It's a logo of a microphone. The microphone is the old style that radio announcers of the thirties might have used. There is a slash over the microphone that would indicate that a microphone is either not available or is not allowed for use.
This is a Mute Unmute icon. We've made it in iOS style
, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 13,900 icons, all in the same style and quality.