Web Audio API

Chapter 3. Volume and Loudness

Once we are ready to play a sound, whether from an AudioBuffer or from other sources, one of the most basic parameters we can change is the loudness of the sound.

The main way to affect the loudness of a sound is using GainNodes. As previously mentioned, these nodes have a gain parameter, which acts as a multiplier on the incoming sound buffer. The default gain value is one, which means that the input sound is unaffected. Values between zero and one reduce the loudness, and values greater than one amplify the loudness. Negative gain (values less than zero) inverts the waveform (i.e., the amplitude is flipped).

theory: Volume, Gain, and Loudness

Let’s start with some definitions. Loudness is a subjective measure of how intensely our ears perceive a sound. Volume is a measure of the physical amplitude of a sound wave. Gain is a scale multiplier affecting a sound’s amplitude as it is being processed.

In other words, when undergoing a gain, the amplitude of a sound wave is scaled, with the gain value used as a multiplier. For example, while a gain value of one will not affect the sound wave at all, Figure 3-1 illustrates what happens to a sound wave if you send it through a gain factor of two.

Figure 3-1. Original soundform on the left, gain 2 soundform on the right

Generally speaking, power in a wave is measured in decibels (abbreviated dB), or one tenth of a ...