[ubuntu] Webcam works on Acer Aspire 5738 but no sound

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http://ubuntuforums.org – Just installed Ubuntu 9.10 on my new laptop. Everything seems to work well, the touchpad seems a little unresponsive when it come to tap clicking but, overall OK. the only piece of hardware that has failed to function totally is the built in mic. I've installed 'Cheese' and the webcam works ok but no sound. Sound preference dialog shows microphone1 and microphone2 but there is no input (or output) from either. Any ideas? (Hardware)