The Speech Manager uses the Component Manager to access whatever speech synthesizers are available and allows applications to take maximum advantage of a computer's speech facilities without knowing what those facilities are. More Macintosh Toolbox , but you do not need to be familiar with it to use the Speech Manager. A speech synthesizer can include one or more voices, as illustrated in Figure 0-14 . Just as different people's voices have different tonal qualities, so too can different voices in a synthesizer. A synthesized voice might sound male or female, and might sound like an adult or child.
Some voices sound distinctively synthetic, while others sound more like real people.
As speech synthesizing technology develops, the voices that your application can access are likely to sound more and more human. Because the Speech Manager's routines work on all voices and synthesizers, you will not need to rewrite your application to take advantage of improvements in speech technology. Any given person has only one voice, but can alter the characteristics of his or her speech in a number of different ways. For example, a person can speak slowly or quickly, and with a low or a high pitch. Similarly, the Speech Manager provides routines that allow you to modify these and other speech attributes, regardless of which voice is in use.