The System Preferences application is an important tool you use to control how your Mac OS X system works and looks. If you have read through other parts of this book, you have already used some of the panes it contains to work with various parts of the system. Table 8.1 provides a summary of each pane and tells you where in this book you can learn more about it.
What It Does
Where You Can Learn More About It
Sets interface colors, scrollbar behavior, the number of recent items, and font smoothing
"Setting Appearance Preferences," p. 209
Desktop & Screen Saver
Sets the background image of the desktop and configures the screen saver you use
"Customizing the Mac OS X Desktop," p. 121;
"Using the Mac OS X Screen Saver," p. 212
Controls how the Dock looks and works
"Customizing the Appearance and Behavior of the Dock," p. 138
"Managing Open Windows with Exposé," p. 98
Controls the language and formats used depending on the language you are working with
"Setting International Preferences," p. 210
Configures FileVault and other security settings
"Securing Your Mac with the Security Pane," p. 897
Configures Bluetooth services on your Mac
"Finding, Installing, and Using Bluetooth Devices," p. 735
CDs & DVDs
Configures the actions that occur when you insert CDs or DVDs
Chapter 24, "Understanding and Using Data Storage Devices," p. 781;
"Using Disks and Discs," p. 227
Controls the display properties you use
"Finding, Installing, and Using a Monitor," p. 744
Controls how your Mac sleeps
"Managing Your Mobile Mac's Power," p. 982
Configures handwriting recognition
"Installing and Using an Ink Device," p. 731
Keyboard & Mouse
Sets keyboard and mouse preferences
"Finding, Installing, and Configuring a Keyboard," p. 722;
"Finding, Installing, and Configuring a Mouse," p. 728;
"Using and Configuring the Trackpad," p. 988
Print & Fax
Configures printer settings and fax services
"Finding, Installing, and Using Printers," p. 759;
"Working with Mac OS X's Built-in Fax Capability," p. 772
Manages your system sound and alert sounds
"Controlling Your System's Sound," p. 217
Internet & Network
Configures your .Mac account and enables you to work with your iDisk
"Using a .Mac iDisk and HomePage to Create and Serve Your Web Pages," p. 426;
"Working with Your iDisk," p. 228
Internet & Network
Configures your network settings for both Internet access and your LAN
Chapter 10, "Connecting Your Mac to the Internet," p. 263;
Chapter 26, "Building and Using a Network," p. 821
Internet & Network
Enables you to configure QuickTime for your Mac
"Configuring QuickTime," p. 648
Internet & Network
Controls access to your computer's services from the network and the Internet and enables you to configure Mac OS X's built-in firewall and set up Internet account sharing
"Using Mac OS X to Serve Web Pages," p. 446;
Chapter 26, "Building and Using a Network," p. 821;
"Defending Your Mac Against Net Hackers," p. 911;
"Using a Mac Running OS X to Share an Internet Account," p. 857
Creates, configures, and manages user accounts
"Creating User Accounts," p. 24
Controls your Classic environment
"Installing, Configuring, and Running the Classic Environment," p. 186
Date & Time
Manages the time and date settings and the clock for your system
"Changing the Clock Display," p. 121;
"Working with the Date and Time," p. 221
Maintains your system software
"Using Software Update to Maintain Your Software," p. 874
Manages speech recognition and Text-to-Speech
"Controlling Your Mac's Speech," p. 223
Selects the startup volume that is used the next time you start your Mac
"Choosing a Startup Volume with System Preferences," p. 228
Controls options to improve access for physically or mentally challenged users
"Using the Universal Access Pane to Make Your Mac More Accessible," p. 216
You might see more or fewer panes in the System Preferences application than are listed in Table 8.1 depending on the hardware and software you have installed. For example, if your Mac doesn't support Bluetooth hardware, you won't see the Bluetooth pane. If you have installed additional hardware or software that is configurable, such as a keyboard, you might see additional panes in the Other category.
Remember that you can customize the System Preferences application's toolbar by dragging icons from the lower pane of the window to the toolbar. You can remove icons from the toolbar by dragging them off the toolbar.
Use the Appearance pane of the System Preferences application to control several basic settings for your system.
Use the Appearance pop-up menu to select Blue if you want color in the buttons, menus, and windows. Select Graphite if you want to mute the color so the color elements are gray instead. Use the Highlight pop-up menu to select the highlight color.
Use the radio buttons to set scrolling behavior. You can place the scroll arrows together or choose to have a scroll arrow placed at each end of the scrollbar. You can select "Scroll to here" to cause a window to jump to the relative position on which you click or "Jump to next page" to scroll a page at a time when you click above or below the scroll box.
Set the number of recent items tracked on the Apple menu for applications and documents using the Number of Recent Items pop-up menus. You can track as few as none or as many as 50 recent items.
The lower part of the pane provides the controls you use to configure how font smoothing is enabled on your Mac. Font smoothing (known as antialiasing for graphics) reduces the jaggies that occur when you view certain fonts onscreen; this is most noticeable when you use larger sizes or thick fonts or when you apply bold or other formatting. Font smoothing is always turned on, but you can configure it specifically for your system:
Open the Appearance pane of the System Preferences application.
At the bottom of the pane, select the smoothing style you want to use on the "Font smoothing style" pop-up menu. Your options are Standard ? Best for CRT, Light, Medium ? best for Flat Panel, or Strong. You will probably be satisfied with the option appropriate for the display type you use, but you can experiment with the other options to see whether one of them matches your needs better.
Select the font size at or below which text smoothing is disabled on the "Turn off text smoothing for font sizes" pop-up menu. Because the effect of smoothing is less noticeable at small font sizes, your system can save some wasted processing power by not smoothing fonts displayed at small sizes. The default value is 8 points, but you might not even notice if you increase this value slightly.
Mac OS X includes support for a large number of languages; language behaviors; and date, time, and number formats. You control these properties through the International pane of the System Preferences application (see Figure 8.1).
Use the Language tab to configure the languages you want to use. The Languages list shows the languages that are currently active. You can drag these languages up and down in the list to set the preferred order in which you want to use them on menus and in dialog boxes. If you click the Edit button, you can choose the languages that appear in the Languages list by unchecking the check boxes for the languages you don't want to use. If you click the Customize Sorting button, you can choose the set of behaviors for each script. For example, to configure the Roman script for English, select it on the list of scripts and select the English option on the Behaviors pop-up menu. You can configure behaviors for other languages using similar steps to match the language you use.
Use the Formats tab to configure the format of the dates, times, and numbers used on your Mac. When you open this tab, you see a section for each of these areas along with the Region pop-up menu (see Figure 8.2).
Select the region setting for your Mac on the Region pop-up menu. By default, you see region choices that relate to the languages you have installed. If you want to see all possible region options, check the "Show all regions" check box. When you make a selection, default formats for the region you selected are applied to each setting area (dates, times, and numbers).
After you have set general format preferences via the Region pop-up menu, you can customize the format in each area.
The options described in the following paragraphs are for the United States region. If you choose a different region, different options might be available to you, but they can be set using similar steps.
In the Dates section, click the Customize button. The Customize Dates sheet appears. Use these controls to set the date formats displayed in Finder windows and other locations. There are two general date formats: Long Date and Short Date. Use the pop-up menus, check boxes, and text fields to set the format for each type of date. For the Long Date format, you choose a prefix as well as separators for the day of the week, month, day, and year. If you want to use a leading zero for single digit dates, check the "Leading zero for day" check box. For the Short Date format, you select the format option you want on the pop-up menu, input a separator, choose to use a leading zero for day or month, and choose to show the century. At the bottom of the sheet is an example of dates as you have configured them. Click OK to close the sheet.
In the Times section, click the Customize button. The Customize Times sheet appears. Use the radio buttons to select a 12- or 24-hour clock and whether noon and midnight are shown as 0:00 or 12:00. Use the Before Noon and After Noon boxes to select how your Mac indicates these relative times, such as AM or PM. Use the Separator box to input the separator you want to use. Finally, use the check box to determine whether a leading zero is used for the hour. Click OK when you are done making changes.
The settings you make in the Dates and Times sheets affect the format of these values in the Finder and other locations. They do not affect the clock display; you control the format of the clock using the Time & Date pane.
In the Numbers section, click the Customize button. The Customize Numbers sheet appears, which you can use to set the format for numbers displayed on your Mac. You can use the pop-up menus to select the separators in numbers (for the decimal and thousands), and you can select a currency symbol and where that currency symbol is located (before or after the amount). Click OK when you are done.
Use the Measurement Units pop-up menu to select the default measurement units used (U.S. [aka English] or Metric).
Use the Input Menu tab to control and configure the Input menu that appears on the menu bar.
To learn how to configure a keyboard for different languages, see "Configuring a Keyboard," p. 723.
To learn how to configure the Character Palette, see "Working with the Character Palette," p. 162.
Mac OS X was the first version of the Mac OS that included a built-in screen saver. Many Mac users enjoy having a screen saver, and Mac OS X's version provides the features you would expect. However, the quality and style with which the screen saver displays images are quite nice, especially when you use your own images.
Display Sleep Time
If you really want to protect your screen, use the Energy Saver pane to set a display sleep time. Display sleep actually turns off the display mechanism, which saves the screen. Of course, a blank screen isn't nearly as interesting as the screen saver. Using a screen saver with modern CRT displays isn't really necessary because they do not suffer the screen burn-in that earlier generations of such displays did.
Although LCD flat-panel monitors haven't been around long enough to be sure, some theorize that using display sleep is very important to maximize the working life of such displays. To be safe rather than sorry, you should keep the display sleep setting at a relatively low value if you use an LCD flat-panel display so it sleeps when you aren't actively using your Mac.
You use the Screen Saver tab of the Desktop & Screen Saver pane of the System Preferences application to configure a screen saver for your machine (see Figure 8.3).
You have three general choices: Use one of Mac OS X's default modules, use a module from images you have created or downloaded, or use a module that someone else has created and published via his .Mac account.
Using one of Mac OS X's built-in modules is straightforward. The general steps are the following:
Open the Screen Saver tab of the Desktop & Screen Saver pane.
If you want your Mac to randomly select and use a screen saver, check the "Use random screen saver" check box and skip to step 6.
Select the screen saver module you want to use from the Screen Savers list; you see a preview in the Preview window.
Use the Options button to set various parameters for the screen saver you select, such as whether a cross-fade is used between slides and whether slides are kept centered on the screen (not all modules have configuration options). The available display options are the following:
Cross-fade between slides? When enabled, one image fades into the next. If disabled, one image disappears before the next image appears.
Zoom back and forth? When enabled, the screen saver zooms in and out of each image.
Crop slides to fit screen? When enabled, images are sized so they fit onto the display by cropping the parts that don't fit.
Keep slides centered? When enabled, images are always centered on the screen.
Present slides in random order? When enabled, images appear in a random order rather than the order in which they are listed in the folder that contains them.
Test the screen saver by clicking the Test button. The images that are part of the screen saver are rendered and displayed with the configuration options you selected.
If you use multiple displays, a different image from the screen saver is shown on each display.
Use the "Start screen saver" slider to set the idle time that must pass before the screen saver is activated.
Click the Hot Corners button.
On the resulting sheet, select the corners to which you can move the mouse to manually start or disable the screen saver by selecting the action you want to occur on the pop-up menu located at the corner you want to configure. The default is to have no action occur at any corner.
If the display sleep time set on the Energy Saver pane is less than the time you set in step 6, you will never see the screen saver because the display will sleep before the screen saver is activated. If this is the case, a warning appears on the Energy Saver pane and a button enables you to jump to the Screen Saver tab. However, you don't see any warning on the Screen Saver tab. If you want to see a screen saver, check the display sleep setting on the Energy Saver pane to ensure that the display sleep time is greater than the screen saver activation time.
Some of the built-in modules are pretty cool (I especially like Cosmos), but you can have even more fun by creating or using a custom module. There are several ways to do this:
Gather the images you want to use for a screen saver in a folder and use the Choose Folder module to select that folder.
Create a screen saver from a collection of your own images by creating a photo album for that purpose in iPhoto. You can access any images in your iPhoto Photo Library as well as any of its photo albums on the Screen Savers list.
Use a screen saver that someone has made available through .Mac.
Use a screen saver you download from the Internet.
To create a screen saver from your own images, use the following steps:
Create a folder containing the images you want to use. The images can be in the standard image formats, such as JPG or TIFF.
To learn about creating images, see Chapter 15, "Creating and Editing Digital Images," p. 457.
Open the Screen Saver tab and select the Choose Folder module.
Use the Choose Folder sheet to move to and select the folder containing the images you want to use; then click Choose.
Use the other controls on the tab to configure the screen saver. You have the same display options as for the built-in screen savers.
You can choose to use the images within your Pictures folder by selecting it on the list of Screen Savers. Only the images located in the root folder (not within folders that are inside the Pictures folder) are used. You configure the screen saver using the same steps you use for other options.
Similarly, you can choose any images with your iPhoto Photo Library as a screen saver by selecting Photo Library. You can also select a photo album you have created in iPhoto as a screen saver by selecting it on the list that appears under the Photo Library on the screen saver list.
To learn how use iPhoto, see "Using iPhoto to Master Digital Images," p. 470.
Using the .Mac service, people can make their screen savers available to you and you can make your screen savers available to other people.
To learn how to use .Mac services, see "Using a .Mac iDisk and HomePage to Create and Serve Your Web Pages," p. 426.
To use a module available via .Mac, perform the following steps:
Open the Screen Saver tab and select the .Mac module. (A default .Mac module is available and is selected automatically.)
Click Options to see the Configuration sheet. The top of the sheet contains a list of .Mac screen savers to which you are subscribed. If the Selected check box is checked, the images in the screen saver are used. If not, they aren't used. You can see that you are already subscribed to the .Mac public slideshow.
Enter the .Mac member name of someone whose slideshow you would like to use as your screen saver in the .Mac Membership name field and press Return. The sheet closes.
Click Options again. The Configuration sheet appears. Now, the person whose .Mac name you entered in step 3 appears on the list of slideshows to which you are subscribed.
Repeat steps 3 and 4 to add more public slideshows to the list.
Check the Selected check box for each slideshow you want to be used in your screen saver. If the check box is unchecked, the slideshow is still available to you, but it isn't displayed. Because the .Mac screen saver displays all the images to which you are subscribed in the same screen saver, uncheck any screen savers whose images you don't want to be included.
To unsubscribe from a public slideshow, select the slideshow and press Delete. Of course, you can always just uncheck the box to prevent the images in that screen saver from being included. The difference is that if you unsubscribe, the images will no longer be downloaded to your Mac.
Use the Display Options check boxes to configure the screen saver. You have the same display options as for the built-in modules.
Configure and test the screen saver just like one of Mac OS X's built-in screen savers.
If you have people who are interested in you (such as relatives), you can create a .Mac public slideshow and inform those people who are interested that it is available. As you update your slideshow, people who subscribe to and use it see the images you add to the collection.
To learn how to publish a .Mac screen saver, see "Publishing Images As .Mac Slides," p. 508.
You can also download and use other screen savers from the Internet or other sources. Screen saver modules have the .saver filename extension. To do this, follow these steps:
Download the screen saver you want to use and prepare it for use.
For help with downloading and preparing files, see "Downloading and Preparing Files," p. 411.
Place the .saver file in the directory Mac OS X/Library/Screen Savers, where Mac OS X is the name of the startup volume.
Use the Screen Saver tab to choose and configure the screen saver you added.
You can use the Universal Access pane to make your Mac more accessible to those with various physical or mental challenges.
You configure special access to the system by using the Universal Access pane of the System Preferences application. This pane includes the following four tabs:
Seeing? Using the Seeing tab, you can configure the visual aspects of the system. You can use zoom to increase the size of items on the screen. You can also change the display to be white on a black background or grayscale. Use the "Enhance contrast" slider to increase the display contrast.
Hearing? The Hearing tab enables you to set the screen to flash when the alert sound plays.
Keyboard? Using the Keyboard tab, you can configure Sticky Keys that enable users to choose key combinations by typing only one key at a time. Click the Keyboard tab, and then use the radio button and check boxes to configure Sticky Keys. When Sticky Keys is on, each modifier keystroke is shown on the screen. For example, if you press the key, the key symbol appears onscreen. You can turn off this feature by unchecking the "Display pressed keys on screen" check box. You can also turn off the audible feedback by unchecking the "Beep when a modifier key is set" check box. You can enable Sticky Keys to be turned on or off from the keyboard by checking or unchecking the "Press the Shift key five times to turn Sticky Keys on or off" check box.
For people who have difficulty pressing and releasing keys, you can use the Slow Keys feature to set a delay for the time between when a key is pressed and when the input is accepted by the system. Use the Slow Keys radio button to enable or disable this feature. If enabled, use the slider and check box to configure it.
Mouse? The Mouse tab enables you to control the mouse by using the numeric pad on the keyboard. Click the Mouse tab of the Universal Access pane, and then click the On radio button to turn on Mouse Keys. Use the Initial Delay and Maximum Speed sliders to control how the pointer moves in relation to keystrokes. You can enable Mouse Keys to be turned on or off from the keyboard by checking or unchecking the "Press the option key five times to turn Sticky Keys on or off" check box.
The two check boxes at the bottom of the Universal Access pane enable you to configure general aspects of the universal access functionality. If you check the "Enable access for assistive devices" check box, you can control the system with specific assisting devices. If the "Enable text-to-speech for Universal Access preferences" check box is selected, the Mac speaks various options as you move the pointer over them.
You can click the ? button that appears on some panes to jump to specific topics in the Help system relating to the controls you are viewing.
You use the Sound pane of the System Preferences application to control the volume, sound effects, and input sources for your system (see Figure 8.4). The Sound pane has three tabs: Sound Effects, Output, and Input. You use the Sound Effects tab to configure your system alert sounds and various audio feedback. You use the Output tab to control the sound output of your Mac and use the Input tab to configure sound input devices attached to your Mac, such as USB microphones.
You can control your system's volume using the "Output volume" slider at the bottom of the pane. Use the Mute check box to mute all system sound. Check the "Show volume in menu bar" check box to show the Volume menu in the menu bar. You can control your main system volume by clicking this icon and using the pop-up slider to set the volume level.
If you use an Apple Pro keyboard, an iBook, or a PowerBook, you can also control the volume level using the mute and volume keys located just above the numeric keypad. When you press one of these keys, a sound level indicator appears onscreen so you can visually tell what the relative volume level is. (This also appears when you use another device to control the volume, such as a keyboard with a volume wheel.) You also hear the alert sound each time you press one of the volume keys. You can disable this audio feedback by unchecking the "Play feedback when volume keys are pressed" check box.
To configure your system alert sound, carry out the following steps:
Open the Sound pane of the System Preferences application.
Click the Sound Effects tab.
Select the alert sound you want to use on the list?you will hear a preview of the sound you select.
Select the output device through which you want the alert sound to be played on the "Play alerts and sound effects through" pop-up menu. If you have USB speakers installed, such as SoundSticks, you can choose to play alerts through them, or if you want to use your Mac's internal speaker, select Internal speakers.
Use the "Alert volume" slider to control the relative volume level of the alert sound.
If you have external USB speakers, it is usually a good idea to play the alert sound through the Mac's built-in speakers, especially if you like to listen to music or watch movies with high sound volume. This prevents the alert sound from knocking you out of your chair (if this has ever happened to you, you know exactly what I mean). If you set things this way, you probably need to set the alert volume high because the Mac's built-in speaker will be overwhelmed by your external speakers.
If you have analog speakers plugged in to the Mac's speaker jack, you won't be able to do this because the Mac's built-in audio controller controls the output to those speakers. You must be using USB speakers or those connected to another interface such as the digital audio port on a Power Mac G5.
Mac OS X can play various sound effects when you perform specific actions or when something specific happens (such as when you send an item to the Trash). This feature is enabled by default. To disable it, uncheck the "Play user interface sound effects" check box.
To configure the sound output for your system, use the following steps:
Open the Sound pane and click the Output tab. A list of all sound output devices attached to your machine appears; at the least, you see the Internal speakers option, which is your Mac built-in speaker or speakers, depending on which type of Mac you use.
Select the output device you want to configure. If output options are available for the selected output device, controls appear just under the list of available devices (see Figure 8.5).
Use the controls to configure the selected output sound source. For example, if you use a two-speaker system, use the Balance slider to set the relative volume balance between the speakers.
To configure sound input devices attached to your Mac, perform the following steps:
Attach the sound device you want to use. For example, to use a USB headset microphone, attach it to an available USB port.
Open the Sound pane of the System Preferences application and click the Input tab. You see a list of all input devices your Mac recognizes.
Select the device you want to configure.
Use the Input volume slider to configure the device's sensitivity. Dragging the slider to the right increases the level of sound through the device.
Test the device by speaking into it or making some other noise. The relative sound level appears on the Input level indicator.
Continue adjusting the device until you achieve the proper level of input.
Although these sound options satisfy most Mac users, there are more sound options you can choose to implement.
Under Mac OS X, system alert sounds are in the Audio Interchange File Format (AIFF). This is a good thing because you can use many sounds as your alert sound, and using QuickTime Pro, you can convert almost any sound into the AIFF format.
To learn how to convert sounds into the AIFF format using QuickTime Pro, see "Using QuickTime Pro to Convert Files into Other Formats," p. 672.
Under Mac OS X, AIFF files have the .aiff filename extension. By default, QuickTime Player Pro appends the .aif filename extension to files when you export them in the AIFF format. Be sure to add the second f to the filename extension for the sound you want to add as an alert sound. If you don't, the file will not be recognized as a valid alert sound.
There are two basic ways in which you can add alert sounds. You can add them to specific user accounts or to the system so they are accessible to everyone who uses your Mac.
To add an alert sound to a specific user account, perform the following steps:
Create or download the AIFF files you want to add to your available alert sounds.
Log in to the user account under which you want to make the alert sounds available.
Drag the new alert sounds to the following directory: /shortusername/Library/Sounds. The new alert sound is available to that user account on the Alert Sounds list in the Sound pane of the System Preferences application.
If the System Preferences application is open when you install a new alert sound, you must quit and restart it to see the new sound on the list.
When you install your own system alert sounds in the alert sound list, the type for the sounds you add is Custom instead of Built-in. Built-in sounds are stored in the Sound folder in the System Library folder instead of the user's Library folder.
You can also add alert sounds to the system so they are available to all the user accounts on your machine. However, to do this, you must log in under the root account.
You can't modify files or directories that are within the Mac OS X system directory without being logged in under the root account. Be careful when you are logged in under the root account because you can change anything on your system, including changing vital system files in such a way that your Mac fails to work. You can also delete any files on the machine while you are logged in as root.
To learn how to enable and log in under the root account, see "Logging In As Root," p. 236.
To add alert sounds to your system, do these steps:
Create or download the AIFF files you want to add to your alert sounds.
Log in under the root account.
Drag the AIFF file into the directory Mac OS X/System/Library/Sounds, where Mac OS X is the name of your Mac OS X startup volume.
Log out of the root account and then log back in under another account. The new sounds are available on the Alert Sounds list on the Sound pane of the System Preferences application.
The kind of alert sounds you add to the system are Built-in, just as the alert sounds that are preinstalled.
The Date & Time pane of the System Preferences application enables you to set and maintain your system's time and date (see Figure 8.6). You can set the time and date manually, or you can use a network timeserver to set and maintain your system's time and date for you.
To set your system's date and time, do the following:
Open the Date & Time pane of the System Preferences application.
Click the Time Zone tab and use the map to set your time zone. Drag the highlight bar over your location to select the correct time zone. Then, use the Closest City pop-up menu to select the specific time for the area in which you are located.
Click the Date & Time tab.
If you are going to use a network timeserver to maintain the time and date for your machine, check the "Set Date & Time automatically" check box and select the timeserver you want to use on the drop-down list. The options you see depend on where you are. There are three primary timeservers, one for the Americas, one for Asia, and one for Europe. Select the server that is appropriate for your location.
If you want to set the time and date manually, uncheck the "Set Date & Time automatically" check box. Use the straightforward controls to set the date and time.
Quit the System Preferences application.
To learn how to use the Clock tab to configure the desktop clock, see "Changing the Clock Display," p. 121.
You can find the official time for any time zone in the United States at www.time.gov. Of course, this is useful only if you live in the United States and can handle the time being off by as much as 0.3 seconds.
You can use the Speech pane of the System Preferences application to control two aspects of how your Mac uses speech (see Figure 8.7). Speech Recognition enables you to speak commands to your Mac; Spoken User Interface controls how your Mac reads the text in windows and dialog boxes or in documents from applications that speak text.
To configure speech recognition on your Mac, click the Speech Recognition tab and use the controls to configure how speech recognition works. On the On/Off tab, turn on speech recognition and then use the Listening tab to configure how your Mac listens to commands. Use the Commands tab to select the commands that are available when Speakable Items is turned on. Additional information about this feature is beyond the scope of this chapter. However, you might want to explore it to see whether it is useful to you.
To see which commands you can speak, turn on Speech Recognition. The feedback window appears after speech recognition is on. Click the arrow at the bottom of that window and select Open Speech Commands window. In the Speech Commands window is the list of commands you can speak. When you open an application that supports speech recognition, that application appears in the Speech Commands window and the list of spoken commands it supports is shown.
If you double-click the feedback window, it moves to the Dock.
If you use applications that support Text-to-Speech, those applications can read text to you. To configure the voice they use, open the Default Voice tab of the Speech pane of the System Preferences application. Select the voice from the Voice list and then set the rate at which the voice speaks using the slider. You can click the Play button to hear a sample.
Use the Spoken User Interface tab to configure spoken feedback from the system. You can use the Talking Alerts controls to configure specific phrases spoken to you and the voice used to speak those phrases. You can also choose to have a voice speak to you when any of the following events occurs:
An application requires your attention? With this feature enabled, when an application needs your attention, you hear an audible warning.
There is text under the mouse? You must be using an assistive device configured on the Universal Access pane to use this feature. When it's enabled, you hear the text under your pointer.
Text is selected and the key is pressed? When you enable this feature and press the key combination you select, your Mac reads to you any text you have selected.