Subject: Re: [AUDITORY] Localizing smoke detectors - why is it so hard? From: "Richard F. Lyon" <dicklyon@xxxxxxxx> Date: Thu, 27 Jun 2013 12:37:30 -0700 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--001a11c373609f977a04e027e48e Content-Type: text/plain; charset=ISO-8859-1 Ewan, thanks for your paper reference; very relevant. You wrote there, "ITD dominance is shown indirectly in findings that head movements are highly effective for localizing low-frequency targets but not narrow-band high-frequency targets." I agree. But it doesn't address what you could do with wide-band high-frequency targets. If the alarms used 3 kHz, but chopped on and off, with not such a high-Q resonance, they would probably have good enough onsets to help you make use of ITD, yes? I often see people disregarding ITD as a powerful cue above 1 kHz or so; but the basis for that is only that it's not a usable cue for sine waves and other narrow-band signals. Wideband clicks and noises are easy to localize, even if simulated with only ITD. Dick On Wed, Jun 26, 2013 at 1:52 PM, Ewan A. Macpherson < ewan.macpherson@xxxxxxxx> wrote: > Richard F. Lyon wrote, On 6/25/2013 1:43 PM: > > Jennifer, >> >> I believe the answer is primarily in the transducer: to make the beeper >> cheep, they use a resonant transducer, which has a slow buildup at the >> onset and makes the resulting signal not very broadband at all, >> depriving you of all ITD cues. And they make the beeps so brief that >> you don't have much chance to turn your head and vary the ILD cue; >> > > It also turns out that front/back location is much more readily > disambiguated by head turning in stimuli that carry low-frequency ITD than > in those carrying only high-frequency ILD (such as the ~3-kHz, more-or-less > pure tones from smoke detectors). The dynamic ILD cue does not seem to be > able to beat the phantom spectral cue due to the narrow high-frequency peak > in the spectrum. This is true under anechoic conditions, and presumably > would be even worse in reverberation. > > http://asadl.org/poma/**resource/1/pmarcw/v19/i1/**p050131_s1<http://asadl.org/poma/resource/1/pmarcw/v19/i1/p050131_s1> > > EAM > --001a11c373609f977a04e027e48e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div><div><div>Ewan, thanks for your paper reference; very= relevant.<br><br></div>You wrote there, "ITD dominance is shown indir= ectly in findings that head movements are=20 highly effective for localizing low-frequency targets but not=20 narrow-band high-frequency targets."<br><br></div>I agree.=A0 But it d= oesn't address what you could do with wide-band high-frequency targets.= =A0 If the alarms used 3 kHz, but chopped on and off, with not such a high-= Q resonance, they would probably have good enough onsets to help you make u= se of ITD, yes?=A0 <br> <br></div><div>I often see people disregarding ITD as a powerful cue above = 1 kHz or so; but the basis for that is only that it's not a usable cue = for sine waves and other narrow-band signals.=A0 Wideband clicks and noises= are easy to localize, even if simulated with only ITD.<br> </div><div><br></div>Dick<br><br><div><div><br> </div></div></div><div clas= s=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Wed, Jun 26, 2013 a= t 1:52 PM, Ewan A. Macpherson <span dir=3D"ltr"><<a href=3D"mailto:ewan.= macpherson@xxxxxxxx" target=3D"_blank">ewan.macpherson@xxxxxxxx</a>>= </span> wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex">Richard F. Lyon wrote, On 6/25/2013 1:43 PM:= <div class=3D"im"><br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> Jennifer,<br> <br> I believe the answer is primarily in the transducer: =A0to make the beeper<= br> cheep, they use a resonant transducer, which has a slow buildup at the<br> onset and makes the resulting signal not very broadband at all,<br> depriving you of all ITD cues. =A0And they make the beeps so brief that<br> you don't have much chance to turn your head and vary the ILD cue;<br> </blockquote> <br></div> It also turns out that front/back location is much more readily disambiguat= ed by head turning in stimuli that carry low-frequency ITD than in those ca= rrying only high-frequency ILD (such as the ~3-kHz, more-or-less pure tones= from smoke detectors). The dynamic ILD cue does not seem to be able to bea= t the phantom spectral cue due to the narrow high-frequency peak in the spe= ctrum. This is true under anechoic conditions, and presumably would be even= worse in reverberation.<br> <br> <a href=3D"http://asadl.org/poma/resource/1/pmarcw/v19/i1/p050131_s1" targe= t=3D"_blank">http://asadl.org/poma/<u></u>resource/1/pmarcw/v19/i1/<u></u>p= 050131_s1</a><span class=3D"HOEnZb"><font color=3D"#888888"><br> <br> EAM<br> </font></span></blockquote></div><br></div> --001a11c373609f977a04e027e48e--