Practical active and semi-active strategies for the control of room acoustics in the low frequency range

Modal acoustics is one of the main sources of annoyance in the low frequency range in rooms. Active noise control techniques can be deployed to reach sufficient acoustic benefit, but limited to a single frequency, whereas broader efficiency would require complex systems with a large number of transducers. After a short presentation of the state-of-the-art active modal control techniques, this paper will introduce the semi-active concept of “electroacoustic absorbers”, which are able to handle low-frequency room acoustics problems along significant frequency bandwidth, in the experimental context of the damping of the first modal frequencies of a test chamber. This study will focus on highlighting advantages and drawbacks of such techniques when compared to active strategies (performances, complexity,…), concluding with practical consideration (integration, cost,…).