Effect of voice characteristics on the attended and unattended processing of two concurrent messages

Three experiments using dichotic listening measured the priming effect produced on the detection of a semantically defined target word in an attended list of words by a lexically identical word presented to the opposite ear with an attenuation of 12 dB. Experiment 1 embedded the prime in unattended continuous speech and found a 21 ms priming effect, but only when the voices of the two messages had different pitch ranges. Experiment 2 emphasised and generalised the priming effect to a more natural situation using voices differing both in pitch and timbre. This priming effect did not vary with word frequency. In Experiment 3 the prime was part of a list of isolated words played to the unattended ear. It found a 94 ms priming effect when there was no pitch-range difference between the two messages. This priming effect was larger for high-frequency words than for low. These results extend recent findings by Rivenez, Darwin, and Guillaume (2006) and demonstrate the importance of factors that influence perceptual organisation in determining the extent to which unattended messages can be processed.