Cocktails for Franssen: Asynchronous transient bias and other attentional factors in auditory localization

Abstract

The cocktail-party paradigm was applied to nonspeech signals. Pure-tone stimuli were used in an extension of the Franssen effect, an auditory illusion wherein the location of a slow-onset signal is perceived to be the same as a simultaneous, contralateral sudden-onset signal. Listeners heard simultaneous sudden-onset (transient) and contralateral slow-onset (steady-state) tones in a reverberant environment with a second delayed transient from a third azimuthal location. Results showed that the Franssen effect was either maintained or ‘‘reset,’’ but not reduced. The ongoing steady-state tone was perceived either at the initial-transient and then delayed-transient location, or at the initial transient location only. None of the listeners showed a location bias to the delayed transient tone when its frequency differed from the initial signal frequency or was replaced with noise. In additional conditions based on the ‘‘false Haas effect,’’ consonant–vowel pairs representing transient and steady-state signals were segregated contralaterally in a reverberant space. Results showed no resemblance to the Franssen effect. In general, results indicated that the role of attention is fundamental to the localization of an ongoing stimulus. [Work supported by NIH.]