Use of a difference in fundamental frequency and spatial location beyond intelligibility purposes

To extract a voice from a background of competing speakers, the human brain exploits voice pitch (harmonic cues) and spatial location (binaural cues) to separate speakers perceptually, and effectively attenuates the background (anything but the target voice). Quieter backgrounds are generally favourable to attentional and memory systems because they free up cognitive resources otherwise spent decoding speech. Therefore, we hypothesize that harmonic and binaural cues have benefits beyond their known contribution to auditory masking release to higher-level cognitive processes, namely short-term recall. To test this, fifty 10-word lists were presented to adult participants with normal hearing in the presence of a non-linguistic masker. Experiment 1 presented words either on the same fundamental frequency (F0) or on different F0 by three-semitones from the masking tone. Experiment 2 presented words either at the same location or differing by 120° from the masking noise. Our results reaffirm that harmonic and binaural cues facilitate speech intelligibility, but there is a cognitive cost to these masking releases. Contrary to our hypothesis, the use of harmonic and spatial cues was associated with a significant detriment to words' recall, once intelligibility was controlled for.