alert-hexagon-off
alert-small-off
alert-square-rounded-off
speaker-none
speaker-simple-none
speaker-simple-slash
speaker-simple-x
speaker-slash
speaker-x
speaker-none-fill
speaker-simple-none-fill
speaker-simple-slash-fill
speaker-simple-x-fill
speaker-slash-fill
speaker-x-fill
All under MIT or ISC license - free for your personal and commercial projects.