Classi of Speech under Stress Using Target Driven Features", Speech Communication

Speech production variations due to perceptually induced stress contribute significantly to reduced speech processing performance. One approach for assessment of production variations due to stress is to formulate an objective classification of speaker stress based upon the acoustic speech signal. This study proposes an algorithm for estimation of the probability of perceptually induced stress. It is suggested that the resulting stress score could be integrated into robust speech processing algorithms to improve robustness in adverse conditions. First, results from a previous stress classification study are employed to motivate selection of a targeted set of speech features on a per phoneme and stress group level. Analysis of articulatory, excitation and cepstral based features is conducted using a previously established stressed speech database (Speech Under Simulated and Actual Stress (SUSAS)). Stress sensitive targeted feature sets are then selected across ten stress conditions (including Apache helicopter cockpit, Angry, Clear, Lombard effect, Loud, etc.) and incorporated into a new targeted neural network stress classifier. Second, the targeted feature stress classification system is then evaluated and shown to achieve closed speaker, open token classification rates of 91.0%. Finally, the proposed stress classification algorithm is incorporated into a stress directed speech recognition system, where separate hidden Markov model recognizers are trained for each stress condition. An improvement of + 10.1 % and + 15.4 % over conventionally trained neutral an