Indy Acoustic Research collaborated with Listen, Inc. to bring the data behind the article "How to Measure Free-Field Speaker Response without an Anechoic Chamber" featured in the March 2021 Voice Coil article, linked below!

The hybrid splice method of loudspeaker frequency response measurement compares well with an anechoic chamber for a single loudspeaker if the splice frequency can be determined. However, complex devices require the greater flexibility in setup conditions and off-angle measurements afforded by a full chamber. 

To speed iterative prototyping and fixture creation for some assemblies and housings, IAR has brought reliable and low-cost FDM prototyping in-house. Common items we print include speaker baffle adapters, customer housing mockups for probe microphone measurements, or other fixtures to support device assembly or measurements. Maximum print size on this device is approximately 9 x 8 x 8 inches. High-resolution SLA and smaller assemblies will continue to be sourced from a handful of Indianapolis-based prototyping shops.

 Many far-field voice devices employ beamforming microphone arrays to improve speech recognition and communication performance. However, often the simulation of the acoustic wave during DSP design only includes phase differences due to array spacing and neglects more complex geometry such as element porting, enclosures, tables or walls.  These objects cause diffraction and reflections of the incoming acoustic wave around the sensor can lead to errors in beamforming and direction-of-arrival algorithms. IAR can use Comsol Multiphysics or Lumped Element Simulation (depending upon the complexity of geometry, frequency range of interest and available time) to provide simulated complex acoustic pressure “vectors” to DSP designers to improve the performance of the array including geometric features, prior to any prototype production or PCB fabrication.

By: Marc Reese and Larry Marcus
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Indy Acoustic Research celebrates its first year! 

A lot of effort has gone this year into building our lab's capabilities to ensure we can support our customer's needs and timing. Below are some pictures of some of our activities in the past few months.

​Excel is a great tool for engineering data reporting due to its widespread use. However, it has never supported a good polar plot which is an essential plot type in multiple engineering disciplines, including acoustics.  The major workarounds I’ve seen are to either download a plugin (which is difficult if you don’t have admin rights) or convert (theta,R) into x=R*cos(theta) and y=R*sin(theta) and use a scatter plot. However, the latter method can take up a lot of spreadsheet space -especially if you have multiple sets of data.
 
It turns out the chart type that you always thought should be able to plot a polar – the Radar Chart – CAN do it; however, there is still some frustration with the formatting of axes. Thankfully, if you work through the frustration once and save the completed chart as a template, it’s much easier to reuse future data sets. See the below attachment for instructions using Excel 2016. There are some differences with older versions, but hopefully you can follow along also...
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IAR has moved back into the old lab!  The lab has a fully anechoic chamber for far-field devices, Head and Torso simulator (HATS) for near field devices and diffuse field booth for noise isolation measurements. And yes, some desk space for sippin' coffee.