Dr. Hendrik Husstedt, Lübeck
Video 14 
2018
“Can percentile sound pressure levels be used to determine the signal-to-noise ratio?”
Modern hearing aids provide features such as noise reduction or directional microphones to increase the signal-to-noise ratio, and make signals easier to understand. One possibility to analyse the effect of these features on the SNR is computing percentile sound pressure levels according to IEC 60118-15. However, the question arises as to what extent a clear correlation exists between the percentile levels and the SNR.
Therefore, in this presentation, I shall show how the percentile levels correspond to the SNR. To this end, the difference between the 99th and 30th percentiles is analysed for a superposition of the International Speech Test Signal (ISTS) with the IFnoise. These results demonstrate that a unique relation between the SNR and the percentile difference can be found for some situations. Nevertheless, a comparison with the results from the phase inversion method by Hagerman and Olofsson shows some differences for certain situations. Finally, based on these findings, I shall discuss if percentile levels are reasonable parameters for determining the signal-to-noise ratio.