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Hardware setup for perimeter array of microphones

Choosing microphones

Before you can do cool things such as beamforming by processing signals from microphones, you need a wayto gather the signals. A few essentials components in this are the microphones themselves, the analog-to-digital converter, and inmany cases a preamplifier for the microphones.

The type of microphones we used in our project were Electret Microphone Elements. We chose these because they:

  • are omni-directional
  • have a good, even, frequency response
  • run off a battery
  • are small (and inexpensive too)

Data acquisition

The analog-to-digital converter we used was a DAQPad device generously lent to us by National Instruments.


The DAQ device requires an input signal of 50 mV to 10V, and the Microphone Elements output signals in the 20-200μV range. So we built preamplifiers that took in the signal from the microphones and amplified it 3158.44x. We used LM324quad-operational amplifiers, with 56.2 kOhm and 1 kOhm resistors. At the inputs of each amplifier is a 2.2 uF capacitor designed to eliminate a slight DC offset produced by each microphone.

Preamplifier schematic with lm324

The configuration for preamplifiers with a LM324 opamp.

Putting it all together

The next step is putting everything together. We built the perimeter array of microphone in a shallow box. To make a perimeter array we put 8 microphones in a pattern around the edge of a square 5.5 centimeters apart. The preamps and batteries were housed under the box, with the outputs coming from the side to connect to the DAQ card.

Microphone perimeter array

The box housing the perimeter microphone array and preamps.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Elec 301 projects fall 2005. OpenStax CNX. Sep 25, 2007 Download for free at http://cnx.org/content/col10380/1.3
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