Modeling and Measurement
Digital Twins for Architecting & Designing Audio Devices
Session 3

High Fidelity Poroacoustic Digital Twin

November 17, 2021
9:00 AM Pacific (12:00 PM Eastern)


The Audio Product Education Institute (APEI) presents the third webinar concluding a series on the practice and benefits of simulation-driven audio architecture design by use of Digital Twins. In this new session, Ulrik Skov (Reality Labs at Meta) shares a “war story” – an example of an actual device development – where a low and high frequency sub-system was architected, design, optimized and troubleshooted over a period of a year struggling with an Industrial Design with a floating display in front of the audio system.
Using Digital Twins systematically through the design and optimization stages of an acoustic device, offers the opportunity to, within few days, upgrade the Digital Twin to design-out complex system level, undesired losses of performance, which normally only an experimental approach would have identified. In the example a significant bouquet of discoveries and insight are presented detailing how a Digital Twin was used to facilitate the creation of the device’s low and high frequency sub-systems. The presentation is concluded by how an unfortunate unexpected dip between 4-6kHz was caused by the cosmetic shell wrapped with fabric. A problem which likely would have taken weeks to months to fix, or in the worst case would not have been corrected with an optimal physical design trade-off between the grills open area and the fabrics acoustic characteristics.
In this session we will learn how the Digital Twin at the end was upgraded to include the perforated shell covered with fabric using the COMSOL multiphysics poroacoustic capabilities. This allowed detecting how the combination of the transducer, front volume, shell holes and fabric caused the transmitted acoustic wave to enter an acoustic mode which resulted in an undesired deep dip at high frequencies. Once the physics were understood it was effortless to find and show a virtual solution, which was experimentally prototyped, verified and implemented. The presentation will explore how this upgraded high-fidelity Digital Twin identified the problem, and allowed the design team to get back on track within few days. 
The webinar will feature a practical demonstration of poroacoustics, poroelastic waves and interior impedance using COMSOL, which represent 3 levels of added complexity/detail to potential model the same phenomena. Attendees will understand the capabilities for modeling porous materials with the functionality of the Acoustics Module in COMSOL and how different models and formulations could be applied. Finally, the session will showcase a method to use parameter estimation to model porous materials.
– Introduction and Problem Description.
– Detailed Presentation of the Journey Architecting, Designing and Optimizing the Low and High Frequency Sub-Systems
– How early findings with the Digital Twin influenced architecture & tuning.
– Use of High-Fidelity Digital Twin with Poroacoustic Losses.
– Poroacoustics, Poroelastic Waves and Interior Impedance in COMSOL.
– Q&A
Previous Sessions
Digital Twins for Architecting & Designing Audio Devices – Session 1 – See recording here
Digital Twins for Architecting & Designing Audio Devices – Session 2 – See recording here
Ulrik Skov

Audio Transducer, System & Material Architectural Lead, Reality Labs at Meta, San Francisco, CA, USA

Since 2018 Ulrik Skov heads-up FRL’s Acoustic Render/Speaker Group. He is an acoustic industry veteran with +25 years of experience from hearing instruments (Oticon), transducer development (Tymphany – ScanSpeak, Vifa and Peerless) and consumer product acoustic module design (Apple – HomePod, AirPods, iPad and iPhone).
Facebook’s Acoustic Render Group is an integrated part of the Technology Engineering Devices (TED) Audio team. The group architects, designs and optimizes acoustic transducers, modules, materials and systems. The Acoustic Render Group heavily front-loads and democratizes decision making by simulation driven working methods and processes via high-fidelity DigitalTwins used throughout the development from early discovery/incubation to late design tweaks and troubleshooting.
This performance focused approach is centered around COMSOLs multiphysics linear and nonlinear capability within the areas of vibroacoustics, thermalacoustics, visco-/hyper-elastics and electromagnetics. Aggressive computational loads are handled by an internally build High Performance Compute Platform where individual engineers have on-the-fly access to queueless and unlimited virtual clusters to collapse mainly 3D multiphysics compute burdens and timelines.

Mads Herring Jensen

Technology Manager, Acoustics, COMSOL
Copenhagen, Denmark

Mads Herring Jensen joined COMSOL in 2011 and is the technology manager for the acoustics products. Mads has a PhD in computational fluid dynamics from the Technical University of Denmark. Before joining COMSOL, he worked in the hearing aid industry for five years as an acoustic finite element expert.

Roger Shively

JJR Acoustics, LLC
Seattle, Washington, USA

Roger is a Co-founder and Principal of JJR Acoustics. He has over 34 years of experience in engineering research and development, with significant experience in product realization and in launching new products at OEM manufacturers around the world. Before co-founding JJR Acoustics in 2011, Roger worked as Chief Engineer of Acoustic Systems as well as functional manager for North American and Asian engineering product development teams in the Automotive Division of Harman International Industries Inc; a journey that began in 1986.
Roger received his degree in Acoustical Engineering from Purdue University in 1983, and finished post-graduate work in the field of finite element analysis. He is a member of the Audio Engineering Society, Acoustical Society of America, and Society of Automotive Engineering. He has published numerous research papers and articles in the areas of transducers, automotive audio, psychoacoustics, and computer modeling. Roger also holds US and International Patents related to the design of advanced acoustic systems and applications particularly in the field of automotive audio. Roger is Co-Chair of the AES Automotive Audio Technical Committee.