A cognitive and behavioral study: Influence of the tempo on the rhythm perception

Details

Supervisors

Nozaradan

Faculty

Faculté de médecine et médecine dentaire

Degree label

Master [180] en médecine, à finalité spécialisée

Abstract

Listening to music leads to a spontaneous perception of a periodic pulse-like meter. The study of the rhythm can be performed using repetitive musical sequences. There is evidence that specific neuronal populations oscillate when listening to musical sequences, allowing a selective enhancement of metric periodicities. This cross-cultural ability is a cornerstone for rhythmic musical behavior such as dancing. These meter perception phenomena have been investigated and described but remain largely unknown. Here we explore meter perception from a behavioral and neurocognitive point of view using a novel investigation method, "the frequency tagging". Population (P): The study employs healthy participants, free of neurological or auditory problems. Three rhythmic sequences are presented. Each of these sequences are composed of a repeated complex rhythmic pattern (a musical pattern which doesn’t express strong periodicities if played). These rhythmic sequences are varying by their tempo (+ and - 13% from a baseline tempo), with a fast tempo sequence, another medium tempo and finally a slower tempo sequence. Intervention (I): The experiment consists of a listening part. Where we play rhythmic sequences and record the electroencephalogram (EEG). The second part of the experiment consists of a motor task. The participant has to tap according to his own perception of the beat and meter (combined with his internal perception of the rhythm). The participant’s tapping signal is recorded. Control (C): In the listening and motor parts of the experiment, we compare the perception of meter according to the three tempi using a cross-over block scheme. Each block consists of a set of trials played at similar tempi. Each participant listens and taps in a second part of the experiment according to the sequences of the block corresponding to the three tempi. The order in which each block is presented remains random. Outputs (O): The study suggests a temporal scaling of the perception of the meter when the tempo varies in a limited amplitude. The study of the response to small changes in tempo allows us to establish a prototype and to refine our knowledge of the temporal range of the perception of meter. Finally, when the tempo is slightly varied, even in complex musical sequences, the perception of the internal rhythm does not seem to be structurally modified, but there is mostly an adaptation according to the temporal scaling. Research highlights: • People are able to find a coherent meter even for complex pattern’s sequences. • The majority of participants tapped three meters per pattern repetition, regardless of the difference in tempo between conditions; people who tap at this rate are classified as three-tappers. • No significant reorganisation was observed by shifting the tempo in a limited range. The adaptation of the tapping interval (i.e. a temporal scaling)remains coherent with the tempo change, and the tempo variation was not sufficient to cause a drift (major structural reorganization) in the participants’ perception of the meter. • Frequencies associated with the meter perception are enhanced on the EEG response spectrum for each of the three tempi. Three-tapper people (the majority) have three meter related frequencies enhanced compared to the non three meter related frequencies on the EEG response spectrum, suggesting the existence of a neural population that selects and enhances some frequencies regardless of the spectrum of an input signal.