1. Sound and Silence

Sounds are always surrounding us. From the sound of our heartbeat to the flow of energy through our bodies.

ACOUSTICS is the science that deals with the study of sound. All sounds are waves produced by vibrating objects.

1.1. SOUND, NOISE AND SILENCE

SOUND is a physical phenomenon that is produced when an object vibrates. The vibration is transmitted in the form of sound waves that moves though solids, liquids and gasses(air).

SOUND WAVE

SPEED OF SOUND

The speed of sound depends on physical medium.

Sound waves need to travel through a medium such as a solid, liquid, or gas. The sound waves move through each of these mediums by vibrating the molecules in the matter. The molecules in solids are packed very tightly. Liquids are not packed as tightly as solids. And gases are very loosely packed. The spacing of the molecules enables sound to travel much faster through a solid than a gas. Sound travels about four times faster and farther in water than it does in air. This is why whales can communicate over huge distances in the oceans. Sound waves travel about thirteen times faster in wood than air. They also travel faster on hotter days as the molecules bump into each other more often than when it is cold.

1.2. THE WAY WE HEAR

The ear is the organ that perceives sound.

Sound waves enter through the outer ear from the air and then sound waves move through the ear canal.

Sound waves enter the ear canal and make the ear drum vibrate. This action moves the tiny chain of bones (ossicles – malleus, incus, stapes) in the middle ear. The last bone in this chain ‘knocks’ on the membrane window of the cochlea and makes the fluid in the cochlea move. The fluid movement then triggers a response in the hearing nerve.

NOISE is usually defined as a disagreeable auditory experience, but this is a subjective definition.The physical difference between sound and noise is that sound waves are regular and noise waves are irregular.

Noise pollution is produced when the sound volume is too high. It’s a very common problem in our society and can be harmful to our health. Some of the causes of environmental noise are: transportation, industrial and construction activities, etc. Effects of noise on health include: hearing loss, sleep disorders, stress and aggressive behavior.

SILENCE is the absence of sound or noise. It is an element in music that is as important as sound. Both elements are the basis of musical creation. In music, a rest is the time in which no sound is produced.

Composers use rests to serve different purposes: as a contrast with sounds, as a brief pause between phrases or sections; or as the beginning or end of a musical work.

Some composers such as John Cage have used silence as a major element of their pieces. For example, 4’33'' by John Cage. This piece is made up of silence during 4 minutes and 33 seconds.

1.3. QUALITIES OF SOUND

There are 4 basic qualities of sound:

PITCH (Hz) Low sound/High sound

DURATION (Sec.) Short sound/Long sound

INTENSITY (dB) Soft sound/Loud sound

TIMBRE (Tone Color)

FlipCard Quiz: Qualities of sound review