Overtone

Overtone is a Windows application for physics courses, designed to make experiments and demonstrations in the fields of acoustics, oscillations and musical instruments.

Overtone does not work under 64-bit Windows. But you may install a virtual Windows 32 system using any of the well-known virtual systems like:

  • Windows Virtual PC that emulates XP. Free download from the Microsoft site.
  • VMware Player. Free download from VMware site
  • Oracle VirtualBox. Free download from VirtualBox site

Examples
In synthesizer experiments you select the amplitudes and phases of the fundamental and 9 overtones to construct the beginning of a Fourier series. The sum is seen on a graphics display and the signal is available as sound card output.

You can test the Helmholtz assumption that the relative phases of the overtones are irrelevant to hearing.

In analyser experiments you capture sound from the sound card or from a WAV file up to several seconds long, select the starting time of the time slice and analyse time and frequency responses. The example shows the spectrum of a piano playing a middle C (262 Hz). The non-harmonic overtones are clearly seen. (Due to the stiffness of the string, the frequencies of the partials are too high.)

You may filter data with a digital filter and display spectrograms in color mode. This example shows the spectrogram taken from the word "harris" in the frequency range 0..10 kHz with a 4096-point-FFT every 2 ms (post processing). The formants of "i" and the high spectral components of "s" are clearly visible.
Sonogram
Short time spectral information may also be displayed in a 3-D representation, called "waterfall". The following example shows the waterfall spectrum of the same word "harris" as before. The red layer picks out the spectrum of "i" where the formants are visible again. The presentation may be rotated automatically or manually with scroll bars, in order to select the best "camera point".
 

 

Download version 1.15, June 2009: OVERTONE.ZIP (1.55 MB)

Unpack in a new folder, read README.TXT and start OVERTONE.EXE
(Some firewalls or User Access Control (UAC) may block execution. Give OVERTONE the necessary permissions.
Make sure, that the sound device is not used by another application.)

For more information, send e-mail to address given in README.TXT

Unterrichtseinheit Analyse von Klangspektren von Alain Hauser (in German)

 
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