Abstract:

Consonant identification scores were obtained for 18 Dutch consonant phonemes in VCV context, in two experiments in which the narrow-band envelopes of the speech stimuli were manipulated by masking or filtering. For this purpose, the speech stimuli were split up into 26 frequency bands, each one critical band wide. The amplitude envelope of each band, as obtained with a Hilbert transform, was disturbed in two ways: (1) by a narrow-band envelope masker around 4, 8, and 12 Hz, and (2) by notch-band filtering around the same frequencies. Next the speech stimuli were synthesized by using narrow-band noise carriers, each a critical band wide, which were modulated by the aforementioned envelopes. Ten normal-hearing subjects participated in the experiments. The confusion matrices were analyzed by means of multidimensional scaling techniques and compared between the two manipulation methods. The results of the filtering experiment show that consonant recognition scores behave like a low-pass function of notch-width when expressed in octaves. The differences with the results of modulation masking will be discussed, especially with respect to modulation transfer function and consonant recognition cues.