### ASA 125th Meeting Ottawa 1993 May

## 3pMU2. Hearing melodies in continuous frequency modulations.

**Laurent Demany
**

**
Kenneth L. McAnally
**

**
**
*Lab. de Psychoacoust., Univ. Bordeaux 2, 146 rue Leo-Saignat, F-33076
Bordeaux, France
*

*
*
A 1-kHz carrier was frequency modulated by the exponential of periodic
time functions corresponding to the sum of a few sinusoids (e.g., sin
(omega)t+sin 3(omega)t). The modulations were symmetric on the dimensions of
time and log frequency [y(t)=y(k-t)=-y(k'-t)]. Each had three local maxima and
three local minima per cycle. The peak-to-peak frequency excursion was
typically 0.5 oct. At low rates of modulation, the stimuli were heard as
complex glissandi. However, for modulation rates around 1.5 Hz, the dominant
percept was a melodic motif comprising the pitches of the local maxima.
Generally, the local minima were not heard as auditory ``events'' (pitch
singularities). A similar perceptual asymmetry was not observed for sequences
of discrete tones corresponding to the local maxima and minima of the
continuous modulations. Additional experiments were performed to determine the
frequency difference limens for maxima and minima of continuous frequency
modulations. The carriers were modulated by the exponential of one cycle of a
cosine function, starting at phase (pi) or phase 0. For maxima and minima
around 1 kHz, frequency shifts of maxima were markedly better detected than
frequency shifts of minima. These results are in contrast to those predicted by
consideration of the upward spread of masking.