These files are part of a project to measure material absorption coefficients.

Includes a program to analyse transfer function or absorption coefficient from a set of recordings (tf_from_rec.py):

Example

python tf_from_rec.py white_foam.aup 3 2 -f 100 4000 -e -n 32 -a 0.1

Use spectra calculated from white noise loops contained in white_foam.aup in channels 3 and 2:

• white_foam.aup: audio file (only audacity for now), depends on audacity.py
• 3 2: use channels 3 and 2 (more channel pairs can be added for comparison)
• -f 100 400: excitation noise is bandlimitted to 100-4000 Hz
• -e: plot spectral error
• -l 4096: excitation noise loop is 4096 samples long
• -n 32: use the first 32 loops
• -a 0.1: microphone distance is 0.1 m
  • -a 0.1 345, similar but change speed of sound to 345 m/s

When comparing several measurements use:

python tf_from_rec.py audio1.aup 3 2 5 4 audio2.aup 1 0 [more options]

means:

• use channels 3 and 2 from audio1.aup
• use channels 5 and 4 from audio1.aup
• use channels 1 and 0 from audio2.aup

python tf_from_rec.py white_foam.aup 0 1 2 -f 100 4000 -e -n 32 -a 0.1

Means: measure transfer function between channels 1 and 0 and between channels 2 and 0

to be added later