function playback(nn,type,vv)

% PLAYBACK .... Playback sound files of different quantization levels.
%
%       PLAYBACK(N,TYPE) plays back the speech sound file which has
%               been quantized by an N-bit and TYPE quantizer.
%               Valid TYPE options are: 'uniform' and 'mu_law'.
%
%       PLAYBACK( N, TYPE, K) is the same but sets the output volume to
%               K where K is a positive integer between 0 and 100.
%               The default value used by PLAYBACK(X,TYPE) is 80.

%	AUTHORS : M. Zeytinoglu & N. W. Ma
%             Department of Electrical & Computer Engineering
%             Ryerson Polytechnic University
%             Toronto, Ontario, CANADA
%
%   DATE    : January 1992.
%   VERSION : 1.0

%===========================================================================
% Modifications history:
% ----------------------
%	o   Added "checking"  11.30.1992 MZ
%	o	Tested (and modified) under MATLAB 4.0/4.1 08.16.1993 MZ
%===========================================================================

global START_OK;
global BELL;
global WARNING;

check;

%--------------------------------------------------------------------------
%   Default values
%--------------------------------------------------------------------------
DEFAULT_VOLUME = 80;
NOPT = nan;

%--------------------------------------------------------------------------
%   Input parameter control
%--------------------------------------------------------------------------
if ((nargin ~= 1) & (nargin ~= 2)  & (nargin ~= 3))
        error(eval('eval(BELL),eval(WARNING),help playback'));
        return;
end
%---------------------------------------------------------------------------
%   Check validity of options
%---------------------------------------------------------------------------
if strcmp(type, 'uniform')
        NOPT = 0;
elseif strcmp(type, 'mu_law')
        NOPT = 1;
end
if isnan(NOPT), error('Unknown quantize TYPE'), end

if ( (nn > 8) | (nn < 1) )
        error('Only N-bit quantized sound files with 1 <= N <= 8 are available');
end

%--------------------------------------------------------------------------
%   Set parameters
%--------------------------------------------------------------------------
if( nargin == 2)
        volume = DEFAULT_VOLUME;
else
        if( (vv > 100) | (vv < 0) )
                error('Volume level must be between 0 and 100');
                return;
        end
        volume = vv;
end

if (NOPT == 0)                                  % uniform
        com = sprintf( ...
     '!play -v%3.0f /usr/local/matlab/toolbox/etc/sounds/speech_q%1.0f.au', ...
      volume, nn);
elseif (NOPT == 1)                              % mu-law
        com = sprintf( ...
     '!play -v%3.0f /usr/local/matlab/toolbox/etc/sounds/speech_mq%1.0f.au', ...
      volume, nn);
end

%--------------------------------------------------------------------------
%   Play bck the sound file
%--------------------------------------------------------------------------
eval( com );