Invention

Part 20 - Music

Above Garry Burton (vibraphone) and Chick Corea (vibraphone and grand piano)

About 200 million years ago, the first mammals, our remote ancestors, were tiny, nocturnal insectivores. On a black night, they needed an acute sense of hearing to discriminate between the rustle of leaves and the mating call of a succulent bug.   We have inherited this ability and can hear sounds transmitted by high frequency changes in air pressure measured as cycles per second or Hertz (Hz). This vibrates our ear drum and the brain recognizes frequencies from about 20 Hz up to 16000 Hz. Our brains can even locate the direction of the sound by the infinitesimal time differences between our two ears.

The human ear is incredibly sensitive to small differences in frequency. For moderate loudness levels, we can detect a frequency change of about 1 to 3 Hz for frequencies up to about 1000 Hz.

Between 1.9 and 0.5 million years ago, our ancestors, Homo erectus and Homo ergaster, evolved a brain size (cranial capacity) of 1000 cm3 (cubic centimetres) implying the phenomenal addition of 125,000 more neurons with each generation. This increase was possibly driven by evolution of the larynx together with changes to the tongue, lips and mouth cavity that made possible articulate speech. We almost certainly started singing when the human larynx evolved the ability to vibrate, with incredible precision, sometime between 350 and 150 thousand years ago.

The range of the female voice is from 350 Hz to 3000 Hz but harmonics can range up to 17000 Hz. The male voice ranges from 100 Hz to 900 Hz with harmonics to 8000 Hz. (A harmonic or overtone is a vibration that is a multiple of the frequency of the original (fundamental) tone).

There is no obvious evolutionary reason why music is a feature of every human culture, except perhaps that, like drumming, it makes people happy so that they tend to stick together and survive long enough to raise children. The human brain is enchanted by the complex intermingling of rhythmic, musical sounds and simply listening can produce feelings ranging from mild pleasure to ecstatic joy. 

Almost everyone is captivated by music. As William Congreve wrote in his play, The Mourning Bride, 'Music hath charms to soothe a savage breast. To soften Rocks, or bend a knotted Oak.'

Oh Fortuna from Carmina Burana by Karl Orff 

People have been inventing musical instruments since someone noticed that blowing into a hollow bone or a bamboo tube produced a musical sound. The oldest instruments found so far, were flutes made from bird bones about 42,000 years ago. Early hunters probably used this skill to mimic bird and animal sounds. They may have entertained one another by mimicking bird song which may have introduced the art of singing. Mothers must have sung as a way to pacify their fractious infants. 

Evolution provided young children the defensive ability to emit a high pitched shriek, audible for some distance, which may have prompted people to whistle by vibrating the lips or tongue. 

The earliest musical instruments, apart from drums, were probably small cylinders or spherical cavities capable of producing a piercing note when air was blown across the edge. (The bosun's pipe is still used on naval ships today).The earliest use of musical instruments may have been to coordinate hunting or actions during warfare. Until the last century, musicians and military bands were traditionally used to reassure and encourage infantry marching into battle.

In flutes, air is blown through pursed lips (the embouchure) to pass over a sharp edge. The note is determined by the length of the tube. Notes of higher frequencies can be made by removing one or more fingers covering holes along the length of the tube. In reed instruments, such as clarinets and saxophones, the vibration is created by blowing air past a reed causing it to vibrate.

In aerophones such as trumpets, French horns, tubas and trombones, the lips themselves provide the vibration. Most of these 'brass' instruments have valves to alter the frequency range but the trombone is commonly built with a slide section that permits infinite adjustments to the pitch (frequency).Vibrating strings can also vary the pitch while producing a pleasing sound especially when connected to a wooden box that amplifies the sound. These instruments include harps, the violins, guitars and pianos.

With harps and guitars the string is made to vibrate by plucking. Violin strings vibrate normally when a bow is drawn across the string to produce a continuous note but the strings can also be plucked. In pianos the strings are struck with small hammers. Percussion instruments began when drummers noticed that pieces of wood or bone produced a musical sound when tapped and built instruments like the xylophone. 

The first vibraphone was sold by the Leedy Manufacturing Company in the United States in 1921. But this was improved in 1927 by Henry Schluter and more recently with the addition of resonating tubes.

The lowest frequency on a piano is 27.5 Hz, which is nearly at the bottom of the human hearing range. But, the highest frequency is only 4186.01 Hz (far lower than the audible maximum of about 17 000 Hz) because our ears are less able to discriminate the higher harmonic vibrations produced by each note, so the highest notes do not sound so musical.

 Mars.   The Planets by Gustav Holst