Electroacoustic Absorbers I: Bridging a Gap between Active Sound Absorption and Shunt Loudspeakers
نویسندگان
چکیده
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. These shunt techniques are compared to active feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. It is shown here that the formulation of feedback-based acoustic impedance control reveals formal analogies with shunt strategies, and highlights an interesting strategy for synthesizing electric networks capable of mimicking feedbacks on actual acoustic quantities, bridging a gap between passive and active acoustic impedance control. The present paper describes the underlying theory unifying all these passive and active acoustic impedance control strategies, introducing the concept of “electroacoustic absorber”. The formal equivalence between shunt and active feedback control is first 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 acoustic feedbacks. Simulated acoustic performances are presented, followed by discussions on the design of active electric shunts in view of active sound absorption. At last, experimental assessments of the studied configurations are presented, with general discussions on the concept.
منابع مشابه
Electroacoustic absorbers: bridging the gap between shunt loudspeakers and active sound absorption.
The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance co...
متن کاملAcoustic Impedance Synthesis at the Di- Aphragm of Moving Coil Loudspeakers Using Output Feedback Control
This paper discusses a time-domain technique for synthesizing acoustic impedance at the diaphragm of a loudspeaker using a proportional-plus-derivative output feedback. The dynamics of electroacoustic transducers such as moving-coil loudspeakers can be readily controlled either by direct feedback principle on acoustic quantities, or by plugging a shunt network at the electrical terminals. Any c...
متن کاملElectroacoustic absorbers for the low-frequency modal equalization of a room: what is the optimal target impedance for maximum modal damping, depending on the total area of absorbers?
Electroacoustic absorbers consist of loudspeakers, shunted with an electrical circuit designed to obtain a given acoustic impedance. Their design and principles are now well understood. Unidimensional experiments, using plane waves under normal incidence in ducts, agree perfectly with simulations and confirm the validity of the model: the low-frequency absorption is maximal (and total) when the...
متن کاملExperimental study and modelling of date palm fibre composite acoustic behaviour using differential evolution algorithm
Background and aims: In recent years, in most countries of the world, the provision of a calming environment without disturbing noise has become a need, which has subsequently led to significant growth in noise control techniques. It is now well documented that prolonged over-exposure to the excessive levels of environmental noise not only induces disabling hearing impairment but also contribut...
متن کامل