These clicking sounds appear to be related to the interaction between the version of Sound Manager that is installed with System 7.5 Update 2.0 and the sound chip in some Power Macintosh and Macintosh Performa 5200 series computers. The computers that may be affected have 8-bit, 22.254 sound output. To determine whether your computer has 8-bit sound follow these steps:
1. Choose Control Panels from your Apple menu.
2. Open the Sound control panel.
3. Choose "Sound Out" from the "Alert Sounds" pull down menu. If the 16-bit sound input radio button is grayed out, you have 8-bit sound.
4. Use the close box in the upper left corner to close the Sound control panel.
System 7.5.1, which was included on your computer, has Sound Manager version 3.0.2 built into it. After updating with System 7.5 Update 2.0, Sound Manager 3.2 is installed. The clicking sound occurs only on Power Macintosh and Performa 5200 series computers which have 8-bit sound and which have Sound Manager 3.2 installed.
To resolve this issue, you should install QuickTime 2.5, which installs Sound Manager 3.2.1. After upgrading the Sound Manager to 3.2.1, the clicking sound no longer occurs in the Sound control panel.
QuickTime software can be found at:
http://www.apple.com/quicktime/
This article was published in the Information Alley on 27 September 1996.