Acoustic Localization with 2 Microphones

The purpose of this hobby project is to create a GUI in Laptop, which can perform an acoustic localisation (i.e. detection of a noise source) with 2 microphones connected to TI Launchpad microcontroller (MCU). The animated gif below shows what this program can do, while my iPhone is playing a 500 Hz sine single tone.

Data acquisition in TI TM4C123GXL

• High Performance TM4C123GH6PM MCU

• Communication with Laptop using UART Serial

• Two 12-bit ADCs with 2 microphones KY-037 are used

• MCU with 2 microphones and Webcam (connected to laptop) is shown below

• One can improve the performance of system by using a low pass filter

Theory

There are several ways of implementing beamforming and I took the simplest one, which uses a phase difference between two microphones.

At a given frequency, one can calculate a direction of incoming sound based on the phase difference between two microphones and this phase information can be obtained from the cross-spectrum of two microphone signals.

Graphical User Interface in C#

GUI is written in C# and its main function is to get the phase between two microphones from TI Launchpad, and to dispaly it together with an webcam image in real time.

• The version of Visual studio is Community 2019
  • NET Framework 4.7.2
  • WinForms (Not WPF)
• Frequency domain data: Phase information
  • Number of FFT line: 128
  • Highest frequency: up to 2048 Hz, but surely, the data between 1700 Hz and 2048 Hz would be contaminated with an aliasing
  • The cross-spectrum of two inputs are done with CMSIS DSP library
• Webcam image
  • AForge / AForge.Video / AForge.Video.DirectShow
  • Those packages are available in NuGet Packages

Open points

• Show FFT spectrum from two microhpones
• Use a contour plot instead of a single red line, in order to show the location of noise source

Remarks

Some parts of C# codes are got from internet search and I always tried to copy the codes with reference and without violating any copyright. Nevertheless, please let me know if there is any possible copyright infringement issue in the codes. Then, I will remove it from the repository immediately.