Inside Macintosh: Sound /

Chapter 4 - Speech Manager / Speech Manager Reference

Speech Manager Routines / Changing Speech Attributes

SetSpeechRate

You can set the speech rate of a designated speech channel with the SetSpeechRate function.

FUNCTION SetSpeechRate (chan: SpeechChannel; rate: Fixed): OSErr;

chan

The speech channel whose rate you wish to set.

rate

The new speech rate for the speech channel, expressed as a fixed-point, words-per-minute value.

DESCRIPTION

The SetSpeechRate function adjusts the speech rate on the speech channel specified by the chan parameter to the rate specified by the rate parameter. As a general rule, typical speaking rates range from around 150 words per minute to around 180 words per minute. It is important to keep in mind, however, that users will differ greatly in their ability to understand synthesized speech at a particular rate based upon their level of experience listening to the voice and their ability to anticipate the types of utterances they will encounter.

SPECIAL CONSIDERATIONS

You can call the SetSpeechRate function at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SetSpeechRate function are

Trap macro	Selector
_SoundDispatch	$0444000C

RESULT CODES

noErr	0	No error
invalidComponentID	-3000	Speech channel is uninitialized or bad