Timbre

Timbre is an application that shows the musician what a sound looks like in a way that makes sense musically. You can see what the tones of different instruments sound like, or differences in your own tone. You can see why some tones sound harmonious and others don’t. You can see when people are not playing together in tune.

The sound of most musical instruments is made up of air pressure vibrations at the frequency of the note being played. This is usually called the fundamental frequency.

However, because instruments are in the real world, physics gets involved and this vibration resonates with the instrument itself, or in the pipe or cavities of the instrument, producing extra vibrations at multiples of this fundamental frequency. The slight differences in the strengths and frequency (some instruments higher harmonics are not exactly multiples) are what makes each instrument sound the way it does.

A common way of looking at these components of sound is by looking at the spectrum of the sound. You may have seen pictures like this one, that show these harmonics.

However, this is only really interesting if you like physics and mathematics. It isn’t easy to see how this relates to music.

So how can we make this very mathematical representation more musically meaningful? By adding knowledge of how human ears work. The first key, is that we hear frequencies on a different scale (logarithmic). This is why each octave difference in note equals a doubling of frequency. The other key aspect is that we hear sound levels on a logarithmic scale as well. Putting this information on the spectrum is an improvement, but it still isn’t easy to to see how to apply this to music.

Timbre shows this spectrum, wrapped around a circle so that each revolution around the circle is an octave. The circle has the 12 semitones of each octave marked on the circle and suddenly we can see that a single note has frequency components at precise notes (5th, 3rd).

There’s some tricky processing going on behind the scenes to solve some arcane signal processing issues to get this working nicely, but the result is that each timbre has a different pattern of spikes that rotates with pitch.

This way of looking at sound can help explain why certain intervals sound nice together (the spikes line up). You can even get two people to play at the same time to see the spikes line up properly and hear the result.

There are many other ways that this view of sound can be used. Please me any interesting ones that you find!

Options

There are several options that let the advanced user configure how sound is displayed on the screen. For most usages, the defaults should work well, however the available options are:

  • Temperament – Equal or Just temperament. This changes the locations of the note annotations and the corresponding tuning indication. (it’s barely noticable)
  • Scaling – Linear or Logarithmic
  • Tuning Frequency – The frequency of A4 which is 440Hz by default.
  • Transposition – Different instruments call the same note note different names. This allows the notes to match your instrument.
  • Autoscaling – When enabled, the display is normalised to the maximum since the last reset. When disabled, every frame is normalised.
  • Advanced Display – Displays a much more technical display. The resolution of the frequencies is higher, the specific detected frequency and note are displayed. The first few formants of the Timbre of the sound are numerically quanitified (multiple of fundamental frequency, relative level (dB)), and the “Dissonance” is calculated.
  • Note Annotations – The scale note (modfied by transposition, tuning, and temperament) is displayed on the circle.
  • Tuner Dot Display – If a note is identified, then the tuning of that note is indicated on the circle.
  • Played Note at Top – If a note is identified, then the fundamental of the note is placed at the top of the circle so that the shape of the Timbre is most evident.

Saving the Images

The images can be saved by navigating to the camera tab, selecting the instant in time in the last 20 seconds, configuring the display options and pressing the save button.

Help Test the Upcoming App!

Subscribe to the mailing list to become a beta tester of Timbre.




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