How to add my voice samples to validation.txt and testing.txt? Speech recognition

Hi im trying to do my own project with matlab basic on this example:https://www.mathworks.com/help/deeplearning/examples/deep-learning-speech-recognition.html

i dont know how to divide my own samples to validation.txt and testing.txt just write it?

When i try write it by myself in part Split Data into Training, Validation, and Test Sets, when i try in matlab this :

XTrain = speechSpectrograms(adsTrain,segmentDuration,frameDuration,hopDuration,numBands);

XTrain = log10(XTrain + epsil);

XValidation = speechSpectrograms(adsValidation,segmentDuration,frameDuration,hopDuration,numBands);

XValidation = log10(XValidation + epsil);

XTest = speechSpectrograms(adsTest,segmentDuration,frameDuration,hopDuration,numBands);

XTest = log10(XTest + epsil);

YTrain = adsTrain.Labels;

YValidation = adsValidation.Labels;

YTest = adsTest.Labels;

it gives me error :

Index in position 2 is invalid. Array indices must be positive integers

or logical values.

Error in speechSpectrograms (line 43)

X(:,ind,1,i) = spec;

I dont know how to fix it, my own data set is 14 wav files : MONO 16000Hz 16 bits PCM Windows created by using Audacity 2.2.2

Matlab 2019

it is that because I divide all 14 wav files in this two txt files?

when i try to write only 5 wav files do each txt files it gives me the same error and 4 were not saved anywhere i wantem them to go to training but i dont know how to split them to this to txt files.

Do i have to ender this wav's manually or divide using matlab or something? in this example theres no anwser how to split them.