EFFECTS OF FREQUENCY AND AMPLITUDE-MODULATION ON THE PITCH OF A COMPLEX TONE WITH A MISTUNED HARMONIC

It has previously been found that when a single low-numbered harmonic of a complex tone is progressively mistuned, for mistunings up to abou t 3%, the pitch of the complex changes in the direction of the mistuni ng but for larger mistunings (by about 8%) the pitch returns to its or iginal value. This result is compatible with the operation of a mechan ism such as a graded harmonic sieve, which can reject from the calcula tion of pitch those frequency components that are implausibly distant from a harmonic frequency. The first experiment shows that the toleran ce of such a sieve is increased when all the components of the complex tone (including the mistuned component) share a common pattern of fre quency modulation at a rate of 6 Hz. The second experiment shows that the tolerance of the sieve is not increased when the components share a common pattern of amplitude modulation at 17 Hz. The third experimen t replicates these findings and further shows that the increase in sie ve tolerance for FM, but not for AM, occurs at both 6 and at 17 Hz.