resources

The following is a sample of sound recordings and scripts in no particular order that are fairly self explanatory. Of course, I must give the disclaimer that while I take every effort to put my scripts through their paces and double check for errors, nothing is guaranteed. If you find something wrong, please send an email pointing out the error so I can fix it.

Sound

chicago metra track number 5.mp3
Binaural sound field recording made in the waiting area of the Chicago Metra's LaSalle Street station.

Background Noise Files (click to play)
A set of .mp3 files of broadband noise shaped to match the preferred noise criterion (PNC) and noise rating (NR) background noise curves. Played over headphones, the files can be used to compare the difference in tonal shaping and change in level between criteria. If the files are played over loudspeakers, one file can be calibrated with a sound level meter for accurate reproduction of each level. The files are calibrated to full scale for the 31.5 Hz value of NR-55, so the rest of them are quite low in volume. CAUTION: There is very heavy low-frequency content in these files!

Matlab Scripts

butterfilt.m
A function taking a wave file and filtering it with a hi-, low-, or bandpass butterworth filter according to cuttoff frequency and order.

microperf.m
Script to calculate the acoustic absorption function of a microperforated material according to: Dah-You Maa, Potential of microperforated panel absorber. J. Acoust. Soc. Am. Volume 104, Issue 5, pp. 2861-2866 (November 1998) Issue Date: November 1998

background noise criteria.zip
A set of simple matlab scripts that return the background noise level of an octave-band spectrum as measured by the Noise Criterion (NC), Preferred Noise Crieterion (PNC), or Room Criteria (RC) metrics.

Pure Data patches

intensity_probe.pd
A pure data patch that can turn a matched pair of microphones into an (uncalibrated) intensity probe. Slide and plot show amplitude and direction of travel (positive or negative). To use, wrap two microphones together and enter the distance between capsules as indicated in the patch and plug into your audio card.

zaireeka.pd
A pure data patch for listening to The Flaming Lips' four disc album Zaireeka. To use: (1) rip each disc into wave files, (2) place wave files from each disc into separate folders labeled "zaireeka1", "zaireeka2", "zaireeka3","zaireeka4", (3) rename the tracks in each folder to "1.wav", "2.wav",..."8.wav", (4) place the PD patch in the same folder as the "zaireeka" folders, (5) open the patch, connect your four channel audio card, click the circle next to the track you want to hear, and hit play. Loudspeakers not included.

All content © 2012 Clemeth Abercrombie. Site design by abiagi.