Panasonic CF-28 series Operating Instructions Manual page 31

Microphone Jack
External Keyboard/Mouse Port
USB Port
NOTE
About the Problem of “Howling”;
The problem of "howling" sometimes occurs when a hand approaches the microphone.
In such cases, do the following.
1
2
3
Or, to prevent this problem, adjust the microphone volume and speaker volume to moderate levels.
Hard Disk Drive
<Attaching the strap>
1
3
2
4
External Display Port
Parallel Port
Serial Port
Expansion Bus Connector
Headphone Jack
MP Release Lever
Battery Pack
CAUTION
31