Friday, May 16, 2008

Mac OS X Speech Synthesis

Since the introduction of the Macintosh in 1984 Mac OS has had the ability to convert text into speech. Even eight-bit computers like the Commodore 64 had SAM, an early voice synthesizer, but as I bemoaned several months ago, there has been relatively little progress in speech recognition and synthesis in the intervening decades. For the more than 45 million Americans with literacy problems this is especially important. Despite the lack of exceptional progress, OS X does offer options for text-to-speech that may be of interest to users regardless of their literacy level.

Here are some uses for speech synthesis that you may not have thought of. Anyone who writes, even if it's only an occasional professional email, can benefit from text-to-speech. While spell checkers are great for finding egregious errors, more subtle problems are harder to spot. Often writers inadvertently use the wrong word or add extra words to their text. For example, how often have you seen "you" in place of "your" accidently? One easy way to find these problems is to listen to someone read what you wrote. OS X can do that for you.

Similarly to the Dictionary application, speech synthesis has been integrated into the modern Mac operating system. Any highlighted text whether it be in a web browser or an e-mail, can be read aloud by the computer. In many applications like word processors the user just needs to bring up the context menu by right clicking or control clicking and choose the "Speech" option, and "Start speaking". If the option is not in the context menu it is still available in the Services menu. Click on the name of the application in the menu bar and then go to "Services/Speech/Start speaking". It is also possible to create a shortcut key for this option. Simply go to System Preferences and open the Speech preference pane. In the "Text to speech" tab, check "Speak selected text when the key is pressed" and then push the "Set key" button. Now just highlight text in any application, and your computer will read it to you at the touch of a button.

Another speech feature can be useful to many people. When working on the computer it's easy to lose track of time. Sometimes hours go by before I realize it. To avoid this, OS X can announce the time for you. The option is available in the Date and Time settings. These can be accessed in several ways. There is a button in the aforementioned "Text to speech" pane, or you may click on the time in the menu bar and choose the "Open Date & Time..." option. Date and Time is also a choice from the main System Preferences menu. Once there, simply click "Announce the time", in the Clock tab, choose how often, and click "Customized voice" if you wish to set specific voice options.

Some users like me, who keep their Dock hidden, may not always notice applications bouncing their icons in the Dock when they need attention. This can be addressed by having OS X speak to you when a program needs attention. This option is also in the "Text to speech" tab of the Speech System Preferences. Just check "Announce when an application requires your attention". The computer is even very polite, saying, "Excuse me. Application X needs your attention."

What if you are dissatisfied with the standard computer voices? Without doing an exhaustive search I found two companies that offer commercial voice packs for OS X. Both have fairly realistic voices. You can hear many samples or download demos at the InfoVox and Cepstral web sites. Unfortunately, they're rather pricey. The InfoVox voices are $100 for the American English pack, whereas Cepstral voices are sold individually for $29 each.

While it would be hard to say that speech synthesis has come a long way on the Mac, the availability of universally integrated speech options and high-quality commercial voices does make a compelling combination. For those who prefer to have text read to them or just simple system alerts, text-to-speech can be a useful and important component of the operating system.

For more great information on the Services menu, see this web site.

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