It is possible to change keyword click volume on Android 4.3 However, this feature is currently disabled on mobile phones. This posts tells you how to change keyboard click volume in Nexus 7 2013 model.
How to Change the Keyboard Click Volume in Nexus 7
- With the Google Keyboard open, long press on the microphone icon until the settings button appears, then release.
- Tap “Google Keyboard Settings.” (From here you can completely disable audio feedback for the keyboard by unchecking “Sound on key press.”)
- Scroll down and tap “Advanced settings.”
- Tap “Keypress sound volume” and use the slider to set the level to your preference.
As said, this feature is not available on Phones with Nexus 4.3 yet. The option itself is listed in the Advanced Settings menu, but it is disabled. I used a Nexus 4 to test this.
via Android Central.