75fc1dc0_ine___Music_Dictionary_Tp___Tr__description
[name] Harmon mute harmon; other instructions are 'stem out', 'remove stem' and 'waa-waa' (+ = shut, o = open) [description] 
metal mute wrapped in cork and inserted into bell of trombone. The mute has a stem which is normally fully inserted, but may be pulled out or removed entirely. A 'waa-waa' effect may also be achieved by using the hand to cover and uncover the stem opening
Dolmetsch Online - Music Dictionary Tp - Tr
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