Hum (sound)

Hum (sound)

A hum is a sound made by humming a wordless tone with the mouth opened or closed, forcing the sound to emerge from the nose. To hum is to produce such a sound, most often with a melody. It is difficult to hum with your nose pinched closed for more than a few seconds. It keeps the volume at a low level, so humming is rarely used in musical productions, with some exceptions such as scat singing and vocables. Humming is sometimes used to keep the melody when the singer does not know the lyrics.

A hum has a particular timbre (or sound quality), usually a monotone or with slightly varying tones. There are other similar sounds not produced by human singing that are also called hums, such as a sound produced by machinery in operation or by an insect in flight. The hummingbird was named for the sound that bird makes in flight.