Active materials for application in room acoustics

Xavier Meynial

doi:10.1117/12.237086

26 April 1996 Active materials for application in room acoustics

Xavier Meynial

Proceedings Volume 2779, 3rd International Conference on Intelligent Materials and 3rd European Conference on Smart Structures and Materials; (1996) https://doi.org/10.1117/12.237086
Event: 3rd International Conference on Intelligent Materials, 1996, Lyon, France

Abstract

This paper presents a preliminary study on the application of the principle of motional feedback to active acoustic materials. The ultimate goal is the application of these materials-- having an adjustable reflection coefficient which may exceed unity--for the control of reverberation in rooms. The present study focuses on the functioning of a cell which comprises a transducer--acting both as a sensor and actuator--placed in an impedance bridge, a filter, and an amplifier. Varying the gain of the amplifier allows control on the reflection coefficient. A model is presented which predicts the functioning of a cell. This model is validated by an experiment in a tube using a traditional moving coil loudspeaker. In this experiment, modulus of the reflection coefficient ranging from 0.5 to 2.3 have been obtained around the resonance frequency of the loudspeaker as predicted by the model. Running the model enables us to define the characteristics of a transducer tailored for our application, specially regarding its moving mass which must be very low.

Citation Download Citation

Xavier Meynial "Active materials for application in room acoustics", Proc. SPIE 2779, 3rd International Conference on Intelligent Materials and 3rd European Conference on Smart Structures and Materials, (26 April 1996); https://doi.org/10.1117/12.237086

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