matlab starting audio

I am trying to display audio at real time using, analoginput, this is the code:

function Cspe()

        daq_object = analoginput('winsound');
        chan = addchannel(daq_object,1);
        num_samples=1000;

        set(daq_object,'SamplesPerTrigger',inf,'SamplesAcquiredFcnCount',num_samples,...
           'SamplesAcquiredFcn',{@up,num_samples});

    if(strcmp(daq_object.running,'On'))
        return;
    else
        start(daq_object);
    end

    end

    function up(num_samples)
    data=getdata(daq_object,num_samples);
    a=[1:num_samples];
    plot(a,data);

    end

but it keeps on giving me errors saying Winsound is already in use. i am not so sure what the problem is?, i made sure that if the device is on/running, don't do anything.