One who speaks.
Loudspeaker.
Speakerphone.
The chair or presiding officer of certain legislative bodies, such as the U.K. House of Commons or the U.S. House of Representatives.
One who makes a speech to an audience.
A book containing passages of text for use in speeches.
The producer of a given utterance (text, etc), whether actually spoken or e.g. written.
A key on a woodwind instrument of the clarinet family (cf octave key on other instruments) which induces the instrument to overblow.