Frequency in the Musical Context
At the very basic level, sounds of music are made up of primarily two different properties. Both properties are directly related to the vibration of soundwaves. These properties are Frequency and Amplitude. This article will focus on Frequency.
To learn more about Amplitude click here.
To understand Frequency, one must first understand what a soundwave is. The soundwave is made up of vibrations that go through cycles over time.
Here is a diagram of a single cycle in a soundwave:
These cycles are referred to as Hertz (or Hz) which is a unit of frequency. One Hertz is equal to one cycle per second. For perspective, the note Middle C (of C4) on a piano is 261.63 cycles per second or simply, 261.63 Hz. In music, each pitch (Ab, A, Bb, B, etc.) has its own frequency.
As one increases the Hertz of a sound wave, the pitch will sound higher. Doing the opposite, lowering the Hertz, will cause the pitch to sound lower. For example, an A5 (880 Hz) on the piano will sound much higher than a C2 (65.41 Hz).
At a physics point of view Hertz is the speed of a wave (c) divided by its wavelength (λ).
Frequency = (Velocity)/(Wavelength)
f = c / λ