Raymond E. Slyh

Analysis/synthesis-based microphone array speech enhancer with variable signal distortion

A microphone array speech enhancement algorithm based on analysis/synthesis filtering that allows for variable signal distortion. The algorithm is used to suppress additive noise and interference. The processing structure consists of delaying the received signals so that the desired signal components add coherently, filtering each of the delayed signals through an analysis filter bank, summing the corresponding channel outputs from the sensors, applying a gain function to the channel outputs, and combining the weighted channel outputs using a synthesis filter. The structure uses two different gain functions, both of which are based on cross correlations of the channel signals from the two sensors. The first gain yields the GEQ-I array, which performs best for the case of a desired speech signal corrupted by uncorrelated white background noise. The second gain yields the GEQ-II array, which performs best for the case where there are more signals than microphones. The GEQ-II gain allows for a trade-off on a channel-dependent basis of additional signal degradation in exchange for additional noise and interference suppression.

Microphone array speech enhancement in overdetermined signal scenarios

The problem of enhancing noisy speech by using a microphone array is considered. An algorithm called the graphic equalizer (GEQ) array is presented which trades off signal degradation for additional interference suppression. The algorithm is based on the concept of directly modifying the short-time spectral magnitude of the sum of the received signals. Simulation results are given that illustrate the advantages of using the GEQ array for diffuse-noise scenarios and for scenarios involving more interference signals than array degrees of freedom. The GEQ array was shown to outperform the Frost array for diffuse-noise and overdetermined signal scenarios, in which the Frost array was not capable of attenuating all of the interference with one broad null. While the GEQ array did not always yield a better SNR than the Frost array for these scenarios, it often outperformed the Frost array in terms of the power function spectral distance measure, a measure that is more highly correlated with human auditory perception than is the SNR.<<ETX>>

Perception of stress and speaking style for selected elements of the susas database

The susas database [J. H. L. Hansen and S. E. Bou‐Ghazale, EUROSPEECH 97, 1743–1746 (1997)] is a collection of utterances recorded under conditions of simulated or actual stress, the purpose of which is to allow researchers to study the effects of stress and speaking style on the speech waveform. The aim of the present investigation was to assess the perceptual validity of the simulated portion of the database by determining the extent to which listeners classify its utterances according to their assigned labels. Seven listeners performed an eight‐alternative, forced‐choice, judging whether monosyllabic or disyllabic words spoken by talkers from three different accent classes (Boston, Generic Midwest, New York) were best classified as ‘‘angry,’’ ‘‘clear,’’ ‘‘fast,’’ ‘‘loud,’’ ‘‘neutral,’’ ‘‘question,’’ ‘‘slow,’’ or ‘‘soft.’’ Mean percentages of ‘‘correct’’ judgments were analyzed using a 3 (accent class)×2 (number of syllables)×8 (speaking style) repeated measures analysis of variance. Results indicated t...

Formant estimation using singular value decomposition

The estimation of a small number of damped complex exponentials from data which contain a larger set of damped exponentials and noise is considered. The use of total least squares methods results in biased estimates of the high energy damped exponentials due to the presence of the extra modes. The reasons for this bias, and ways to reduce it, are discussed.<<ETX>>