Subject: Interesting case related to pitch perception From: Arturo Camacho <acamacho@xxxxxxxx> Date: Fri, 27 Jul 2007 17:13:07 -0400 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>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 -- __________________________________________________ Arturo Camacho PhD Candidate Computer and Information Science and Engineering University of Florida E-mail: acamacho@xxxxxxxx Web page: www.cise.ufl.edu/~acamacho __________________________________________________