Re: Question on defining S/N ratio in speech-in-noise testing (Densil Cabrera )

Subject: Re: Question on defining S/N ratio in speech-in-noise testing From: Densil Cabrera <d.cabrera@xxxxxxxx> Date: Thu, 13 Aug 2009 09:13:07 +1000 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY> This is a multi-part message in MIME format. ------_=_NextPart_001_01CA1BA2.6F04C757 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Hi Leo, With regard to temporal analysis, an alternative to the equivalent sound pressure level (=3Dlong term rms) is the 'active speech level', as = defined by ITU-T P.56. This disregards the 'silences' in the speech, and also can quantify the ratio of speech to 'silence'. This seems to be a quite sensible approach to quantifying speech level, but I am not sure if it is used in research much beyond the telecommunications field. dc =20 -----Original Message----- From: AUDITORY - Research in Auditory Perception on behalf of Leonid Litvak Sent: Thu 8/13/2009 5:57 AM To: AUDITORY@xxxxxxxx Subject: [AUDITORY] Question on defining S/N ratio in speech-in-noise testing Hi All, I have a question regarding definition of signal-to-noise ratio as it applies to speech-in-noise testing, with speech material being sentences. On a simple level, SNR is just level of the signal divided by the level of the noise. The signal is typically speech, so its level fluctuates over time. Do people typically use the average signal level computed over the whole sentence, average signal level computed in 100 ms windows, medium signal level, maximum signal level, etc.? The same question could go for the noise token as well. I would very much appreciate references to papers that discuss these issues. Finally, we are interested to apply these tests to cochlear implant recipients that have a well-characterized pre-emphasis curve as part of their processor. Should the pre-emphasis curve be taken into account when computing S/N ratios? This is not an issue for spectrally-matched noises, but may be an issue for non-matched noises. Thank you very much! Leo ------_=_NextPart_001_01CA1BA2.6F04C757 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=3D"http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv=3DContent-Type content=3D"text/html; = charset=3Dus-ascii"> <meta name=3DGenerator content=3D"Microsoft Word 11 (filtered medium)"> <title>RE: [AUDITORY] Question on defining S/N ratio in speech-in-noise = testing</title> <style>  </style>  </head> <body lang=3DEN-US link=3Dblue vlink=3Dpurple> <div class=3DSection1> Hi = Leo,<o:p></o:p> With regard to temporal analysis, = an alternative to the equivalent sound pressure level (=3Dlong term rms) is = the ‘active speech level’, as defined by ITU-T P.56. This disregards the = ‘silences’ in the speech, and also can quantify the ratio of speech to = ‘silence’. This seems to be a quite sensible approach to quantifying speech level, = but I am not sure if it is used in research much beyond the telecommunications = field.<o:p></o:p> dc<o:p></o:p> <o:p> </o:p> -----Original Message----- From: AUDITORY - Research in Auditory Perception on behalf of Leonid = Litvak Sent: Thu 8/13/2009 5:57 AM To: AUDITORY@xxxxxxxx Subject: [AUDITORY] Question on defining S/N ratio in speech-in-noise = testing Hi All, I have a question regarding definition of signal-to-noise ratio as = it applies to speech-in-noise testing, with speech material being = sentences. On a simple level, SNR is just level of the signal divided by the level of = the noise. The signal is typically speech, so its level fluctuates over time. Do = people typically use the average signal level computed over the whole = sentence, average signal level computed in 100 ms windows, medium signal = level, maximum signal level, etc.? The same question could go for the noise token as well. I would very much appreciate references to papers that discuss these = issues. Finally, we are interested to apply these tests to cochlear implant recipients that have a well-characterized pre-emphasis curve as part = of their processor. Should the pre-emphasis curve be taken into account = when computing S/N ratios? This is not an issue for spectrally-matched = noises, but may be an issue for non-matched noises. Thank you very much! Leo<o:p></o:p> </div> </body> </html> ------_=_NextPart_001_01CA1BA2.6F04C757--

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Electrical Engineering Dept., Columbia University