Vertical lines noise in spectrogram I have started looking into DSP and made an implementation of short-time fourier transform, using kissFFT to perform the FFT. I then render a spectrogram.

An example image that I have generated can be seen below. On top is the spectrogram of a music file from my implementation and under it is the spectrogram of the same section generated from audacity.



My concern is the vertical lines that show up from my implementation, which are most visible in the higher frequencies. They may interfere with other stuff I will try to do later on. Has anyone ever had the same problem or know the cause? How can I get rid of them?

Additional information:
I use hamming window with 50% overlap (using different windows has not helped)
After wasting forever on this problem, I found that it was just a question of window function. Doh!

Window functions that are not zero-ended produce these vertical lines. For example, Rectangular Window, Hamming Window, Gaussian Window (with low sigma) produce these lines, and Barlett Window, Hanning Window, Blackmann Window, Welch Window, don't.

I had tried other window functions but maybe during my tests, I made a coding mistake so I didn't find the fix. Moral of the story : do tests carefully!