Supervision: Hervé Lissek,Qin Liu

Project type: Semester project (bachelor)

Available

The Electroacoustic Absorber (EA) concept relies on a closed-box loudspeaker, the membrane of which can be assigned a prescribed acoustic impedance thanks to a microphone-based active feedback control. Once set, the acoustic performance of the EA is usually assessed in an impedance tube under plane waves, following ISO 10534-2 standard with two microphones.

Usually, the control parameters of the EA are identified based on a physical model, assuming the knowledge of the loudspeaker's electroacoustic parameters. However, the identification of these parameters are usually biased, and the environmental conditions (temperature, humidity, etc.) might also change, and this might affect the performance of the concept. But if the controller allows adjusting control parameters on-the-fly, the EA could be made self-adjustable and more robust to these changes. The project proposes to investigate possible means to turn the "fixed" EA into a more adjustable one, thanks to advanced signal processing techniques.

After being initiated to the EA concept and to Speedgoat/Simulink programming, the student will investigate the means to make the controller parameters self-adjustable to the environment, in a view to optimizing the achieved acoustic impedance with respect to a targetted one.

The project will consist of:

• literature review on Electroacoustic Absorbers and on optimization
• development of a model (Simulink) of an EA
• development of signal processing techniques to self-adapt the EA control to unknown and/or time-varying parameters
• experimental set-up to characterize the performance of the EA in an impedance tube, with time-varying conditions

Profile: Electrical engineering

Prerequisites: Electroacoustics (optionally: optimization)

Learning outcome: active control in acoustics, acoustic measurement, Speedgoat programming

Context: Theory/Physical Simulations (30%), measurement (30%), Matlab programming (40%)