No abstract

Researchers have shown amplitude modulation significantly increases the intelligibility of time-varying sinusoidal (TVS) sentences [T. Carrell and J. Opie, Percept. Psychophys. 52, 437–445 (1992); J. Barker and M. Cooke, Speech Commun. 27, 159–174 (1999)] and ameliorates the effect of multispeaker babble on intelligibility at moderate signal-to-noise ratios [T. Carrell, J. Acoust. Soc. Am. 93, 2327 (1993)]. These effects have been attributed to the ability of amplitude comodulation to create auditory objects. However, other characteristics of acoustic signals cause components to group together, the classic example being sound location in the cocktail party effect [C. Cherry, J. Acoust. Soc. Am. 25, 437–445 (1953)]. In natural environments, acoustic cues work together to assemble and segregate auditory objects for auditory scene analysis [A. Bregman, Auditory Scene Analysis (1990)]. The present study examined the interaction of amplitude modulation and laterality on the intelligibility of TVS sentences in noise. Forty females listened to TVS stimuli in a 2×2×2 factorial design experiment: modulation (100 Hz versus unmodulated) by laterality (diotic versus dichotic) by noise (S/N=+5 dB vs −15 dB). Modulation and noise demonstrated large main effects in the expected direction, but effects of laterality were minimal.