Re: Loudspeaker with directivity similar to a human talker (Densil Cabrera )

Subject: Re: Loudspeaker with directivity similar to a human talker From: Densil Cabrera <d.cabrera@xxxxxxxx> Date: Thu, 5 Mar 2009 13:27:11 +1100 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY> This is a multi-part message in MIME format. ------_=_NextPart_001_01C99D39.DBD1C290 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Chu & Warnock's long term speech data, together with that for a 4128C head & torso simulator (HATS) could be useful if you do not already know about it - see http://irc.nrc-cnrc.gc.ca/pubs/rr/rr104/rr104.pdf =20 For a simple comparison, we converted these data to directivity index (DI), and compared to our measurements of a head-sized loudspeaker (NTI Talkbox). Up to 630 Hz third oct band, the DI values of humans, HATS and NTI Talkbox are similar (mainly around 2 to 3 dB), with the talkbox becoming increasingly directional at higher frequencies. Roughly speaking, there is about a 3 dB difference in directivity index between 800 Hz and 4000 Hz 1/3-oct bands, and a much larger difference above that. I expect similar results would occur for head-sized loudspeakers with similar diameter drivers (about 800 mm). =20 We did some other tests varying mouth aperture on a HATS, which significantly changed directivty at some frequencies, but did not change measured Speech Transmission Index values in three normal rooms. The effect of directivity (based on theoretical modeling) should be maximum at somewhat less than a critical distance, which in many situations is too close to be of consequence. =20 Cheers Densil =20 ________________________________ From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxx On Behalf Of Jose Almagro Sent: Thursday, 5 March 2009 7:47 AM To: AUDITORY@xxxxxxxx Subject: Re: Loudspeaker with directivity similar to a human talker =20 I think every loudspeaker of the same size a human head has would comply. Norsonic recommends using a Tivoli loudspeaker to measure STIPA with Nor140 analyzer. =20 Best regards. =20 2009/3/4 Tony Miller <antonio.miller@xxxxxxxx> Suggesting a head and torso simulator (HATS) might be overkill on your budget if you are just interested in getting the directivity of an average human mouth.=20 The GRAS mouth simulator has an internal amplifer: http://www.grasinfo.dk/documents/pd_44AB_ver_27_05_05.PDF The B&K mouth simulator requires an external amplifier: http://www.bksv.com/doc/bp0505.pdf Both mouth simulators conform to standards: IEEE 269 and ITU-T P.51. -Tony=20 =20 On Wed, Mar 4, 2009 at 11:10 AM, Pang <sound08@xxxxxxxx> wrote: Dear List I would like to use a loudspeaker with directional properties similar to a human talker to play the speech signals in rooms for speech intelligibility test. I do not know which loudspeakers have directional properties similar to a human talker. Could someone please recommand a loudspeakers for my work? Thanks, Xing Xing =20 =20 ------_=_NextPart_001_01C99D39.DBD1C290 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable <html xmlns:v=3D"urn:schemas-microsoft-com:vml" = xmlns:o=3D"urn:schemas-microsoft-com:office:office" = xmlns:w=3D"urn:schemas-microsoft-com:office:word" = xmlns:st1=3D"urn:schemas-microsoft-com:office:smarttags" = xmlns=3D"http://www.w3.org/TR/REC-html40"> <head> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = charset=3Dus-ascii"> <meta name=3DGenerator content=3D"Microsoft Word 11 (filtered medium)"> <o:SmartTagType namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" = name=3D"City"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"place"/>  <style>  </style>  </head> <body lang=3DEN-US link=3Dblue vlink=3Dblue> <div class=3DSection1> Chu & Warnock’s long term = speech data, together with that for a 4128C head & torso simulator (HATS) = could be useful if you do not already know about it – = see<o:p></o:p> <a href=3D"http://irc.nrc-cnrc.gc.ca/pubs/rr/rr104/rr104.pdf">http://irc.nrc= -cnrc.gc.ca/pubs/rr/rr104/rr104.pdf</a><o:p></o:p> <o:p> </o:p> For a simple comparison, we = converted these data to directivity index (DI), and compared to our measurements = of a head-sized loudspeaker (NTI Talkbox). Up to 630 Hz third oct band, the = DI values of humans, HATS and NTI Talkbox are similar (mainly around 2 to 3 = dB), with the talkbox becoming increasingly directional at higher = frequencies. Roughly speaking, there is about a 3 dB difference in directivity index = between 800 Hz and 4000 Hz 1/3-oct bands, and a much larger difference above = that. I expect similar results would occur for head-sized loudspeakers with = similar diameter drivers (about 800 mm).<o:p></o:p> <o:p> </o:p> We did some other tests varying = mouth aperture on a HATS, which significantly changed directivty at some = frequencies, but did not change measured Speech Transmission Index values in three = normal rooms. The effect of directivity (based on theoretical modeling) should = be maximum at somewhat less than a critical distance, which in many = situations is too close to be of consequence.<o:p></o:p> <o:p> </o:p> Cheers<o:p></o:p> Densil<o:p></o:p> <o:p> </o:p> <div> <div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'> <hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1> </div> From: = AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxx = On Behalf Of Jose Almagro Sent: Thursday, 5 March = 2009 7:47 AM To: = AUDITORY@xxxxxxxx Subject: Re: Loudspeaker = with directivity similar to a human talker<o:p></o:p> </div> <o:p> </o:p> <div>     I think every loudspeaker of the same = size a human head has would comply. Norsonic recommends using a <st1:City = w:st=3D"on"><st1:place w:st=3D"on">Tivoli</st1:place></st1:City> loudspeaker to measure STIPA = with Nor140 analyzer.<o:p></o:p> </div> <div>  <o:p></o:p> </div> <div>     Best regards.    <o:p></o:p> </div> <div> 2009/3/4 Tony Miller <<a = href=3D"mailto:antonio.miller@xxxxxxxx">antonio.miller@xxxxxxxx</a>>= <o:p></o:p> Suggesting a head and torso simulator (HATS) might be overkill = on your budget if you are just interested in getting the directivity of an = average human mouth. The GRAS mouth simulator has an internal amplifer: <a href=3D"http://www.grasinfo.dk/documents/pd_44AB_ver_27_05_05.PDF" target=3D"_blank">http://www.grasinfo.dk/documents/pd_44AB_ver_27_05_05.P= DF</a> The B&K mouth simulator requires an external amplifier: <a href=3D"http://www.bksv.com/doc/bp0505.pdf" = target=3D"_blank">http://www.bksv.com/doc/bp0505.pdf</a> Both mouth simulators conform to standards: IEEE 269 and ITU-T P.51. -Tony <o:p></o:p> <div> <div> <o:p> </o:p> <div> On Wed, Mar 4, 2009 at 11:10 AM, Pang <<a href=3D"mailto:sound08@xxxxxxxx" = target=3D"_blank">sound08@xxxxxxxx</a>> = wrote:<o:p></o:p> Dear List  I would like to use a loudspeaker with directional properties = similar to a human talker to play the speech signals in rooms for speech = intelligibility test.  I do not know which loudspeakers have directional properties similar to a human talker. Could someone please recommand a loudspeakers = for my work?  Thanks,   Xing Xing<o:p></o:p> </div> <o:p> </o:p> </div> </div> </div> <o:p> </o:p> </div> </body> </html> ------_=_NextPart_001_01C99D39.DBD1C290--

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