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Spectrums and spectrograms!

September 10, 2009

Hi everyone,

These are the links, spectrograms and spectral descriptions of my four sounds.

1. An A note playing on a classical guitar (link here)

The spectrum is set to linear bins and a window of 4096. The spectrum stays basically the same throughout the whole sound, with little variation in the frequencies. This makes sense because it’s one sustained note.

This is a spectrogram of the note playing on the classical guitar. The color is set to “Default,” the scale to “dBV^2,” the window to 1024, and the bins set to “Linear.”  I chose to do a dBV^2 spectrogram because it delineates all the different frequencies associated with this note — the fundamental frequency (which is at around 16Hz)  is the most prominent and visible frequency.

Almost everything else is black or green (indicating that the frequencies are not at a low volume). There is a pretty sharp attack at first, which is indicated by the red color of the fundamental frequency at the beginning of the sound and by numerous higher frequencies. However, as the sound sustains and eventually fades out, thehigher frequences go away and fundamental frequency fades from red to green, indicating that the volume is fading out.

2. A tennis rally on a hardcourt (link here)

Tennis rally spectrogram

In this spectrogram, the color is set to “Default,” the scale to “Linear,” the window to 8192, and the bins set to “Linear.”

With this spectrogram, all we can really gather from it is that there are a number of sharp attacks at certain intervals.  We can’t derive much about the harmonic characteristics of the sound because the many frequencies of the sound of hitting a tennis ball all blend into one blob. However, there is a certain range of frequencies that is always red and thus at a high volume.  Those frequencies are what make the distinct pitch of hitting a tennis ball with a racket.

3. Metal pieces clicking (link here)

Metal pieces spectrogram

In this spectrogram, the color is set to “Default,” the scale to “Linear,” the window to 1024, and the bins set to “Linear.”  I chose the Linear scale because it highlighted the fact that this sound contains mostly higher frequencies and also indicated the very quick, sharp and clean sounds of metal pieces clicking together.  As we can see from this spectrogram, the sound of metal clanking contains a bunch of frequencies across the board, which cannot be separated from each other very easily. The most we can perceive about the frequencies is that the majority of them are higher.

4. Tawny owls chirping (link here)

tawny owls spectrum

tawny owls spectrogram

The color is set to “Default,” the scale to “Linear,” the window to 1024, and the bins set to “Linear.”  The Linear scale was the one that most effectively indicated the fundamental frequency of the bird chirps.  As we can see from the arch-like shape of the frequencies, the chirps start off at a lower frequency, increase to a peak, and then return to that lower frequency.  The chirps have a distinct pitch, and that is also indicated by the red areas of the graph.

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One Comment leave one →
  1. September 13, 2009 6:01 pm

    The tennis rally sound is wrong no? It links to a pipe sound. It also looks strange to use a window size of 8192 samples, for this type of sound, it should be much shorter.

    Also for the metal piece the window size should be shorter, 256 or 512 should be good, since what we want is to preserve time resolution.

    The spectrogram of the owl could also be much clearer, zooming in time would allow to see the fundamental frequency, pitch, of the little melody.

    …xavier

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