title: Across-formant integration and speech intelligibility: Effects of acoustic source properties in the presence and absence of a contralateral interferer.
abstract: The role of source properties in across-formant integration was explored using three-formant (F1+F2+F3) analogues of natural sentences (targets). In experiment 1, F1+F3 were harmonic analogues (H1+H3) generated using a monotonous buzz source and second-order resonators; in experiment 2, F1+F3 were tonal analogues (T1+T3). F2 could take either form (H2 or T2). Target formants were always presented monaurally; the receiving ear was assigned randomly on each trial. In some conditions, only the target was present; in others, a competitor for F2 (F2C) was presented contralaterally. Buzz-excited or tonal competitors were created using the time-reversed frequency and amplitude contours of F2. Listeners must reject F2C to optimize keyword recognition. Whether or not a competitor was present, there was no effect of source mismatch between F1+F3 and F2. The impact of adding F2C was modest when it was tonal but large when it was harmonic, irrespective of whether F2C matched F1+F3. This pattern was maintained when harmonic and tonal counterparts were loudness-matched (experiment 3). Source type and competition, rather than acoustic similarity, governed the phonetic contribution of a formant. Contrary to earlier research using dichotic targets, requiring across-ear integration to optimize intelligibility, H2C was an equally effective informational masker for H2 as for T2.
authors: Psychology, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, United Kingdom.
authors: Robert J
authors: RJ
authors: Summers
authors: Department of Psychology, University of York, Heslington, York YO10 5DD, United Kingdom.
authors: Peter J
authors: PJ
authors: Bailey
authors: Psychology, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, United Kingdom.
authors: Brian
authors: B
authors: Roberts
mesh_terms: D000161:Acoustic Stimulation; D006801:Humans; D010700:Phonetics; D011897:Random Allocation; D013061:Speech Acoustics; D013065:Speech Intelligibility / Q000502:physiology*; D013067:Speech Perception