Updated: May 12, 2020
Volume is a key component in processing sound. How loud or soft is the sound? How does the volume change across time as we listen?
Changes in volume occur naturally with sound, whether this is music, speech or other environmental sounds. We know if a car is coming towards us as the volume will increase as it moves closer. This type of clue is important for keeping us safe.
In terms of speech, an individual speech sound, known as a phoneme, changes in volume as it is produced by the mouth. Some sounds like ‘t’, ‘b’ and others hit a peak of volume quickly and then fade quickly. Other vowel sounds take longer to reach a peak of volume. This is known as rise time. This also happens with different instruments; think of the difference in sound between a percussive instrument such as a piano with the same note that may be produced on a cello. The cello has a much longer rise time. You can see below how the second sound takes longer to reach a maximum volume and then reduces more slowly.