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Compact, Multi-Directional Microphone for Accurate Acoustic Testing

Identifies and Analyzes Sound Sources, Intensities, and Localization Using a MEMS-Based Acoustic Array

This multi-directional microphone combines a small silicon piezoresistive microphone with an instrumentation amplifier to produce a modular, “all-in-one” microphone chip that enables faster, cheaper, more accurate acoustic noise testing. This acoustic combination can serve as a dynamic pressure sensor and a microelectromechanical systems (MEMS)-based acoustic array. Initially, University of Florida and NASA researchers sought to design a MEMS-based acoustic array to measure noise in wind tunnel testing of aircraft, sound field mapping for automobiles, and general acoustics, realizing that it could apply to a much wider market if they made it small and inexpensive. At that time, acoustic arrays comprised individual components, such as a microphone, amplifier, data acquisition system, and computer. UF and NASA researchers built a compact, easy-to-use, portable unit that contained all those elements in one self-contained printed circuit board acoustic array.


This modular microphone chip is a compact, portable, multi-directional microphone that accurately tests and analyzes acoustics and includes all components in one. These chips are integrated into a circuit board to produce an acoustic array and allow for the addition of standard DSP chips to perform real-time acoustic array processing (e.g. beamforming, frequency analysis, adaptive source localization). This “all-in-one” acoustic array measurement tool is so sensitive it can measure not only the location of a person talking but also the heartbeat of the person talking.

 

Application

Fast, inexpensive acoustic noise analyses with real-time digital signal processing

 

Advantages

  • Uses inexpensive, batch-fabricated piezoresistive microphones and standard instrumentation amplifiers, saving thousands of dollars per microphone channel
  • Integrates microphone and amplifier into a single chip, reducing electrical noise problems and greatly improving acoustic accuracy
  • Uses commercially available real-time digital signal processing solutions, providing almost instant results

Technology

An acoustic array is a collection of spatially distributed microphones used to measure an acoustic field. The time signals from each microphone are selectively weighted and delayed through a signal processing technique known as beamforming, which provides the array with a directional response then electronically “steered” in space. Each microphone senses a slightly different phase-shifted waveform depending on its distance from the source. In addition to the acoustic array, the multi-directional microphone includes a combination of microphones, amplifiers, substrates and circuits and a piezoresistive transduction scheme that can transduce a lower minimum detectable pressure, is more environmentally stable, and is easily fabricated.

Patent Information:
App Type: Patent No.: Patent Status:
ORD/UTIL 7,092,539 Issued