Sound

You can incorporate sound as a part of an application in several ways — for example, music, speech, or sound effects. Such auditory information can take the following forms:

• A primary form of information, such as the composition of a particular piece of music or a voice message.
• An enhancement of the presentation of information that is not required for the operation of the software.
• A notification or alerting of users to a particular condition.

Sound can be an effective form of information and interface enhancement when appropriately used. However, avoid using sound as the only means of conveying information. Some users may be hard-of-hearing or deaf. Others may work in a noisy environment or in a setting that requires that they disable sound or maintain it at a low volume. In addition, like color, sound is a very subjective part of the interface.

As a result, sound is best incorporated as a redundant or secondary form of information, or supplemented with alternative forms of communication. For example, if a user turns off the sound, consider flashing the window's title bar, taskbar button, presenting a message box, or other means of bringing the user's attention to a particular situation. Even when sound is the primary form of information, you can supplement the audio portion by providing visual representation of the information that might otherwise be presented as audio output, such as captioning or animation.

Note
The taskbar can also provide visual status or notification information. For more information about using the taskbar for this purpose, see Chapter 10, "Integrating with the System."

Always allow the user to customize sound support. Support the standard system interfaces for controlling volume and associating particular sounds with application-specific sound events. You can also register your own sound events for your application.

The system provides a global system setting, ShowSounds. The setting indicates that the user wants a visual representation of audio information. Your software should query the status of this setting and provide captioning for the output of any speech or sounds. Captioning should provide as much information visually as is provided in the audible format. It is not necessary to caption ornamental sounds that do not convey useful information.

Note
The GetSystemMetrics function provides access to the ShowSounds and SoundSentry settings. For more information about this function and the settings, see the documentation included in the Microsoft Win32 Software Development Kit (SDK).

Do not confuse ShowSounds with the system's SoundSentry option. When the user sets the SoundSentry option, the system automatically supplies a visual indication whenever a sound is produced. Avoid relying on SoundSentry alone if the ShowSounds option is set because SoundSentry only provides rudimentary visual indications, such as flashing of the display or screen border, and it cannot convey the meaning of the sound to the user. The system provides SoundSentry primarily for applications that do not provide support for ShowSounds. The user sets either of these options with the Microsoft Windows Accessibility Options.

Note
In Microsoft Windows 95, SoundSentry only works for audio output directed through the internal PC speaker.