Problem translating sound file to spectrogram

I made a simple neural network with a few words. Converted to a microcontroller. All OK. I convert a file with one of the words into a spectrogram with the tools that come with TensorFlow. Sew in the code, everything is fine, the neural network recognizes the word. Using the code to convert an audio file into a spectrogram from Tensorflow light for MCU, I wrote my library (in C). But the appearance of the spectrograms is different. What is the problem? If need, i can show the code.

The top graph is the work of my library.

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