Symbol 5436 from IEC 60417 - Title/Meaning: Sound muting Function/description: To identify the control for suppressing the sound.
Additional information: 
Published in: Supplement M, 1994
Own work using: iso.org/obp/graphics/grs/0603cbb6-35c9-4a4e-b831-e9c2d92b0a0d 200.png
Vectorization:  Mrmw