Re: High-frequency hearing in humans (David John SMith )


Subject: Re: High-frequency hearing in humans
From:    David John SMith  <smithd@xxxxxxxx>
Date:    Wed, 26 Jan 2011 18:28:20 -0500
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

----------MB_8CD8BC7D9ED6204_11C8_2E0E_web-mmc-d01.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" =20 So, the distance to familiar broad band sound sources could be judged very= quickly - eg. while they are moving. A chart of the 1db reduction to distance should give an approximate minimu= m effective range for these observations. Well played Tony!??=20 Dave =20 -----Original Message----- From: Antonio Miller &lt;antonio.miller@xxxxxxxx&gt; To: AUDITORY@xxxxxxxx Sent: Wed, Jan 26, 2011 4:31 pm Subject: Re: [AUDITORY] High-frequency hearing in humans =20 =20 =20 We'll see if someone tears this argument apart, but you got me thinking...= =20 =20 The propagation of sound in the atmosphere is pretty complicated [1],=20 but some simplified calculations might be relevant to this question.=20 =20 Attenuation of sound in Air at 100m [2]:=20 f&lt;2kHz, less than 2dB=20 f=3D4kHz, 3dB=20 f=3D8kHz, 10dB=20 f=3D16kHz, 36dB=20 =20 A (very rough) calculation for a detection radius of a sound that is=20 20dB above hearing threshold:=20 =20 56m for 16kHz=20 200m for 8kHz=20 667m for 4kHz=20 =20 Meaning, you would have to be almost four times closer to the 16kHz=20 sound to detect it as the 8kHz sound. Assuming the 8 and 16kHz sound=20 are equally biologically relevant, I would tend to weight the=20 information content of the 16kHz sound much higher due to it's=20 relative spatial scarcity. Does that make sense to anyone? Maybe the=20 ability to hear higher frequency sounds helps lend a competitive=20 advantage because they only exist within short distances of the sound=20 source?=20 =20 -Tony=20 =20 [1] http://en.wikibooks.org/wiki/Engineering_Acoustics/Outdoor_Sound_Propa= gation#endnote_HandbookofAcoustics1998=20 [2] Air @xxxxxxxx 1 atm, 20deg C, 50% relative humidity.=20 =20 On Tue, Jan 25, 2011 at 4:27 AM, Piotr Majdak &lt;piotr@xxxxxxxx&gt; wro= te:=20 &gt; Dear list,=20 &gt;=20 &gt; I'm looking for the reasons for the good high-frequency* hearing ?in= humans.=20 &gt;=20 &gt; The reasons I have until now are actually the obvious ones:=20 &gt; * Pinna localization cues=20 &gt; * Interaural level cues (ILD, they actually start to work from around= 2 kHz)=20 &gt;=20 &gt; What do you think: if there were no need for the ILD and pinna cues,= would=20 &gt; there be any other reasons?=20 &gt;=20 &gt; Thanks,=20 &gt;=20 &gt; Piotr=20 &gt; *) say, above 8 kHz=20 &gt;=20 &gt; --=20 &gt; Piotr Majdak=20 &gt; Psychoacoustics and Experimental Audiology=20 &gt; Acoustics Research Institute &lt;http://www.kfs.oeaw.ac.at&gt;=20 &gt; Austrian Academy of Sciences &lt;http://www.oeaw.ac.at/&gt;=20 &gt; Wohllebengasse 12-14, 1040 Vienna, Austria=20 &gt; Tel.: +43 1 51581-2511=20 &gt; Fax: +43 1 51581-2530=20 &gt;=20 =20 =20 ----------MB_8CD8BC7D9ED6204_11C8_2E0E_web-mmc-d01.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii" <div style=3D"font-family: arial; color: black; font-size: 10pt;"> <br> So, the distance to familiar broad band sound sources could be judged very= quickly - eg. while they are moving.<br> A chart of the 1db reduction to distance should give an approximate minimu= m effective range for these observations.<br> Well played Tony!&nbsp;&nbsp; <br> Dave<br> <br> </div> <div> <br> </div> <div><br> </div> -----Original Message-----<br> From: Antonio Miller &lt;antonio.miller@xxxxxxxx&gt;<br> To: AUDITORY@xxxxxxxx<br> Sent: Wed, Jan 26, 2011 4:31 pm<br> Subject: Re: [AUDITORY] High-frequency hearing in humans<br> <br> <br> <div id=3D"AOLMsgPart_0_d372cfee-fe05-4f9e-a1b8-f977b3bcfbd1" style=3D"mar= gin: 0px; font-family: Tahoma,Verdana,Arial,Sans-Serif; font-size: 12px;= color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);"> <br> <br> <pre style=3D"font-size: 9pt;"><tt>We'll see if someone tears this argumen= t apart, but you got me thinking... <br> <br> The propagation of sound in the atmosphere is pretty complicated [1], <br> but some simplified calculations might be relevant to this question. <br> <br> Attenuation of sound in Air at 100m [2]: <br> f&lt;2kHz, less than 2dB <br> f=3D4kHz, 3dB <br> f=3D8kHz, 10dB <br> f=3D16kHz, 36dB <br> <br> A (very rough) calculation for a detection radius of a sound that is <br> 20dB above hearing threshold: <br> <br> 56m for 16kHz <br> 200m for 8kHz <br> 667m for 4kHz <br> <br> Meaning, you would have to be almost four times closer to the 16kHz <br> sound to detect it as the 8kHz sound. Assuming the 8 and 16kHz sound <br> are equally biologically relevant, I would tend to weight the <br> information content of the 16kHz sound much higher due to it's <br> relative spatial scarcity. Does that make sense to anyone? Maybe the <br= > ability to hear higher frequency sounds helps lend a competitive <br> advantage because they only exist within short distances of the sound <br> source? <br> <br> -Tony <br> <br> [1] <a>http://en.wikibooks.org/wiki/Engineering_Acoustics/Outdoor_Sound_Pr= opagation#endnote_HandbookofAcoustics1998</a> <br> [2] Air @xxxxxxxx 1 atm, 20deg C, 50% relative humidity. <br> <br> On Tue, Jan 25, 2011 at 4:27 AM, Piotr Majdak &lt;<a>piotr@xxxxxxxx</a>&= gt; wrote: <br> &gt; Dear list, <br> &gt; <br> &gt; I'm looking for the reasons for the good high-frequency* hearing &nbs= p;in humans. <br> &gt; <br> &gt; The reasons I have until now are actually the obvious ones: <br> &gt; * Pinna localization cues <br> &gt; * Interaural level cues (ILD, they actually start to work from around= 2 kHz) <br> &gt; <br> &gt; What do you think: if there were no need for the ILD and pinna cues,= would <br> &gt; there be any other reasons? <br> &gt; <br> &gt; Thanks, <br> &gt; <br> &gt; Piotr <br> &gt; *) say, above 8 kHz <br> &gt; <br> &gt; -- <br> &gt; Piotr Majdak <br> &gt; Psychoacoustics and Experimental Audiology <br> &gt; Acoustics Research Institute &lt;<a>http://www.kfs.oeaw.ac.at</a>&gt;= <br> &gt; Austrian Academy of Sciences &lt;<a>http://www.oeaw.ac.at/</a>&gt; <b= r> &gt; Wohllebengasse 12-14, 1040 Vienna, Austria <br> &gt; Tel.: +43 1 51581-2511 <br> &gt; Fax: +43 1 51581-2530 <br> &gt; <br> </tt></pre> <br> </div> <br> ----------MB_8CD8BC7D9ED6204_11C8_2E0E_web-mmc-d01.sysops.aol.com--


This message came from the mail archive
/home/empire6/dpwe/public_html/postings/2011/
maintained by:
DAn Ellis <dpwe@ee.columbia.edu>
Electrical Engineering Dept., Columbia University