[ubuntu] Changing default sound "voice" of laptop

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http://ubuntuforums.org – I'm running 12.04 on a Toshiba Satellite A30, and have numerous music software programs installed from my abortive attempt to connect a midi keyboard, and found most pretty confusing for my old brain to set up. I'm now using both nted and MuseScore to generate scores for my hammer dulcimer. During playback of my attempts at composition, the default sound that the onboard device produces is the familiar characterless "beep". (I admit I haven't yet explored the voicing possibilities within MuseScore, but I'm looking for something that would work at a more basic level across the who (Hardware)