Spectral and vibration response tests on wooden planks

These are tests made on eight wooden planks (silver fir), ca. 10 cm wide, 2 cm thick, length variable between 150 and 230 cm. They were placed on a bubble wrap.

2014-06-18 10.55.39.jpg

I sent two different signals travelling through the eight vibro speakers (Mighty Dwarfs, attached to the planks via tape). Both signals were controlled via a Max/MSP patch (something between a drum machine and a granulator) which could modulate the pitch and amplitude envelope of each grain, and the duration and tempo over time.

1. Sine wave (varying around 60 Hz) continuously travelling from channel 1 to 8.

  1. Download here the 8-channel file used for the test.
  2. Download here the stereo mixdown of the previous file used for the sonogram.
  3. Download here the stereo recording (ZOOM H4) of the wooden planks resonating.

Sonogram of the original file (stereo mixdown):

Sine - clean


Sonogram of the resonating wooden planks:

Sine - wood

As you can see, the wood resonates with a lot of harmonics and side-noises (other objects were probably resonating as well) even if we send a “pure” sine wave.

2. Sawtooth wave, two sets: one around 60 Hz, travelling from channels 1 to 4; the other slightly higher (one semitone), traveling from channel 5 to 8.

  1. Download here the 8-channel file used for the test.
  2. Download here the stereo mixdown of the previous file used for the sonogram.
  3. Download here the stereo recording (ZOOM H4) of the wooden planks resonating.

https://drive.google.com/file/d//edit?usp=sharing

Sonogram of the original file (stereo mixdown):

Sawtooth - clean


Sonogram of the resonating wooden planks:

Sawtooth - wood

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3 pensieri su “Spectral and vibration response tests on wooden planks

  1. If you had cut the planks in mathematical proportions, Pythagoras might have emerged from his grave to sing along. The graphs would have shown it, no?

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