make figure spectrogram as length as signal above it

I would like to put spectogram result below the signal figure. I use specgram (in second row) and spectogram result in last row, but i get difficulties to make the lenght of spectogram, figure as length as signal figure. Can somebody help me?

[Mann Baidi]

"i get difficulties to make the lenght of spectogram, figure as length as signal figure."

Do you mean the dimensions of the figure or the values of the x-axis (time values)?

[Mathieu NOE]

yes , having the colorbar in one only subplot will destroy the x axis alignment

there are certainly many answers to the same question, one "old fashioned" way was described here already long time ago :

plot - Matlab: How to align the axes of subplots when one of them contains a colorbar? - Stack Overflow

[Mathieu NOE]

more recent :

subplot aligment automatic method - MATLAB Answers - MATLAB Central (mathworks.com)