sourdine
/sʊrˈdin/
noun
- A mute or damper for a musical instrument, especially a trumpet or other brass instrument, used to soften the sound.
- He removed the sourdine from his horn to let the full sound ring out.
- The trumpeter inserted a sourdine to play a quiet, mellow passage.
- In the orchestra, the brass section used sourdines for the softest part of the symphony.