Answer: the regular fluctuation of a tone between high and low pitch while playing an instrument is called vibrato.
Step-by-step 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.
Feel free to ask more if It's necessary.