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Off-key is musical content that is not at the expected frequency or pitch period, either with respect to some absolute reference frequency, or in a ratiometric sense (i.e. through removal of exactly one degree of freedom, such as the frequency of a keynote), or pitch intervals not well-defined in the ratio of small whole numbers.

The term may also refer to a person or situation being out of step with what is considered normal or appropriate.

A single note deliberately played or sung off-key can be called an "off-note". It is sometimes used the same way as a blue note in jazz.[1]

Explanation of on-key[edit]

The opposite of off-key is on-key or in-key, which suggests that there is a well defined keynote, or reference pitch. This does not necessarily have to be an absolute pitch but rather one that is relative for at least the duration of a song. A song is usually in a certain key, which is usually the note that the song ends on, and is the base frequency around which it resolves to at the end.

The base-frequency is usually called the harmonic or key center. Being on-key presumes that there is a key center frequency around which some portion of notes have well defined intervals to.

Deliberate use off-key content[edit]

In jazz and blues music, certain notes called "blue note"s are deliberately sung somewhat flat for expressive effect.

Examples include the words "Thought He Was a Goner" in the song "And the Cat Came Back" and the words "Yum Yum" in the children's song "Five Green and Speckled Frogs."

See also[edit]


  1. ^ Deane L. Root (ed.). "Off-note". Grove Music Online. Oxford Music Online. Oxford University Press. (subscription required)