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Jesse’s Spectral Analysis

September 9, 2009

1.  Trumpet

Jesse - Trumpet Spectrum
Trumpet Spectrum

frequency analysis,trumpet,spectrogram
Trumpet Spectrogram

I took a short sampling from the sound linked above where the trumpet is playing the first sustained note.  As expected, the spectrum has peaks at multiples of the fundamental frequency, which is the first high peak observed.  I calculated the spectrum at a point in time where the trumpet is holding a note steady, so the peaks are clear.  The spectrogram of the sound shows that the trumpet has significant contributions from about the first 10 harmonics, and then lesser contributions for up to 18 or 20 harmonic frequencies. It’s interesting that at the end of the note the lower harmonics are still present but the upper frequencies die out the quickest.

2.  Wood Mill (Hammering)

spectrum,frequency analysis,hammer,hammering
Hammering Spectrum

spectrogram,frequency analysis,hammer,hammering
Hammering Spectrogram

For this sharp hammering sound, I calculated the spectrum close to the impact.  Both the spectrum and spectrogram show a large range of frequencies, and there does not appear to be any dominant fundamental frequency.  This agrees with our perception of the sound as well: it sounds like a noise without any pitch.  The spectrogram shows that a full range of low to high frequencies are present at the initial impact, and the higher frequencies appear to die out the quickest. There are a few broad frequency bands that may repeat.

3.  Clang (metal tray being hit)

Jesse - Clang Spectrum
Clang Spectrum

Jesse - Clang Spectrogram
Clang Spectrogram

The spectrum of the clanging sound was calculated close to the initial impact.  It shows that the sound is a combination of many different frequencies, although there are many clear peaks.  The spectrogram shows that at the initial impact, there are several fundamental frequencies contributing to the sound that die out at different rates.  Towards the end of the time course there appear to be two fundamental frequencies that sustain and create the ringing sound that we hear.

4. Nightingale

Jesse - Nightingale Spectrum
Nightingale Spectrum

nightingale,song,bird call,bird,spectrogram,frequency analysis
Nightingale Spectrogram

The spectrum from this selection from a nightingale song consists of just one frequency, with faint phantom harmonics visible in the spectrogram. The spectrum image shown is from a timepoint in the middle of one of the bird’s notes, where the note is the most stable.  The spectrogram is adjusted to highlight the difference in intensity between the fundamental frequency and the phantom harmonic.


One Comment leave one →
  1. September 13, 2009 5:28 pm

    Excellent descriptions and plots. The only comment is about the clang sound. It does not have several fundamental frequencies, it has none. It has has many frequencies, partials, but since there is no periodic relationship we do not hear a pitch.


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