AUDITORY BABBLE AND COGNITIVE EFFICIENCY - ROLE OF NUMBER OF VOICES AND THEIR LOCATION

Four experiments investigated the disruptive effect on short-term memory of irrelevant babble speech. With monaural presentation, 1 voice and 2 voices produced roughly the same degree of disruption, but babble of 6 voices reduced errors significantly. The same pattern was shown when the speech was in a language that the participants did not understand. As the number of voices in the babble was increased from 1 to 6, the function relating the number of voices to errors was monotonic only over part of the range. Allocating each voice to a different spatial location restored its disruptive capacity, compared with a condition where 6 voices came from the 1 location. In practice, the disruptive effect of irrelevant speech will be less where the number of voices is greater (such as in large office spaces), but acoustic conditions that help localization of individual voices will increase disruption.