Muhammad - you can either extract the data from the plot (from handles.axes1) or just save the recorded data to the handles object in the first push button callback. Try
function pushbutton1_Callback(hObject, eventdata, handles)
% your code from above
% save to the handles object
handles.myrec1 = myrec1
guidata(hObject, handles); % <--- You need this to save the updated handles structure
Your second callback would look something like
function pushbutton1_Callback(hObject, eventdata, handles)
if isfield(handles, 'myrec1')
% compress the data
audioData = handles.myrec1;
% plot
end
