title: Effects of lowpass and highpass filtering on the intelligibility of speech based on temporal fine structure or envelope cues.
abstract: This study aimed to assess whether or not temporal envelope (E) and fine structure (TFS) cues in speech convey distinct phonetic information. Syllables uttered by a male and female speaker were (i) processed to retain either E or TFS within 16 frequency bands, (ii) lowpass or highpass filtered at different cut-off frequencies, and (iii) presented for identification to seven listeners. Psychometric functions were fitted using a sigmoid function, and used to determine crossover frequencies (cut-off frequencies at which lowpass and highpass filtering yielded equivalent performance), and gradients at each point of the psychometric functions (change in performance with respect to cut-off frequency). Crossover frequencies and gradients were not significantly different across speakers. Crossover frequencies were not significantly different between E and TFS speech ( approximately 1.5kHz). Gradients were significantly different between E and TFS speech in various filtering conditions. When stimuli were highpass filtered above 2.5kHz, performance was significantly above chance level and gradients were significantly different from 0 for E speech only. These findings suggest that E and TFS convey important but distinct phonetic cues between 1 and 2kHz. Unlike TFS, E conveys information up to 6kHz, consistent with the characteristics of neural phase locking to E and TFS.
authors: Laboratoire de Psychologie de la Perception, CNRS, Universite Paris Descartes, DEC, Ecole Normale Supérieure, 29 rue d'Ulm, 75005 Paris, France. marine.ardoint@ens.fr
authors: Marine
authors: M
authors: Ardoint
authors: Christian
authors: C
authors: Lorenzi
mesh_terms: D000161:Acoustic Stimulation; D001302:Audiometry, Speech; D001309:Auditory Threshold; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D010700:Phonetics; D010898:Pitch Perception; D011571:Psychoacoustics; D017603:Signal Detection, Psychological; D013065:Speech Intelligibility; D013067:Speech Perception; D013998:Time Perception; D055815:Young Adult