This paper describes an acoustic system enabling us to achieve asymmetric transmission over a broad frequency range. The basic elements of the are moving coil loudspeaker placed along axis duct, and microphone flush mounted next front side loudspeaker. acts both as mass-spring oscillator through which incident waves reflected transmitted, sound re-emitter controlled by feedback loop. It is show...

The presence of strong acoustic feedback degrades the convergence speed of the active noise control (ANC) filter, and in the worst case the ANC system may become unstable. Here we present an overview of the existing methods developed to neutralize the effects of acoustic feedback. We identify the problems with the existing methods, and propose a new method. The proposed method uses three adapti...

The Feedback Cello is a new electroacoustic actuated instrument in which feedback can be induced independently on each string. Built from retro-fitted acoustic cellos, the signals from electromagnetic pickups sitting under each string are passed to a speaker built into the back of the instrument and to transducers clamped in varying places across the instrument body. Placement of acoustic and m...

The active attenuation of the airborne noise generated from a high-speed CD-ROM system is investigated using model-based feedback control methods. A mathematical model of the physical system is developed based on a onedimensional acoustic duct system. The critical system parameter, acoustic terminal impedance, is estimated using the eigenstructure tests through the system identification method....

The results of a comparative analysis of feedback strategies used in human-human communication and human-machine communication in Swedish are reported in this paper. The aim of this study is twofold: to provide a categorization of feedback expressions based on contextual information and to verify the hypothesis that acoustic characteristics of feedback expressions can be regarded as cues to the...

Acoustic feedback is capable of driving an electroacoustic amplification system unstable. Inserting a frequency shifter into the feedback loop can increase the maximum stable gain before instability. In this paper, we explain how frequency shifting can effectively smooth out the feedback loop magnitude response, and how this relates to the system stability. Then we describe measurements on real...

Human vocal development occurs through two parallel interactive processes that transform infant cries into more mature vocalizations, such as cooing sounds and babbling. First, natural categories of sounds change as the vocal apparatus matures. Second, parental vocal feedback sensitizes infants to certain features of those sounds, and the sounds are modified accordingly. Paradoxically, our clos...

Optimization problem for a structural acoustic model with controls governed by unbounded operators on the state space is considered. This type of controls arises naturally in the context of ”smart material technology”. The main result of the paper provides an optimal synthesis and solvability of associated nonstandard Riccati equations. It is shown that in spite of the unboundedness of control ...