Hi Simon,
Here's a quick and dirty to spectrogram:
There are three dimensions you are interested in for sound:
1) frequency
2) intensity (volume/amplitude)
3) time
Waveform view (what you are used to) only represents time and intensity (you
can glean some frequency info if you are an expert but don't count on it).
Spectrograms provide information about all 3 dimensions.
* Left to right is the time scale, just like waveform view.
* Up and down is the freuqency scale -- this is not what you are accustomed to.
Generally you will see a lot of horizontal lines in a spectrogram. The higher
the point in the spectrogram, the higher the pitch.
* Color represents intensity. The colors used are different for each program
but usually you will see a scale in the spectrogram window, or just figure it
out intuitively by playing a note and checking out what color the lines are;
usually it's pretty self explanatory, like the colors in a topographic map.
SO.. speaking of playing a note or two:
Record yourself playing a note, or even better, a scale.
Then create a spectrogram of the audio. You will see a bunch of ascending
lines. A vertical group corresponds to a single note. Remember that your horn
does not produce a single frequency but a group of frequencies including the
fundamental.
Look at the relative amplitudes. The fundamental is at the bottom. Is it the
strongest? What is your strongest harmonic? This tells you a lot about tone.
Look at what goes on between the notes. Is there crud?
Look at the horizontality of the lines -- are they steady or does your pitch
waver? Does it sag at the end of the note, or go sharp?
I have put up a sample spectrogram of me humming C2,D2,E2,F2,G2,C3 at:
http://gelfo.net/dg/spec.jpg
See on the first note, my 2nd harmonic is stronger than my first. On the
second, the fundamental is strongest. Note that in general my pitch is
unsteady (although the 3rd note seems pretty steady). You can tell that my
humming tone is not very full because there are missing harmonics towards the
top of the spectrum.
When I went from G2 to C3, it was very messy, you can see a bit of a mess in
between those notes. A good slur would NOT look like that; the notes would be
connected but it would be a smooth, quick transition. Jagged slurs are bad
slurs!
Hope this helps. Let me know if you have any questions.
Regards,
Marc Gelfo
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