MATLAB: How to convert Normalized frequency back to Frequency on the graph

normalized frequencyspectrogram

Dear All,
I need to change the Y-axis unit on this graph back to frequency[HZ], I'd really appreciate your answers.
Thank you in advance.

Best Answer

I should have set the frequency range to solve this problem.
spectrogram(x,window,noverlapp,nfft,'yaxis',frequency range);