Effects of noise suppression on intelligibility. II: An attempt to validate physical metrics.

Using the data presented in the accompanying paper [Hilkhuysen et al., J. Acoust.

Effects of noise suppression on intelligibility: experts' opinions and naive normal-hearing listeners' performance.

Purpose: In this study, the authors investigated how well experts can adjust the settings of a commercial noise-reduction system to optimize the intelligibility for naive normal-hearing listeners.

Method: In Experiment 1, 5 experts adjusted parameters for a noise-reduction system while aiming to optimize intelligibility. The stimuli consisted of speech presented in car-cabin noise or babble at 5 different signal-to-noise ratios (SNRs).

Effects of noise suppression on intelligibility: dependency on signal-to-noise ratios.

The effects on speech intelligibility of three different noise reduction algorithms (spectral subtraction, minimal mean squared error spectral estimation, and subspace analysis) were evaluated in two types of noise (car and babble) over a 12 dB range of signal-to-noise ratios (SNRs). Results from these listening experiments showed that most algorithms deteriorated intelligibility scores. Modeling of the results with a logit-shaped psychometric function showed that the degradation in intelligibility scores was largely congruent with a constant shift in SNR, although some additional degradation was observed at two SNRs, suggesting a limited interaction between the effects of noise suppression and SNR.

Statistical analysis of the autoregressive modeling of reverberant speech.

Hands-free speech input is required in many modern telecommunication applications that employ autoregressive (AR) techniques such as linear predictive coding. When the hands-free input is obtained in enclosed reverberant spaces such as typical office rooms, the speech signal is distorted by the room transfer function. This paper utilizes theoretical results from statistical room acoustics to analyze the AR modeling of speech under these reverberant conditions.