This function returns the voice name of a specific speaker client (host or host:instance).
Parameter: host
Type: string
Description: Leaving this a null string will return the voice name for
the first instance HomeSeer finds, otherwise use the hostname of the computer
you are interested in determining the voice name being used. If
more than one instance of the Speaker application is running on "host"
then you may need to specify the instance as well in the format host:instance.
Return value: voice
name
Type: string