François-Xavier Féron

Upper limits of auditory rotational motion perception

Three experiments are reported, which investigated the auditory velocity thresholds beyond which listeners are no longer able to perceptually resolve a smooth circular trajectory. These thresholds were measured for band-limited noises, white noise, and harmonic sounds (HS), and in different acoustical environments. Experiments 1 and 2 were conducted in an acoustically dry laboratory. Observed thresholds varied as a function of stimulus type and spectral content. Thresholds for band-limited noises were unaffected by center frequency and equal to that of white noise. For HS, however, thresholds decreased as the fundamental frequency of the stimulus increased. The third experiment was a replication of the second in a reverberant concert hall, which produced qualitatively similar results except that thresholds were significantly higher than in the acoustically dry laboratory.

Tracking the composer’s cognition in the course of a creative process: Stefano Gervasoni and the beginning of Gramigna

Studies of composers’ cognition are restricted by the methodological and epistemological problems with which they are associated. In order to capture the cognitive processes involved in the elaboration of an instrumental piece by Stefano Gervasoni entitled Gramigna (2009-), the authors developed different strategies for composition simulations, which were filmed in order to collect rich and structured data. These methods draw upon the precompositional documents established by the composer over the course of his creative activity, by requesting that he re-enact the operations that generated the documents and the final work. The article focuses on the first movement of Gramigna, composed in a single day, several months before this study began. During a “compositional situation simulation interview”, the composer sat before his manuscript in order to induce his recollection, simulation and verbalisation of the completed creative act. The study’s methodological and epistemological principles (including their advantages and limits) are presented first, followed by a detailed reconstruction of the composer’s action/cognition during the writing of the manuscript. This procedure highlights the sequence of Gervasoni’s significant compositional operations and allows us to categorise and formalise the most salient features of his compositional process. These include the creation of locally applicable construction rules, the placement of concurrent rules, the attention paid to irregularities in the formalistic systems employed and tactics that blur notions of referentiality.

Auditory velocity discrimination in the horizontal plane at very high velocities

We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288°/s and 720°/s in an acoustically treated room and Experiment 2 used velocities between 288°/s and 576°/s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Webers law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation.