Relationship between speech recognition in noise and sparseness

Abstract

Objective: Established methods for predicting speech recognition in noise require knowledge of clean speech signals, placing limitations on their application. The study evaluates an alternative approach based on characteristics of noisy speech, specifically its sparseness as represented by the statistic kurtosis. Design: Experiments 1 and 2 involved acoustic analysis of vowel-consonant-vowel (VCV) syllables in babble noise, comparing kurtosis, glimpsing areas, and extended speech intelligibility index (ESII) of noisy speech signals with one another and with pre-existing speech recognition scores. Experiment 3 manipulated kurtosis of VCV syllables and investigated effects on speech recognition scores in normal-hearing listeners. Study sample: Pre-existing speech recognition data for Experiments 1 and 2; seven normal-hearing participants for Experiment 3. Results: Experiments 1 and 2 demonstrated that kurtosis calculated in the time-domain from noisy speech is highly correlated (r > 0.98) with established prediction models: glimpsing and ESII. All three measures predicted speech recognition scores well. The final experiment showed a clear monotonic relationship between speech recognition scores and kurtosis. Conclusions: Speech recognition performance in noise is closely related to the sparseness (kurtosis) of the noisy speech signal, at least for the types of speech and noise used here and for listeners with normal hearing.

Key Words::

• Glimpsing
• babble
• Speech intelligibility index
• Cocktail party effect

Acknowledgements

This work was supported by an ISVR Raleigh scholarship with partial additional support from Cochlear UK. We thank Martin Cooke for generous help, stimulating discussion, and providing the speech data for the first experiment. Thanks also to TNO Human Factors, Soesterberg, and the Netherlands for providing the babble noise. Thanks also to Koenrad Rhebergen for providing code for the ESII calculations.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.