What do you call a technique in which a singer performs using techniques to imitate instrumental sounds?

The technique in which a singer uses their voice to imitate instrumental sounds is known as scat singing. This style involves a form of vocal improvisation where the singer uses nonsensical syllables and sounds rather than actual lyrics. Scat singing often mimics the rhythms and melodies of instruments found in jazz and can create intricate vocal lines that resemble the sound of a horn or a saxophone. The emphasis is on expression, creativity, and the playful use of the voice as an instrument, making it a unique and impactful technique within jazz music.

Other options do not fit the description as closely. For example, rap primarily focuses on spoken or chanted rhythmic lyrics rather than imitating instrumental sounds. Whistling is an entirely different vocalization that is not focused on improvisation in the context of imitating instruments. Vocal fry is a vocal quality or technique characterized by a low, creaky voice, but it does not involve imitating instrumental sounds. These distinctions clarify why scat singing is the correct choice.