What is the regular fluctuation of a tone between high and low pitch while playing an instrument called?
vibrato
articulation
tuning
pulse

the regular fluctuation of a tone between high and low pitch while playing an instrument is called vibrato.

Explanation:

Hi, the regular fluctuation of a tone between high and low pitch while playing an instrument is called vibrato.  

Vibrato is a musical effect, most commonly used by guitarists in many genres of music. It consists of a regular fluctuation of the tone of a musical note between high and low pitch (different frequencies).

This fluctuation adds expression to the notes played on an instrument.  

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