What is Sound?
Sound is a vibration or a series of vibrations that move through the air.
Anything that creates the vibrations, or waves, is referred to as the source
The source can be a string, a bell, a voice, or anything that generates a
vibration within our hearing range.Imagine dropping a stone in water.
The stone (source) will create a series of ripples in the water.
The ripples (waves) are created by areas of dense molecules that are being
pushed together as sparse molecules expand, thus creating flatter areas.
Sound travels just like this, by compression and rarefaction.
Compression is the area dense molecules are pushed together
and rarefaction is the area where fewer molecules are pulled apart,
or expanded, in the wave.
The compression area is higher in pressure and the rarefaction area is
lower in pressure.This chapter deals with the seven characteristics of a
sound wave, such as amplitude, frequency, phase, velocity, wavelength, harmonics, and envelope.
Understanding these characteristics is essential to make a decent
recording, become a competent mix engineer, and generally increase your
knowledge about audio.
the sine wave is often used to illustrate a sound wave
and its seven characteristics.
Seven Characteristics of Sound
Although a typical sound is more complex than a simple sine wave,
You may already know about amplitude and frequency.
If you have ever adjusted the tone on your amp or stereo, then you have
turned up or down the “amplitude” or a “frequency” or range of frequencies.
It is necessary to understand these two important sound wave
characteristics, as they are important building blocks in audio engineering.
Two other characteristics of sound help humans identify
one sound from another: harmonics and envelope. The remaining three
characteristics of sound are velocity, wavelength, and phase.
These characteristics identify how fast a sound wave travels, the physical
length of a completed cycle, and the phase of the sound wave.