Bass is a low or deep tone (low end frequency) in music. Low or deep tones are also called "low-pitched" tones, because the pitch is low. It is usually made by a bass guitar or an acoustic bass (a double bass). It can also be a deep, rumbling electronic sound made by a synthesizer, a deep singing voice, a baritone sax, or a deep bass drum. Bass gives the well-rounded depth to music. Bass almost always is used with treble sounds made by instruments such as a guitar, piano, a high singing voice, trumpet, or harmonica.