Mac OSXでオーディオ出力を切り替えるApplescript

tell application "System Preferences"
    reveal anchor "output" of pane id "com.apple.preference.sound"
    activate    
    tell application "System Events"
        tell process "System Preferences"
            select (row 1 of table 1 of scroll area 1 of tab group 1 of window "サウンド" whose value of text field 1 is "内蔵スピーカー")
        end tell
    end tell
    quit
end tell