function [Ptm_above_ATH, Pnm_above_ATH]= check_maskers(Ptm, Pnm, ATH, b)
% [important_tone_maskers, = check_maskers(power_spectral_density_tones,
%  important_noise_maskers]                power_spectral_density_noise,
%                                          absolute_threshold_of_hearing,
%                                          bark_array)
%
% check_maskers takes a masker power spectrum and checks to see if values
% are above the absolute threshold of hearing (ATH).  If not, the masker is
% eliminated because you will not hear it anyway. Then, it locates maskers
% that have other maskers within their critical bandwidth.  If one is
% found, the lower of the two is set to zero, because they will not be
% detectable by the human ear anyway.

% First, take the power spectrum.  If any of the values are below corresponding values
% of the absolute threshold of hearing, then set them to zero.  This is because
% it will not be heard anyway!
Ptm_above_ATH=Ptm.*(Ptm>ATH);
Pnm_above_ATH=Pnm.*(Pnm>ATH);

%figure;
%subplot(2,1,1);
%stem(b, Ptm_above_ATH);
%hold on;
%plot(b,ATH,'r--');
%xlabel('Frequency (Bark)');
%ylabel('Magnitude');
%title('Ptm above ATH');

%subplot(2,1,2);
%stem(b, Pnm_above_ATH);
%hold on;
%plot(b,ATH,'r--');
%xlabel('Frequency (Bark)');
%ylabel('Magnitude');
%title('Pnm above ATH');

% the remaining maskers must now be checked to see if any are
% within a critical bandwidth.  If they are, then only the strongest
% one matters.  The other can be set to zero.
% go through masker list
for j=1:length(ATH),
   toneFound=0;
   noiseFound=0;
   
   % was a tone or noise masker found?
   if (Ptm_above_ATH(j)>0)
      toneFound=1;
      %disp([num2str(j),' is a tone.']);   
   end
   if (Pnm_above_ATH(j)>0)
      noiseFound=1;
      %disp([num2str(j),' is noise.']);
   end
   
   % if either masker found
   if (toneFound | noiseFound)
      masker_loc_barks = b(j);
      % determine low and high thresholds of critical bandwidth
      crit_bw_low  = masker_loc_barks-0.5;
      crit_bw_high = masker_loc_barks+0.5;
      % determine what indices these values correspond to
      low_loc  = max(find(b<crit_bw_low));
      if (isempty(low_loc))
         low_loc=1;
      else
         low_loc=low_loc+1;
      end
      high_loc = max(find(b<crit_bw_high));
      
      % at this point, we know the location of a masker and its
      % critical bandwidth.  Depending on which type of masker it is,
      % go through and eliminate maskers within the critical bandwidth that
      % are lower.
      % go through critical bandwidth
      for k=low_loc:high_loc,
      		if (toneFound)
				% find other tone maskers in critical bandwidth
				if ((Ptm_above_ATH(j) < Ptm_above_ATH(k)) & (k ~= j)),
					Ptm_above_ATH(j)=0;
					%disp(['Ptm(', num2str(j),') < Ptm(', num2str(k),')']);
					break;
				elseif (k ~= j)	
					Ptm_above_ATH(k)=0;
				end
				% find noise maskers in critical bandwidth
				if (Ptm_above_ATH(j) < Pnm_above_ATH(k)),
					Ptm_above_ATH(j)=0;
					%disp(['Ptm(', num2str(j),') < Pnm(', num2str(k),')']);
					break;
				else
					Pnm_above_ATH(k)=0;
				end
			elseif (noiseFound)
				% find other noise maskers in critical bandwidth
				if ((Pnm_above_ATH(j) < Pnm_above_ATH(k)) & (k ~= j)),
					Pnm_above_ATH(j)=0;
					disp(['Pnm(', num2str(j),') < Pnm(', num2str(k),')']);
					break;
				elseif (k ~= j)	
					Pnm_above_ATH(k)=0;
				end
				% find tone maskers in critical bandwidth
				if (Pnm_above_ATH(j) < Ptm_above_ATH(k)),
					Pnm_above_ATH(j)=0;
					%disp(['Pnm(', num2str(j),') < Ptm(', num2str(k),')']);
					break;
				else
					Ptm_above_ATH(k)=0;
				end
			else
				disp('ERROR??');
			end
		end
	end
end