Binaural coherence edge pitch

Abstract

The binaural coherence edge pitch (BICEP) is a dichotic broadband noise pitch effect similar to the binaural edge pitch. The noise is made by summing sine waves with equal amplitudes and random phases. The interaural phase angle is a constant for sine wave components with frequencies below a chosen frequency, and it is a random variable for components with frequencies above that frequency. The chosen frequency is a coherence edge because the signals to the two ears are mutually coherent within any band of frequencies below the edge and they are mutually incoherent in any band above the edge. Sine tone pitch matching experiments show that the BICEP exists for coherence edge frequencies between 300 and 1000 Hz and that it is always matched by a frequency above the edge frequency, by 5%–10%. The effect can be extended to higher edge frequencies, at least 2000 Hz, if the listener is appropriately cued. The results do not depend upon whether the coherent components are presented in phase or completely out of phase to the two ears. For the opposite case, coherence above the edge frequency and incoherence below, the BICEP can be reliably matched only for coherence edge frequencies between 300 and 600 Hz, and the matching frequency is invariably below the coherence edge frequency, by 10%–20%. [Work supported by the National Institutes of Health Grant 17917.]