Jazz vocal improvisation sometimes uses nonsense syllables to make new melodies. this technique is called:
a. scat singing.
b. wailing.
c. screaming.
d. aria.

a.scat singing.

Explanation:

    Although few people know what it is, you have probably heard a scat singing. It is a feature, widely used by jazz singers, which consists of improvising syllables and meaningless words in the middle of the music to create a sound similar to that of an instrumental solo.