makeasound.m

基于MATLAB的声音跟踪系统演示

function makeasound(varargin)
%MAKEASOUND Make a sound.
% MAKEASOUND will create an analogoutput object and continuously play a 
% 1000 Hz sine wave through the object. MAKASOUND STOP will stop
% the object from playing the sound.
%
% MAKASOUND(fo) will play a sine wave at fo Hz
% MAKEASOUND(wavefile) will use the data stored in wavefile.

% See also CONFIGUREWHEREISIT, WHREISIT, GETMAGNITUDE.

if nargin,
    % Check to see if called as MAKEASOUND STOP
    if strcmp(lower(varargin{1}),'stop'),
        % If being told to stop, find the object playing the sound and stop it.
        Objects=daqfind('Name','Produce Sound');
        for lp=1:length(Objects),
            stop(Objects{lp});
            delete(Objects{lp});
        end
        return;
        fo=1000;      %Default frequency
    elseif findstr(lower(varargin{1}),'.wav')
        %Specify a .wav file for source of sound    
        filename = varargin{1};
        
    else,     %Specify frequency
        fo = varargin{1};
    end % if strcmp
else
    fo=1000;      %Default frequency
    
end % if nargin

% Create the analogoutput with two channels
%(If use one channel, will create mono signal)
AO=analogoutput('winsound');
addchannel(AO,1:2);

AO.SampleRate=44100; % Hz
AO.RepeatOutput=inf; % Run forever
AO.Name='Produce Sound'; % Name the object

if exist('filename','var') & exist(filename,'file')
    [y,fs] = wavread(filename);
    y=y(:,1);           %Require mono signal
    AO.SampleRate=fs; % Hz
else
    % Create the sine wave
    t=(0:1/AO.Samplerate:1-1/AO.SampleRate)';
    y=2*sin(2*pi*fo*t);
end;

% Put the data into the object and start the object.
putdata(AO,[zeros(size(y)) y]);     %Send data to right speaker only
start(AO);

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