Re: High-frequency hearing in humans (Antonio Miller )


Subject: Re: High-frequency hearing in humans
From:    Antonio Miller  <antonio.miller@xxxxxxxx>
Date:    Wed, 26 Jan 2011 17:28:26 -0500
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

We'll see if someone tears this argument apart, but you got me thinking... The propagation of sound in the atmosphere is pretty complicated [1], but some simplified calculations might be relevant to this question. Attenuation of sound in Air at 100m [2]: f<2kHz, less than 2dB f=4kHz, 3dB f=8kHz, 10dB f=16kHz, 36dB A (very rough) calculation for a detection radius of a sound that is 20dB above hearing threshold: 56m for 16kHz 200m for 8kHz 667m for 4kHz Meaning, you would have to be almost four times closer to the 16kHz sound to detect it as the 8kHz sound. Assuming the 8 and 16kHz sound are equally biologically relevant, I would tend to weight the information content of the 16kHz sound much higher due to it's relative spatial scarcity. Does that make sense to anyone? Maybe the ability to hear higher frequency sounds helps lend a competitive advantage because they only exist within short distances of the sound source? -Tony [1] http://en.wikibooks.org/wiki/Engineering_Acoustics/Outdoor_Sound_Propagation#endnote_HandbookofAcoustics1998 [2] Air @xxxxxxxx 1 atm, 20deg C, 50% relative humidity. On Tue, Jan 25, 2011 at 4:27 AM, Piotr Majdak <piotr@xxxxxxxx> wrote: > Dear list, > > I'm looking for the reasons for the good high-frequency* hearing  in humans. > > The reasons I have until now are actually the obvious ones: > * Pinna localization cues > * Interaural level cues (ILD, they actually start to work from around 2 kHz) > > What do you think: if there were no need for the ILD and pinna cues, would > there be any other reasons? > > Thanks, > > Piotr > *) say, above 8 kHz > > -- > Piotr Majdak > Psychoacoustics and Experimental Audiology > Acoustics Research Institute <http://www.kfs.oeaw.ac.at> > Austrian Academy of Sciences <http://www.oeaw.ac.at/> > Wohllebengasse 12-14, 1040 Vienna, Austria > Tel.: +43 1 51581-2511 > Fax: +43 1 51581-2530 >


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