Just have the Play button call a function you write called PlayNextSoundFile(). Then for the other 3 button callbacks, you do
function btnGood_Callback(hObject, eventdata, handles)
% Log score for this song.
songNumber = handles.songNumber; % Increment this in PlayNextSoundFile
handles.songScore(songNumber) = 2; % or whatever.
% Play the next sound file. Also increments handles.songNumber.
PlayNextSoundFile(handles);
guidata(handles);
Same thing for the okay and poor callbacks. Set the score to whatever number you want to use to rate them good, poor, or okay. Or alternatively you could put up a slider or a bunch of radio buttons to get the user's rating of that song.
