Binaural factors in auditory continuity

Auditory continuity is a powerful illusion which has implications for the efficient coding of sound. Although auditory continuity has been studied extensively as a monaural phenomenon, there have been few reports of the influence of binaural factors. Hartmann [1] and Kashino & Warren [2] report that when a tone alternates with a noise, the continuity threshold of the tone is lower when the tone and noise differ in their interaural timing. Here we aconfirm the binaural contribution to continuity continuity using Huggins pitch [3]. We alternate a Huggins-pitch noise (target) with a negative-phase Schroeder complex (inducer) and find that pulsation thresholds are lower when listeners judge continuity of the pitch percept within the Huggins noise, than when they judge continuity of the noise itself. We also demonstrate that binaural continuity is determined by the relative ITDs of the targe and inducer rather than by their perceived spatial positions and introduce a simple model to account for our findings, which assumes that the tone is heard as pulsating if there is a detectable dip in the output of either of three channels: two monaural [4] and one binaural channel.