Subject: Re: HRTF's From: Piotr Majdak <piotr@xxxxxxxx> Date: Mon, 30 Aug 2010 18:57:02 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body text="#000000" bgcolor="#ffffff"> Dear Ranjit,<br> <br> HRTFs are usually considered as a set of <a href="http://en.wikipedia.org/wiki/LTI_system_theory">linear time-invariant systems</a>, the "TF" in HRTF means "<a href="http://en.wikipedia.org/wiki/Transfer_function">transfer function</a>". With that definition, HRTFs change the amplitude and phase of the existing frequencies only and they do not introduce new frequency components. <br> <br> Of course, as everywhere in the acoustics, there could be some nonlinear or modulation effects caused by the pinna (or head and shoulders), however, for sound localization, there is no evidence for such effects until now. All published sound-localization studies I know use HRTFs as they are - without any additional nonlinearities or modulations.<br> <br> Hope that helps,<br> <br> Piotr Majdak<br> <br> <div class="moz-signature">-- <br> Piotr Majdak<br> Psychoacoustics and Experimental Audiology<br> <a href="http://www.kfs.oeaw.ac.at">Acoustics Research Institute</a><br> <a href="http://www.oeaw.ac.at/">Austrian Academy of Sciences</a><br> Wohllebengasse 12-14, 1040 Vienna, Austria<br> Tel.: +43 1 51581-2511<br> Fax: +43 1 51581-2530</div> <br> <br> Ranjit Randhawa wrote: <blockquote cite="mid:20100830155016.158743FC1@xxxxxxxx" type="cite"> Dear List, <br> Could some one help to clarify as to whether HRTF's would introduce high frequency components to a low frequency sinusoid (let it be 300 hz) in determining its elevation. Further, would this signal sound any different if it was in front at zero degree elevation and azimuth versus at some other location? I guess I am also trying to find out how the pinna would interact with the signal to create any high frequency components and therefore will our ability to determine elevation of low frequency signals be degraded considerably? Sorry for so many questions, I have not been able to find out any references (net accessible) to such day dreaming. <br> Thanks for your help in advance, sincerely, <br> Randhawa <br> </blockquote> <br> </body> </html>