wah-wah
/ˈwɑːwɑː/(亦作wa-wa)
noun
mass noun
1- a musical effect achieved on brass instruments by alternately applying and removing a mute and on an electric guitar by controlling the output from the amplifier with a pedal（铜管乐器和电吉他发出的）“哇哇”声。
1.1
- count noun a pedal for producing such an effect on an electric guitar（电吉他）“哇哇”踏板, “哇哇”声发生器。
词源
1920s: imitative.