Preferred Tempo and Low-Audio-Frequency Bias Emerge From Simulated Sub-cortical Processing of Sounds With a Musical Beat.

Nathaniel J Zuk,Laurel H Carney,Edmund C Lalor

doi:10.3389/fnins.2018.00349

Abstract

Prior research has shown that musical beats are salient at the level of the cortex in humans. Yet below the cortex there is considerable sub-cortical processing that could influence beat perception. Some biases, such as a tempo preference and an audio frequency bias for beat timing, could result from sub-cortical processing. Here, we used models of the auditory-nerve and midbrain-level amplitude modulation filtering to simulate sub-cortical neural activity to various beat-inducing stimuli, and we used the simulated activity to determine the tempo or beat frequency of the music. First, irrespective of the stimulus being presented, the preferred tempo was around 100 beats per minute, which is within the range of tempi where tempo discrimination and tapping accuracy are optimal. Second, sub-cortical processing predicted a stronger influence of lower audio frequencies on beat perception. However, the tempo identification algorithm that was optimized for simple stimuli often failed for recordings of music. For music, the most highly synchronized model activity occurred at a multiple of the beat frequency. Using bottom-up processes alone is insufficient to produce beat-locked activity. Instead, a learned and possibly top-down mechanism that scales the synchronization frequency to derive the beat frequency greatly improves the performance of tempo identification.

Highlights

When we spontaneously tap our feet to music, we are “feeling the beat.” A musical beat is frequently defined by the effect it has on motor entrainment (Patel, 2010; London, 2012), and it is often identified as the fundamental level in the metrical hierarchy for keeping time (Lerdahl and Jackendoff, 1983)
Since human perception of musical beats is invariant to the envelope of the stimulus (Henry et al, 2017), these results strongly suggest that neurons with long excitatory and inhibitory synaptic time constants are important for musical beat perception and responsible for biasing the preferred tempo around 100 BPM
Our goal was to quantify tempo induction performance based on the simulated sub-cortical neural activity to directly identify the mechanisms necessary to “feel the beat” in music

Summary

Introduction

When we spontaneously tap our feet to music, we are “feeling the beat.” A musical beat is frequently defined by the effect it has on motor entrainment (Patel, 2010; London, 2012), and it is often identified as the fundamental level in the metrical hierarchy for keeping time (Lerdahl and Jackendoff, 1983). When we spontaneously tap our feet to music, we are “feeling the beat.”. A musical beat is frequently defined by the effect it has on motor entrainment (Patel, 2010; London, 2012), and it is often identified as the fundamental level in the metrical hierarchy for keeping time (Lerdahl and Jackendoff, 1983). Many cultures have music with a beat, and the presence of beat-based music is highly related to communal dance (Savage et al, 2015). Perceiving the beat is key to the perception of music. In many genres of music, musical beats often, but not always, occur at isochronous intervals (London, 2012). Previous models have simulated the perception of isochronous beats using an

Objectives

Methods

Results

Conclusion