New experiments beyond the traditional Fourcin Pitch range
Johan Raatgever, Frans A. Bilsen, Reshma Mungra · The Journal of the Acoustical Society of America · 1998
The Fourcin Pitch is a dichotic pitch phenomenon occurring when a white noise signal and its interaurally delayed replica (delay T1) are presented simultaneously with a second (uncorrelated) noise signal with interaural delay T2. Former experiments dealt with T1 between 2 and 10 ms, while T2 was kept at a value between 0 and 2 ms [Bilsen and Wesdorp, 8th ICA (1974)]. With proper polarities of the noises and the delays at opposite ears, the pitch would typically have a value corresponding to 1/(T1+T2) and the (lateralized) pitch image would correspond to the shortest delay (T2). In the present study, both delay times were chosen about equal and with a value above about 5 ms; again the delays were presented at opposite ears, but with equal polarities. It turned out that a pitch is perceived with a saliency estimated between the Fourcin Pitch and the dichotic repetition pitch (one noise source only), with a value corresponding to 2/(T1+T2), and with a (lateralized) pitch image corresponding to an interaural delay of (T1−T2)/2. This new result, also, can be explained by the central spectrum theory [Raatgever and Bilsen, J. Acoust. Soc. Am. 80 (1986)].