Music and the Mind

Information on the historical and scientific origins of music and the measurement of music.

From the seventeenth century, many scientists used mathematics to produce further insights into musical theory. Christiaan Huygens (1629-1695) used logarithms to calculate the divisions of an octave, to be used in tuning. Mersenne (1588-1648) estimated the frequency of specific notes by studying the vibration of a heavy wire and Poisson (1781-1840) analysed vibrations in other mediums such as drum skins. 

It was the nineteenth century that saw the standardisation of musical measurement. In 1876, Sturm estimated the speed of sound travelling through water, and found that the speed did not relate to frequency but to the properties of the medium through which it travelled. Standards of pitch were finally decided, like many other standards of measurement, by the French government in 1859. 

These advances meant that in the 20th century researchers could use new instruments and global standards for scientific study and, importantly, that others could reproduce their results.

The growing importance of musical appreciation and skilled performance at this time meant that the human aspect of sound perception was not neglected. Helmholtz (1821-1894) examined the relationship between people's appreciation of aspects such as pitch and timbre and the physical qualities of sound. 

He showed that there was a gap (about 55 milliseconds) between the production of a sound and its psychological realisation in the brain. W C Sabine went back to classical notions in examining the relationship between the physical environment and the appreciation of sound, an issue that was raised in Vetruvius' work on architecture.

Our understanding of the physical basis of sound today does not differ greatly from this historical account.

Sound is produced by vibrations through a medium, which can be air, water or a solid. Vibrations cause waves which travel through the medium until they reach the human ear. These are transferred mechanically through the ear tract to the ear drum, where they are converted to neural messages which travel to the brain. We can then say that the brain senses the sound. Sound, and music, is therefore a combination of mechanical transfer and neurological perception.

Theories on the electronic transmission of sound also need to account for both production and reception. The important breakthrough in this field came in 1948 when Claude Shannon published a paper for Bell Telephone Laboratories on 'A Mathematical Theory of Communication'. The foundation of information theory, this paper attempted to explain communication in terms of a message produced by a source, which is then transmitted through a channel to a receiver. 

The accurate transmission of this message is hampered by 'noise'- any irrelevant information along the chain such as static on the line or distractions. Two things improve the accuracy of transmission: increasing the size of the channel to allow more information across, and exploiting the redundancy of the signal. Redundancy refers to information which is unnecessary or repeated elsewhere. 

In English, for example, you can predict the range of sounds which follow an initial segment and certain combinations of sounds are impossible. Word order is also predictable. This redundancy means that you can reduce the range of sounds transmitted, or have a certain amount of them drowned in static, and still get a meaningful message to the other end