Symbol 5182 from IEC 60417 - Title/Meaning: Sound; audio Function/description: To identify controls or terminals related to audio signals.
Additional information: 
Published in: Supplement B, 1975
Own work using: iso.org/obp/graphics/grs/a3b01424-b38b-41cc-994c-da06e2017310 200.png
Vectorization:  Mrmw