Clarisse Baruch

Tempo discrimination in infants

An habituation/dishabituation paradigm demonstrates that 2- and 4-month-old infants are able to discriminate auditory sequences that vary slightly in tempo. Discriminations were only observed for intermediate tempi (600 ms but not 100, 300, 1500 ms IOI), suggesting that infants have the same optimal tempo range as adults.

Loudness reduction and adaptation induced by a contralateral tone

An intermittent tone in one ear may induce a large decline in the loudness of a continuous tone in the contralateral ear [Botte et al., J. Acoust. Soc. Am. 72, 727-739 (1982)]. To uncover the basis for this induced loudness adaptation, the method of successive magnitude estimations was used to measure the loudness of a test tone in one ear during and after a single presentation of a brief inducer tone in the contralateral ear. Duration and frequency of the inducer were varied. The frequency of the test tone was set at 500, 1000, or 3000 Hz. Both inducer and test tones were at 60 dB SPL. When the inducer lasted 5 s or more and was at the same frequency as the test tone, the loudness of the test tone was reduced by 80% to 100% while the inducer was on. As the inducer frequency moved away from the test tone, the loudness reduction declined gradually except for a more marked drop at the point where the frequency separation exceeded the critical bandwidth. Loudness remained depressed after the inducer went off. Additional measurements showed that the amount of loudness reduction corresponded closely to the measured movement of the inducers sound image away from the center of the listeners head (decentralization).

Tempo sensitivity in auditory sequences

Differential thresholds for 11 tempi (ranging from 100 to 1500 ms between successive onsets) were measured for four subjects using a 2AFC paradigm. In a first experiment, the number of events in the sequence was varied to test whether sensitivity is greater in regularsequences than in simple duration discrimination tasks (only two events). Relative jnd were: (1) optimal at intermediate tempi (as low as 1.5% in the range between 300–800 ms), and (2) decreased as the number of events increased (2 events=6%, 3 events=4%, 5 events=3.2%, 7 events=3%). A second experiment tested whether this higher sensitivity was due to the fact that the sequences were regular or not by measuring differential tempo thresholds for irregular sequences of five events. Globally, sensitivity for these irregular sequences was of an intermediate level between that of the simple duration task and the sequences with five regular events. The results are discussed in terms of the hypothesized ‘‘regularity detectors.’’

Memory for Loudness: the Role of Loudness Contour

The study aimed at understanding the loudness memory and especially at testing the hypothesis that the loudness contour of a tone sequence influences differential sensitivity -over a long lapse of time- in the domain of intensity. In the first experiment, the loudness of a first reference tone had to be reproduced after a delay (.5, 2, 10, or 20 s) by adjusting the level of a second tone. Errors of adjustment depended on the initial level of the second tone and on the delay. In the second experiment, subjects compared two tones separated by silences. For delays of .5 and 2s, the best performance was found for comparison levels equal to or lower than the reference. In the third experiment, the tones to be compared were separated by 6 interpolated tones at different levels. For sequences with increasing and decreasing levels, the opposite shifts of sensitivity which were observed could explain the adjustment bias of the first experiment. Moreover, only interpolated contours having components at least 6 dB higher than the reference provide a significant impairment of the performance. These results suggest a “retroactive masking” of the memorized trace by subsequent louder sounds.

Loudness Adaptation in Children

Simple loudness adaptation was measured for a steady tone presented alone at 10 dB SL; contralaterally induced adaptation was measured for a steady tone in one ear accompanied by an intermittent tone in the contralateral ear; ipsilaterally induced adaptation was measured for a tone increased intermittently by 15 dB. The method of successive magnitude estimation revealed no differences between 12 adults and 36 children from 9 to 14 years of age in the amounts of adaptation over a 3-min exposure. A second set of experiments with a new group of 20 adults and 20 children used a Békésy tracking procedure to reach similar results. Unlike Kärjä [Acta Oto-Laryngol 1968; (suppl)241:1-56], who found significant adaptation in only 5 of 29 children and much adaptation in most adults, we found considerable adaptation in children as well as in adults.

The Rhythmic Web of Fantasy

Dominique Cupa posits the existence of a “web” (trame), generated by the unconscious ego, that is constitutive of fantasy. Starting from Freud and the accent he places on the perio¬dicity of the intake of information from the external world, the author proposes that psychic structuring based on a representation of linear time, constructed by the ¬preconscious on pulsation and taken over by the unconscious ego, allows fantasy activity to be deployed.