The SoundSentryProc function is an application-specific callback function that produces a customized visual signal when the SoundSentry accessibility feature is on and a Win32-based application (or an application running in a window) generates a sound through the computer's built-in speaker.

  DWORD dwMillisec,  // duration of visual signal
  DWORD fdwEffect    // effect-type flag


Specifies the duration, in milliseconds, of the visual signal that is displayed when a Win32-based application (or an application running in a window) generates a sound.
Specifies the type of visual signal to display. Currently, this value must always be SSWF_CUSTOM.

Return Values

If the visual signal was or will be displayed correctly, the return value is TRUE. If the signal is asynchronous and the status is not available when the function is called, it should return TRUE.

If an error prevented the signal from being displayed, the return value is FALSE. To get extended error information, call GetLastError.


The SoundSentryProc function must be defined in a 32-bit DLL, and the DLL must export a function with the name SoundSentryProc.

The SoundSentryProc function is called only after an application or library calls the SystemParametersInfo function, specifying the SPI_SETSOUNDSENTRY value and the address of a SOUNDSENTRY structure whose iWindowsEffect member is set to SSWF_CUSTOM.


  Windows NT/2000/XP: Included in Windows NT 3.1 or later.
  Windows 95/98/Me: Included in Windows 95 or later.
  Header: Declared in Winuser.h; include Windows.h.

See Also

Accessibility Functions, SOUNDSENTRY, SystemParametersInfo

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