2023 Lab tour
2023 is here and we thought we'd share a tour of the lab, highlighting a few of the capabilities we've developed over the years.
Note Magazine Article
IAR was interviewed by Note Magazine on our design involvement with Headphones for the Fall 2021 edition.
Check it out here: https://issuu.com/classicalmusicindy/docs/note-fall2021issue-v04-101821web
Room Acoustics Simulations in Comsol
Within Comsol Multiphysics is the ability to create room acoustics simulations. This can be extremely helpful in shaping the sonic picture of any space. For example, when designing a classroom, if the room is large and has a lot of reflective surfaces, a high reverberation time and low clarity can cause students sitting in the back to have trouble understanding the speaker. By using a simulation, you can test out many acoustic configurations of a room before anything is physically built, saving both time and money, and creating an auditory experience tailored to the needs of the space.
Users build out geometry of the room, adding in carpets, panels, and all other objects. Next, users define absorption coefficients of all materials across frequency bands and map them to different surfaces in the room. After this, the Sabine reverb equation can be calculated as a parametric sweep is simulated.
The room being designed in this case is a room-within-a-room. This will be useful for testing consumer devices in a setting that replicates actual use scenarios. After doing RT60 measurements in Soundcheck 19, it was decided corner bass traps would be a beneficial addition to the room. In Comsol, multiple different bass traps were simulated in different positions to determine best material, placement, and volume to reduce sound reflections in low frequencies with minimal impact in high frequencies.
By: Shannon McConnell
Noise File Comparison Tool
Whether you’re in a teleconference, a live music setting, or simply working in an office, noise and room reverberation time can affect your ability to pleasurably listen. With our new Noise Files Comparison Tool, you can hear and easily compare different kinds of noise to aid in self diagnosing issues quickly and efficiently. For example, you can toggle between 60Hz, Bluetooth, GSM, and Wi-Fi noise interferences to help find the source of unwanted sounds. Also included are different types of broadband and background noise such as pink noise, white noise, city traffic, and a crowded pub.
Additionally, recordings of the in-house Head and Torso Simulator (HATS) playing back an IEEE standard speech file were taken in an anechoic chamber, an acoustically treated room, and a highly reverberant non-acoustically treated room. These can be compared to highlight the impact partial and full acoustic treatment has on speech intelligibility.
We can also use this tool to create custom recordings of your product in different noise conditions, tuning configurations, or other impairments- for subjective evaluation without a trip to our lab. For dB-accurate reproduction we ship you a DAC and Reference Headphones with Comparison Tool files corrected for both the headphone response and binaural HATS Head Related Transfer Function (HRTF).
By: Shannon McConnell
Voice Coil: March 2021 Article
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.
New Bruel & Kjaer 5128 added
3D Printing in-House
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.
Simulation of Microphone Arrays
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.