+.B backend \fINAME\fR
+Selects the backend use by the speaker process. The following options are
+available:
+.RS
+.TP
+.B alsa
+Use the ALSA API. This is only available on Linux systems, on which it is the
+default.
+.TP
+.B command
+Execute a command. This is the default if
+.B speaker_command
+is specified, or (currently) on non-Linux systems.
+.TP
+.B network
+Transmit audio over the network. This is the default if
+\fBbroadcast\fR is specified.
+.RE
+.TP
+.B broadcast \fIADDRESS\fR \fIPORT\fR
+Transmit sound data to \fIADDRESS\fR using UDP port \fIPORT\fR. This implies
+\fBbackend network\fR.
+.TP
+.B broadcast_from \fIADDRESS\fR \fIPORT\fR
+Sets the (local) source address used by \fBbroadcast\fR.
+.TP