Why You Hear What You Hear

 

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MAX patches

written by Jean-Francois Charles

Siren| Partials | Formants| Noisy-Scale

 

How to run a Max patch if the free Max Runtime is not yet installed on your machine.

1. Download the free Max Runtime application. With it, you will be able to run the patches, but not to edit them.

Use a browser to visit http://www.cycling74.com/downloads

Choose either "Current Mac version" or "Current Windows version".

Then, download the most recent version of Max Runtime (not Max itself).

There is currently no Linux version available.

2. Install the application (you need administrator privileges on the computer you are using).

3. Open the patch you want to use.

4. If you think you should hear a sound but don't manage to, check: -did you toggle the "audio on/off" button in the patch?

-did you turn up the "volume" slider in the patch?

-is the audio level high enough on your computer (can you hear system sounds, etc.)?

Jean-Francois Charles' MAX Partials

 

MAX Partials allows arbitrary control over the amplitude, frequency, and phase of up to 50 partials making up a complex tone. This is enough flexibility to perform many experiments, and we shall make use of this application from time to time in different chapters of Why You Hear What You Hear. Autocorrelation and power spectra are plotted and the results can be heard over a speaker system connected to the computer.

The total control of every aspect of the sound trace in MAX Partials makes a large variety of experiments possible. For the present, it is recommended that you construct various periodic and aperiodic waveforms and listen to the results. Try this with predominately low-frequency waveforms, and also predominantly higher frequency examples, above 1000 Hz. Experiment with the changes in quality of tone with the number partials with nonzero amplitude.

We turn to some preliminary exploration and intuition development using MAX Partials. When the program opens, set it for a 200 Hz fundamental, and power up only the lowest 200 Hz partial.

Begin by adding amplitude to the higher partials with the sliders. Since the frequencies remain a harmonic series starting at 200 Hz, the signal, and the autocorrelation function are perfectly periodic.

Now adjust the phases. Notice how much the waveform signal changes. The autocorrelation function does not change.

After each of these phase changes, listen carefully to determine if you can hear any difference in the sound. It is interesting that such different waveforms, as can be produced by changing the phases, can give nearly the same tone.

Set the base frequency lower, to see if the phase changes are any more obvious upon listening to them.

Now adjust the higher partial frequencies, deliberately deviating from harmonic partials. Listen to the differences between aperiodic and periodic sound.

There are dozens of interesting combinations; very useful in connection with beats, pitch, dissonance, etc.

 

Jean-Francois Charles' MAX Formants

Charle's MAX Formants is a "pure formant" synthesizer that can control the center frequency, gain, and frequency width of three formants independently, with sound of course to go along. It requires that you download the free MAX OSX and WIndows runtime software, at http://cycling74.com/downloads/runtime/

Jean-Francois Charles' MAX Siren

Charle's MAX Siren is a flexible It requires that you download the free MAX OSX and WIndows runtime software, at http://cycling74.com/downloads/

Jean-Francois Charles has constructed a platform-independent virtual siren for readers of this book. It is a remarkable learning and research tool, one that acoustic researchers beginning in the 18th century and continuing through the 20th would have given their eye teeth for. Four independent rows of holes are available, with the number of holes, the loudness of each row (corresponding to the pressure supplied to the hose feeding that row) and their relative phases independently adjustable. In addition, the form of the pressure pulses that the hole generates as it passes by the air source is selectable from among some preset values, or, the user may draw in an arbitrary pulse. The rate of spinning of the siren disc is continuously variable over a large range, allowing the pulses to be a few per second or less, in which case they are like a rhythm instrument, up to the top of the audio range. The sounds may be recorded directly to disk for later playback. It is worth spending many hours with this tool.

 

Jean-Francois Charles' MAX Noisy-Scale

This patch allows you to select up to four time delayed (with the time delay set by the user via an on-screen piano keyboard) versions of a given white or pink (louder at lower frequencies) noise signal and listen to the results. The time delays are set to discrete values that give the notes of a musical scale as a repetition pitch.