Audio Engineering Society UK

Title: When All the Songs Sound the Same: Insights into the Musical Brain
Location: Royal Academy of Engineering, London
Description: Lecture by Dr Lauren Stewart, Goldsmiths University, London
Start Time: 19:00
Date: Thursday 10th June 2010

A recording of the lecture is available here (69MB mp3)

Abstract

The ability to make sense of musical sound has been observed in every culture since the beginning of recorded history. In early infancy, it allows us to respond to the sing-song interactions from a primary caregiver and to engage in musical play. In later life it shapes our social and cultural identities and modulates our affective and emotional states. But a few percent of the population fail to develop the ability to make sense of or engage with music.  The study of disordered musical development sets in sharp relief the perceptual and cognitive abilities which most of us take for granted and give us a unique chance to investigate how musical perceptual ability develops, from the level of the gene to the brain development and the emergence of a complex and fundamental human behaviour.

Lecture report

For most of us, music forms an integral part of our lives. Even if we’re not music fans as such we still associate particular pieces of music with events or period in our lives, memories of which are evoked when we hear them. More than that, across all cultures since the beginning of recorded history music has played a role in the raising of children and in adult cultural interaction.

But a minority of people, suffering from a condition termed amusia, are unable to perform the sophisticated processes of analysis and prediction that make up human musical enjoyment. Amusia can result from brain injury but in the form of congenital amusia – the condition that Dr Lauren Stewart of Goldsmiths, University of London, is studying and described in this lecture – is apparently a genetic condition passed from parent to child. Certainly, familiar cases of amusia are common.

Amusia was first described in a case report by Grant-Allen in 1878, who noted that the patient concerned required two sounds to have an unusually large pitch differential for that difference to be perceived, and that the perception of octave equivalence and differentiation of consonance and dissonance were missing. Isabelle Peretz of the University of Montreal named congenital amusia in 2003 and developed the Montreal Battery for the Evaluation of Amusia (MBEA), a series of tests to probe subjects’ impairment with respect to six different aspects of musical form: scale, contour, interval, rhythm, metre and memory. He also gathered normative data from non-affected subjects. This work showed that amusia is not merely an inability to sing but a symptom of a primary perceptual problem.

Lauren Stewart’s research in this field began with the creation of an online screening test at the University of Newcastle upon Tyne to identify subjects with amusia, which has now been completed by more than 170,000 people (www.delosis.com/listening/home.html). A normal score in the test is 26 or 27 out of 30; subjects who scored 21 or lower were identified as amusic and invited to attend a full battery of tests. A total of 40 people agreed, and control subjects then matched for age and musical background. Questions the research hopes to address are:

1) What is the core underlying deficit (or deficits if more than one)?
2) Are there implications outside the musical domain, eg for speech perception?
3) Does musical appreciation depend upon intact perception?
4) Given that this is a genetic condition, are there brain structural correlates?

The detailed testing has shown that amusics’ difficulties do not arise from a pitch discrimination deficit – they are able to detect a pitch difference of a semitone – but they do perform less well than normal subjects on pitch direction tests. This ability to perceive the direction in which pitch changes is essential to distinguishing one tune from another. Thresholds for the detection of intensity change are currently being measured, initial results suggesting that amusics have a higher threshold – so their ‘contour’ problem may involve more than a shortfall in pitch direction discrimination.

Amusics perform well on speech perception, which has led to the suggestion that there may be a different pitch mechanism for speech and music. But the difference may also be explained by amusics being able to ‘tag’ certain words, which they listen out for. A new experiment using normal speech, gliding tones and natural speech has confirmed that amusics have difficulty with discrimination of subtle pitch changes. This may represent less of a problem with non-tonal languages like English than with tonal languages like Chinese, where pitch varies rapidly within words and sentences, making pitch discrimination more important.

Although amusics generally use music less than control subjects, there is overlap between the groups with about a third of amusics using music as much as the controls. This might suggest the existence of different sub-groups of amusics but it has been observed that those who use music more in fact have similar perceptual deficits but are younger. So there may be a socio-cultural explanation, younger amusics using music for its associations rather than for enjoyment of the music itself. Or it could be that some amusics have problems with timbre as well as pitch, making appreciation of music more difficult still.

Structural neuroimaging studies have confirmed subtle difference in brain structure between the amusic and control groups, with both the frontal and temporal lobes displaying differences in grey matter density. Functional studies have shown that the frontal cortex is recruited for complex pitch discrimination tasks, so these structural differences may well be associated with amusics’ pitch perception difficulties. It appears that crucial connections are weaker in amusic subjects.

In closing out this fascinating lecture and inviting questions from the floor, Dr Stewart recommended David Huron’s book ‘Sweet Anticipation: Music and the Psychology of Expectation’ to those interested in learning more about current understanding of the perception of music. In this book Prof Huron, head of Ohio State University’s Cognitive and Systematic Musicology Laboratory, expands on the role of expectation in musical appreciation.

Report by Keith Howard

A brief description of congenital amusia, written by Dr Stewart, is available here.

Dr Stewart is Senior Lecturer and director of a new MSc course: Music, Mind and Brain at Goldsmiths, University of London

Lauren originally studied Physiological Sciences at Balliol College Oxford, but transferred from bodies to brains with an MSc in Neuroscience and doctoral and postdoctoral training at the Institute of Cognitive Neuroscience, the Wellcome Department of Imaging Neuroscience (both UCL) and Harvard Medical School.

Her current research interests ranges from studying those with congenital amusia who have an inability to make sense of musical sound to studying the acquisition of perceptual, cognitive and motor skills in trained musicians.