fMRI Mapping of Brain Activity Associated with the Vocal Production of Consonant and Dissonant Intervals

Summary

The neural correlates of listening to consonant and dissonant intervals have been widely studied, but the neural mechanisms associated with production of consonant and dissonant intervals are less well known. In this article, behavioral tests and fMRI are combined with interval identification and singing tasks to describe these mechanisms.

Abstract

The neural correlates of consonance and dissonance perception have been widely studied, but not the neural correlates of consonance and dissonance production. The most straightforward manner of musical production is singing, but, from an imaging perspective, it still presents more challenges than listening because it involves motor activity. The accurate singing of musical intervals requires integration between auditory feedback processing and vocal motor control in order to correctly produce each note. This protocol presents a method that permits the monitoring of neural activations associated with the vocal production of consonant and dissonant intervals. Four musical intervals, two consonant and two dissonant, are used as stimuli, both for an auditory discrimination test and a task that involves first listening to and then reproducing given intervals. Participants, all female vocal students at the conservatory level, were studied using functional Magnetic Resonance Imaging (fMRI) during the performance of the singing task, with the listening task serving as a control condition. In this manner, the activity of both the motor and auditory systems was observed, and a measure of vocal accuracy during the singing task was also obtained. Thus, the protocol can also be used to track activations associated with singing different types of intervals or with singing the required notes more accurately. The results indicate that singing dissonant intervals requires greater participation of the neural mechanisms responsible for the integration of external feedback from the auditory and sensorimotor systems than does singing consonant intervals.

Introduction

Certain combinations of musical pitches are generally acknowledged to be consonant, and they are typically associated with a pleasant sensation. Other combinations are generally referred to as dissonant and are associated with an unpleasant or unresolved feeling¹. Although it seems sensible to assume that enculturation and training play some part in the perception of consonance², it has been recently shown that the differences in perception of consonant and dissonant intervals and chords probably depend less on musical culture than was previously thought³ and may even derive from simple biological....

Protocol

This protocol has been approved by the Research, Ethics, and Safety Committee of the Hospital Infantil de México "Federico Gómez".

1. Behavioral Pretest

1. Perform a standard, pure-tone audiometric test to confirm that all prospective participants possess normal hearing (20-dB Hearing Level (HL) over octave frequencies of -8,000 Hz). Use the Edinburgh Handedness Inventory³¹ to ensure that all participants are right-handed.
2. Generation of interval sequences.
   1. Produce pure tones spanning two octaves, G4-G6, using a sound-editing program.
      NOTE: Here, the free, open-s....

Results

All 11 participants in our experiment were female vocal students at the conservatory level, and they performed well enough in the interval recognition tasks to be selected for scanning. The success rate for the interval identification task was 65.72 ±21.67%, which is, as expected, lower than the success rate when identifying dissonant and consonant intervals, which was 74.82 ±14.15%.

In order to validate the basic design of the .......

Discussion

This work describes a protocol in which singing is used as a means of studying brain activity during the production of consonant and dissonant intervals. Even though singing provides what is possibly the simplest method for the production of musical intervals²², it does not allow for the production of chords. However, although most physical characterizations of the notion of consonance rely, to some degree, on the superposition of simultaneous notes, a number of studies have shown that intervals c.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Achieva 1.5-T magnetic resonance scanner	Philips	Release 6.4
Audacity	Open source	2.0.5
Audio interface	Tascam	US-144MKII
Audiometer	Brüel & Kjaer	Type 1800
E-Prime Professional	Psychology Software Tools, Inc.	2.0.0.74
Matlab	Mathworks	R2014A
MRI-Compatible Insert Earphones	Sensimetrics	S14
Praat	Open source	5.4.12
Pro-audio condenser microphone	Shure	SM93
SPSS Statistics	IBM	20
Statistical Parametric Mapping	Wellcome Trust Centre for Neuroimaging	8