. 2B of the PNAS paper; the phase decreases > if x_b increases (where x_b = 19mm - x_a); this shows > that the wave travels from base to apex. > > 2) Fig. 1C of Ren et al. (2003), "Measurement of Basilar- > Membrane Vibration ...": > The mentioned book "Biophysics of the Cochlea" (2003) is > the proceedings of the international "Mechanics of Hearing" > symposium at Titisee (Germany), July 27 to August 1, 2002. > That book is certainly in many libraries. The mentioned > Fig. 1C of Ren et al. demonstrates the travelling wave in > the active-peak x_b-region especially clearly --- but the > fact that this travelling wave exists is proven already by the > PNAS paper mentioned under point 1 above (and by many > other papers with phase measurements of course). I do not > understand the part of your message from "Normally Ren's > papers ..." to "... common knowledge". In my opinion the > travelling wave is entirely passive from the stapes to the > small-x_b limit of the active-peak region. Only for x_b-values > between that limit and the top of the active peak do the > OHC's actively feed energy into the travelling wave, as > indicated, e.g., by the negative real part of the BM > impedance in Fig. 3 of de Boer and Nutall (1999), discussed > under my point 4. Would you please give me references for > "Ren's other papers"? > > 3) Fig. 1b of Mammano and Ashmore (1993), "Reverse > transduction ...": > RL (Hensen-cell resonator) has a resonance frequency > deeper, by a factor of about (1 / 2.3), than the resonance > frequency of the BM-resonator at the same place: > Here we appear to agree then. > > 4) Fig. 3 of de Boer and Nuttall (1999), "The inverse > problem solved ...": > Section VII of that paper is entitled "Conclusions and > reasons for caution", and the first mentioned reason for > caution is: "Long-wave behavior is assumed at and near > (x=0)". Indeed, my calculations have yielded that for the > considered case (guinea pigs, 16.8 kHz) the long-wave > condition (k*H << 1; see, e.g., Section 4 of de Boer's > chapter in the book "The Cochlea", Springer, 1996) is > strongly violated. Possibly there are reasons to hope that > the results of de Boer and Nuttall are approximately correct > in spite of that violation. > > Reinhart Frosch. > > Reinhart Frosch, > Dr. phil. nat., > r. PSI and ETH Zurich, > Sommerhaldenstr. 5B, > CH-5200 Brugg. > Phone: 0041 56 441 77 72. > Mobile: 0041 79 754 30 32. > E-mail: reinifrosch@xxxxxxxx . > > ----Ursprüngliche Nachricht---- > Von: flatmax@xxxxxxxx > Datum: 18.10.2007 05:53 > An: <reinifrosch@xxxxxxxx>, <AUDITORY@xxxxxxxx> > Betreff: Re: Cochlea Amplifier models : a new list > > Dear Reinhart and list, > > In a manner similar to Martin, Richard and others, I will go > through the examples you have pointed out. > > I also am unsure of what these points are leading to. > I am very interested to hear your conclusion. > > Results pointed out by Reinhart: > 1) I can confirm that you are pointing out two peaks. I am > not sure about the particulars of the experiment - how > visualisation was accomplished. I assume that the animal > was alive and sedated. The locations pointed out using your > assumptions are that : > a] Active peak in an apical location to the passive peak > b] Passive peak in basal location to active peak. > > 2) I can not get this reference currently. Normally Ren's > papers are about delay. Ren's other papers have continuity > in that they point out delays are normally as fast or faster > then the travelling wave delay for OAEs. For this reason, > Ren points out that active processes are too quick to > maintain the active travelling wave hypothesis. We > have known this point since the eighties and it should now > be common knowledge. > > 3) I can confirm that in the dead animal, the RL responds in > a resonant manner below the BM frequency at the same > point of reference. The interpretation is that the RL is tuned > more then an octave below the BM at the same tonotopic > location. > > 4) I can see the projected negative damping which is > calculated using inverse techniques. I trust your > interpretation of this image which is "the distance between > active and passive peaks is 1.4 mm and so corresponds to > half an octave." I would like to point out that inverse > solutions are numerical interpretations. Guiding numerical > points of view if you will. You further reference high level > perception of pitch "a perceived-pitch difference much > smaller that half an octave" > > I trust that I have not mislead the readers and am repeating > your train of thought as confirmation for the list. > > Matt > > On Wed, Oct 17, 2007 at 03:11:20PM +0000, reinifrosch@xxxxxxxx > wrote: > > Hello Matt and List, > > > > Because of a nice one-week stay in Montreal (CAA-2007 > conference) > > this reaction to your posting of Oct. 9 is very late. After > having > > read the many answers to your cochlear-amplifier question, > however, I > > would like to suggest to some of the contributors to look at > the > > following figures in journals and books. Some of my remarks on > these > > four figures are very tentative of course. > > > > 1) L. Robles and M. A. Ruggero (2001), "Mechanics of the > Mammalian > > Cochlea", Physiological Review 81, 1306-1352; the upper part of > Fig. > > 14 shows data of Russell and Nilsen on guinea-pig BM > displacement > > versus cochlear longitudinal position x_a in response to 15-kHz > > sinusoidal tones; x_a, the distance from the apex, ranges from > 13.5 > > to 17 mm; BM length is about 19 mm; so x_b, the distance from > the > > base, ranges from about 2 to 5.5 mm. At sound pressure levels > (SPL) > > of 15, 20, 25, ... , 60, 70 dB there is an active peak at about > x_a = > > 14.47 mm. At SPL = 55, 60, ... , 90, 100 dB there is a passive > peak > > at about x_a = 15.86 mm. At SPL < 55 dB no data are shown in > the > > passive-peak x_a-region. > > > > 2) T. Y. Ren et al. (2003), "Measurement of Basilar-Membrane > > Vibration Using a Scanning Laser Interferometer", in the book > > "Biophysics of the Cochlea", A. W. Gummer, ed., World Scientific, > New > > Jersey, etc., 211-219; Fig. 1C shows gerbil BM velocity versus > > distance x_b from the base in response to a sinusoidal tone of 16 > kHz > > and 40 dB (SPL). There are four curves, measured at times T/8, > T/4, > > 3T/8, and T/2, where T = (1second) / 16000 is the wave period; > x_b > > ranges from 2.1 to 3 mm; a hint of the passive peak is visible at > x_b > > = 2.1 mm; the active peak is at x_b = 2.6 mm and has a full width > at > > half maximum of 0.25 mm. The four curves in Fig. 1C show that > there > > is a wave travelling on the BM, in the +x_b-direction (i.e., > from > > base to apex), across the active-peak x_b-region. At the active- > peak > > centre (x_b = 2.6 mm) the phase velocity of the travelling wave > (e. > > g., the speed of a wave zero) is 3.2 m/s. > > > > 3) F. Mammano and J. F. Ashmore (1993), "Reverse transduction > > measured in the isolated cochlea by laser Michelson > interferometry", > > Nature, 838-841. Fig. 1b shows the motion of aluminium-coated > glass > > beads placed on the BM and on the Hensen-cell region of the RL > > (reticular lamina) of post-mortem guinea-pigs in response to 4- > > millisecond-long rectangular electric-current pulses. Of > interest > > here are the damped oscillations at the beginning and at the end > of > > these current pulses, since they allow the determination of the > > resonance frequency (i.e., the frequency that the oscillations > would > > have without damping) of the resonators to which the observed > spots > > belong. At the observed place, the resonance frequency of the > BM- > > resonator (spring = BM fibres; mass = organ of Corti) was found > to be > > 2.3 kHz, and that of the "Hensen-cell" resonator (spring = outer > hair > > cells and maybe elastic parts of the the Deiters cells; mass = > Hensen > > cells and other nearby structures) was 1.0 kHz. I suspect that > this > > Hensen-cell resonator (oscillating so that the angle formed by > the RL > > and the BM varies) is the "second degree of freedom", rather than > the > > tectorial membrane (TM) suspended on two springs mentioned, e.g., > in > > Section 7.1 of E. de Boer's chapter in the book "The Cochlea" > > (Springer, 1996). > > > > 4) E. de Boer and A. L. Nuttall (1999), "The 'inverse problem' > > solved for a three-dimensional model of the cochlea. III. > Brushing-up > > the solution method.", JASA 105, 3410-3420; the lower panel of > Fig. 3 > > shows the guinea-pig BM impedance (across-BM pressure > difference > > divided by BM velocity) versus location x_b (expressed in percent > of > > 6 mm) for a sine-tone of 16.8 kHz and 20 dB (SPL). In the region > from > > 67 to 84 percent, i.e., from x_b = 4.0 to x_b = 5.0 mm, the real > part > > of the impedance is negative; that implies "negative damping"; i. > e., > > it implies that in this x_b-region the outer hair cells (OHC's) > feed > > energy into the travelling wave. At locations x_b < 4.0 mm, the > > resonance-peak frequency region of the Hensen-cell resonator > (see > > point 3 above) is above 16.8 kHz so that these resonators are > not > > excited significantly by the wave. At x_b = 4.0 mm, the low- > frequency > > limit of the just mentioned resonance-peak frequency region is > at > > 16.8 kHz, so that from that location onwards the resonator is > > excited, and the motor proteins in the OHC walls are caused to > > operate, maybe both via modulation of the electric current into > the > > OHC hairs and via direct mechanical stimulation of the OHC walls. > At > > x_b > 5.0 mm, the Hensen-cell-resonator's resonance-peak region > is > > below 16.8 kHz, so that the OHC's do not feed energy into the > > travelling wave. The highest point of the active peak, shown in > the > > upper panel of Fig. 3, (i.e., the characteristic place of the > 16.8- > > kHz-20-dB wave) is at that last-mentioned position of x_b = 5.0 > mm. > > Extrapolation of the short-dashed curve in the lower panel > yields > > that the imaginary part of the BM-impedance vanishes at about x_b > = > > 130 percent = 7.8 mm; thus the resonance frequency of the BM- > > oscillator (see point 3 above) at x_b = 7.8 mm is 16.8 kHz. The > 16.8- > > kHz travelling wave does not reach that point. According to the > upper > > panel, the passive peak (same wave, dead OHC's) is at about x_b = > 60 > > percent = 3.6 mm. Thus the distance between active and passive > peaks > > is 1.4 mm and so corresponds to half an octave. In the case of > two > > similar, but lower-frequency waves in human ears, e.g. 1kHz,20dB > and > > 1kHz,100dB, there is a similar x_b-difference but (since mostly > time- > > information is used) a perceived-pitch difference much smaller > than > > half an octave; see, e.g., Chapter 6 of "An Introduction to the > > Psychology of hearing" by B. C. J. Moore, Academic Press, > Amsterdam > > etc., 5th ed., 2003. > > > > Reinhart Frosch. > > > > Reinhart Frosch, > > Dr. phil. nat., > > r. PSI and ETH Zurich, > > Sommerhaldenstr. 5B, > > CH-5200 Brugg. > > Phone: 0041 56 441 77 72. > > Mobile: 0041 79 754 30 32. > > E-mail: reinifrosch@xxxxxxxx . > > > > ----Ursprüngliche Nachricht---- > > Von: flatmax@xxxxxxxx > > Datum: 09.10.2007 11:35 > > An: <AUDITORY@xxxxxxxx> > > Betreff: Cochlea Amplifier models : a new list > > > > Hello, > > > > After our discussion last week, I have made a new list of > possible > > physiological Cochlea Amplifiers (some of these are weakly > > physiologically based). 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