Subject: Re: [AUDITORY] Localizing smoke detectors - why is it so hard? From: Pierre Divenyi <pdivenyi@xxxxxxxx> Date: Thu, 27 Jun 2013 21:41:59 -0700 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>> This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3455214123_8657781 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit You are right, Dick! A series of recent papers on "transposed AM sounds" by Les Bernstein and Tino Trahiotis show very clearly that periodically interrupted high-frequency carriers are localizable based on ITD. -Pierre On 6/27/13 12:37 PM, "Richard F. Lyon" <dicklyon@xxxxxxxx> wrote: 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 --B_3455214123_8657781 Content-type: text/html; charset="US-ASCII" Content-transfer-encoding: quoted-printable <html><head></head><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: s= pace; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size:= 16px; font-family: Calibri, sans-serif; "><div>You are right, Dick! A serie= s of recent papers on "transposed AM sounds" by Les Bernstein and Tino Trahi= otis show very clearly that periodically interrupted high-frequency carriers= are localizable based on ITD.</div><div>-Pierre</div><div><br></div><span i= d=3D"OLK_SRC_BODY_SECTION"><div><div>On 6/27/13 12:37 PM, "Richard F. Lyon" &l= t;<a href=3D"mailto:dicklyon@xxxxxxxx">dicklyon@xxxxxxxx</a>> wrote:</div></d= iv><div><br></div><div dir=3D"ltr"><div><div><div>Ewan, thanks for your paper = reference; very relevant.<br><br></div>You wrote there, "ITD dominance is sh= own indirectly in findings that head movements are highly effective for localizing low-frequency targets but not narrow-band high-frequency targets."<br><br></div>I agree. But it doe= sn'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 res= onance, they would probably have good enough onsets to help you make use of = ITD, yes? <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. Wideband c= licks 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 class=3D= "gmail_extra"><br><br><div class=3D"gmail_quote">On Wed, Jun 26, 2013 at 1:52 = PM, Ewan A. Macpherson <span dir=3D"ltr"><<a href=3D"mailto:ewan.macpherson@xxxxxxxx= ca.uwo.ca" target=3D"_blank">ewan.macpherson@xxxxxxxx</a>></span> wrote:<= br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px = #ccc solid;padding-left:1ex">Richard F. Lyon wrote, On 6/25/2013 1:43 PM:<di= v class=3D"im"><br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bo= rder-left:1px #ccc solid;padding-left:1ex"> Jennifer,<br><br> I believe the answer is primarily in the transducer: to make the beep= er<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. And they make the beeps so brief that<= br> you don't have much chance to turn your head and vary the ILD cue;<br></blo= ckquote><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 car= rying only high-frequency ILD (such as the ~3-kHz, more-or-less pure tones f= rom smoke detectors). The dynamic ILD cue does not seem to be able to beat t= he phantom spectral cue due to the narrow high-frequency peak in the spectru= m. This is true under anechoic conditions, and presumably would be even wors= e in reverberation.<br><br><a href=3D"http://asadl.org/poma/resource/1/pmarcw/= v19/i1/p050131_s1" target=3D"_blank">http://asadl.org/poma/<u></u>resource/1/p= marcw/v19/i1/<u></u>p050131_s1</a><span class=3D"HOEnZb"><font color=3D"#888888"= ><br><br> EAM<br></font></span></blockquote></div><br></div></span></body></html> --B_3455214123_8657781--