Question on defining S/N ratio in speech-in-noise testing

[Leonid Litvak <lmlitvak@xxxxxxxxx>]

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