Electroacoustic Absorbers : from the electric shunting of a loudspeaker to active acoustic impedance control
Event details
| Date | 03.12.2010 |
| Hour | 10:15 |
| Speaker | Dr. Hervé Lissek, Laboratoire d’Electromagnétisme et d’Acoustique, EPFL |
| Location |
ME C2 405
|
| Category | Conferences - Seminars |
Variable acoustic properties can be obtained at the diaphragm of an
electroacoustic transducer, with the help of very basic control
strategies, among which is the simple electrical shunting of the
transducer (shortcut or variable shunt impedance). These passive shunt
techniques are compared to active acoustic feedback techniques aiming
at controlling the acoustic impedance of an electroacoustic transducer.
It is shown here that the formulation of feedback-based acoustic
impedance control reveals singular analogies with shunt strategies, and
highlights an original strategy for synthesizing electric networks
("shunts") with positive or negative components, bridging a gap
between passive and active acoustic impedance control. We present the
theory unifying all these passive and active acoustic impedance control
strategies, introducing the concept of electroacoustic absorbers. The
equivalence between (passive) shunt and active feedback control is
formalized, on the one hand through the introduction of a 1-degree-
of-freedom active acoustic resonator accounting for both electric
shunts and acoustic feedbacks, and on the other hand through the
introduction of equivalent electric networks that mimic the
performances of feedback-based active techniques. Simulations and
experimental results are presented, with an emphasis on formal
analogies between the different acoustic impedance control techniques.
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Practical information
- General public
- Free