In a musical instrument, sound waves build up by constructive interference until they are loud enough to hear. This concept is known as

The right answer to the concept whereby sound waves undergo constructive intereference to producing a louder sound in musical instrument would be superimposition.

Explanation:

When sound waves are produced, especially from a musical instrument, numerous beats are produced, which have different frequencies. The sound waves mix with each other in any of Destructive or constructive interference. When the waves are moving in the opposite direction with the same amplitude, they tend to cancel out each other to produce a quieter sound wave. The constructive interference of sound waves results in a wave with an accumulated amplitude of individual waves, thereby producing a louder sound wave. When sound waves are in combination into a higher amplitude is called superimposition.