Subject: Re: Interesting case related to pitch perception From: Stefan Strahl <stefan.strahl@xxxxxxxx> Date: Sat, 28 Jul 2007 00:27:49 +0100 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Hi Arturo :) I don't know if this helps but looking at the spectrogram of it http://www.student.uni-oldenburg.de/stefan.strahl/G6.jpg it shows that the 500Hz harmonic complex is only present while the on- and the offset of the tone. I don't know about your experiment design, but if I "remove" them by windowing the waveform so that the first 50ms and the last 100ms are silenced I still have the same pitch percept - perhaps this would be a solution? :) stefan -- Dipl.-Math./Inf. MSc Stefan Strahl University of Oldenburg Department of Physics Signal Processing Group 26111 Oldenburg, Germany Room W2 2-247b Phone +49 441 798 3249 EMail stefan.strahl@xxxxxxxx Arturo Camacho wrote: > Dear members of the list, > > I am analyzing the spectrum of musical instruments in a pitch-related > study and found something that puzzles me: the spectrum of an oboe playing > the note G6 (approximately 1500 Hz pitch) contains peaks not only at > multiples of 1500 Hz but also at each multiple of 500 Hz. This was > observed in a sample taken from the University of Iowa Musical Instruments > Database (http://theremin.music.uiowa.edu/MIS.html), specifically, the 8th > note in the file "oboe.pp.C6Ab6.aiff". I do not know much about wind > instruments, but my guess is that the position used to play G6 is probably > the same used to play C5 and the only difference is the pressure in the > mouth. This could leave the harmonics of C5 alive and that is why there is > energy at multiples of 500 Hz. If someone know the reasons of this effect > please let me see the light, because it would be nice to offer an > explanation of this in my study. > > As an aside, this is an interesting example of a case in which the pitch > is different from the fundamental. From the log-magnitude of the spectrum > it is very clear that the signal consists of multiples of 500 Hz (although > with boosted 3rd, 6th, 9th, etc. harmonics), and therefore, the > fundamental frequency, if any, should be considered as 500 Hz and not 1500 > Hz. > > Arturo
