Error using extract Expected audioIn to be one of these types: single, double Instead its type was cell. Error in audioFeatu​reExtracto​r/extract (line 626) valid

% data store

ADS = audioDatastore('D:\sridhar\reference paper\data','FileExtensions','.wav','IncludeSubfolders',true);
data1 = readall(ADS);
Fs=48000;


% seperating the digits

zero={};
one={};
two={};
three={};
four={};
five={};
six={};
seven={}; 
eight={};
nine={};
for i=1:500
    if(i<=50)
        zero= [zero (data1{i,1})];
    elseif(i>50 && i<=100)
        one=[one (data1{i,1})]
    elseif(i>100 && i<=150)
        two =[two (data1{i,1})] 
    elseif(i>150 && i<=200)
        three =[three (data1{i,1})] 
    elseif(i>200 && i<=250)
        four =[four (data1{i,1})] 
    elseif(i>250 && i<=300)
        five =[five (data1{i,1})] 
    elseif(i>300 && i<=350)
        six =[six (data1{i,1})]
    elseif(i>350 && i<=400)
        seven =[seven (data1{i,1})]
    elseif(i>400 && i<=450)
        eight =[eight (data1{i,1})]
    elseif(i>450 && i<=500)
        nine =[nine (data1{i,1})]
    end
end


% labeling the digits

zeroLabels = repelem(categorical("zero"),1,50);
oneLabels = repelem(categorical("one"),1,50);
twoLabels = repelem(categorical("two"),1,50);
threeLabels = repelem(categorical("three"),1,50);
fourLabels = repelem(categorical("four"),1,50);
fiveLabels = repelem(categorical("five"),1,50);
sixLabels = repelem(categorical("six"),1,50);
sevenLabels = repelem(categorical("seven"),1,50);
eightLabels = repelem(categorical("eight"),1,50);
nineLabels = repelem(categorical("nine"),1,50);



% audio training data 
audioTrain = [zero(1:40),one(1:40),two(1:40),three(1:40),four(1:40),five(1:40),six(1:40),seven(1:40),eight(1:40),nine(1:40)];
labelsTrain = [zeroLabels(1:40),oneLabels(1:40),twoLabels(1:40),threeLabels(1:40),fourLabels(1:40),fiveLabels(1:40),sixLabels(1:40),sevenLabels(1:40),eightLabels(1:40),nineLabels(1:40)];


% validation data
audioValidation = [zero(41:end),one(41:end),two(41:end),three(41:end),four(41:end),five(41:end),six(41:end),seven(41:end),eight(41:end),nine(41:end)];
labelsValidation =[zeroLabels(41:end),oneLabels(41:end),twoLabels(41:end),threeLabels(41:end),fourLabels(41:end),fiveLabels(41:end),sixLabels(41:end),sevenLabels(41:end),eightLabels(41:end),nineLabels(41:end)];
% aFE = audioFeatureExtractor("SampleRate",Fs, ...
%     "SpectralDescriptorInput","melSpectrum", ...
%     "spectralCentroid",false, ...
%     "spectralSlope",true, ...
%     "mfcc",true);
featuresTrain = extract(aFE,audioTrain);
[numHopsPerSequence,numFeatures,numSignals] = size(featuresTrain)

Answer 1

[Suraj Kumar]

Hi @SRIDHAR C,

The error message you're encountering indicates that the extract function is expecting the input audioIn to be of type single or double, but it's being passed a cell array instead.

Here's how you can address this issue:

1.You can convert cell arrays to matrices if they are of the same length.

2. Alternatively, you can iterate over each signal to process them individually.You can refer to the following code snippet for better understanding:

aFE = audioFeatureExtractor("SampleRate",Fs, ...
    "SpectralDescriptorInput","melSpectrum", ...
    "spectralCentroid",false, ...
    "spectralSlope",true, ...
    "mfcc",true);
featuresTrain = cell(1, length(audioTrain));
for i = 1:length(audioTrain)
    audioSignal = audioTrain{i};
    audioSignal = double(audioSignal);
    featuresTrain{i} = extract(aFE, audioSignal);
end

Happy Coding!