Subject: Re: Question on defining S/N ratio in speech-in-noise testing From: DeLiang Wang <dwang@xxxxxxxx> Date: Thu, 13 Aug 2009 15:43:30 -0400 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>It's a tricky issue. If one doesn't exclude gaps (silences) between words/sentences, the calculated SNR will likely underestimate the actual SNR. On the other hand, completely excluding the noises in such gaps will likely overestimate the actual SNR since these noises do have an adverse impact on target speech due to forward masking effects. In a recent intelligibility study on normal-hearing and hearing-impaired listeners, we count the noise within the 100-ms period before a speech onset in our SNR calculations (see Sect. III.A.1, JASA 125, pp. 2336-2347, 2009). DeLiang Leonid Litvak wrote: > 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 -- ------------------------------------------------------------ Prof. DeLiang Wang Department of Computer Science and Engineering The Ohio State University 2015 Neil Ave. Columbus, OH 43210-1277, U.S.A. Phone: 614-292-6827 (OFFICE); 614-292-7402 (LAB) Fax: 614-292-2911 URL: http://www.cse.ohio-state.edu/~dwang