[PD] Sound localization

Eran Sachs eransachs at hotmail.com
Mon Dec 10 02:04:52 CET 2012

Mathias, Are you familiar with Interferometry?
Used in localization of electromagnetic signals, among multitude of other applications.
From: m.schaefer at uni-weimar.de
Date: Sun, 9 Dec 2012 23:15:31 +0100
To: pd-list at iem.at
Subject: [PD] Sound localization

Hello people,
I'm trying to build a patch with which I can locate a sound source with  microphones (right now using the Playstation Move Camera with the build in 4 channel microphone array).
So far I found out that there are 3 ways to locate sound sources (correct me if I'm wrong):
1. Energybased method: 
Basically you check the "loudness" of the sound with at least two different microphones in a microphone array. By doing this the microphone which is further away to the sound source gives a signal which is more quiet, so you can roughly determine the location. Problems: 
- You need a completely quiet room for best results 
- Walls reject the sound wave, which gives irregularities
2. Beamforming:
You get the direction of the sound by delaying the array signals and summing them up, thus creating a direction response of the array. How the exact process works and why is a mystery to me so far.
3. Time Delay Estimation-based Localization:
You calculate the delayed time of the amplitudes peaks and get the result in milliseconds. By this you can determine which microphone is closer to the sound source
Attached is a small patch where I tried out the energy based method with the "bonk" utility, the results I get with that are quite sloppy

Anybody there who already tried something with locating sound in pd? Or got any good advice?

Thanks in advance,

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