Active Control of Environmental Noise, Ii: Non-Compact Acoustic Sources

Active Control of Environmental Noise, Vii: Performance of Multi-Frequency, Multi-Channel, Freefield Sound Cancelling Systems

“…as predicted by equations (A45) and (A46) in reference [2]. Here, is the acoustic wavelength and N N is the number of discrete primary sources within the source length¸N.…”

“…To compare the acoustic performance of real hardware implemented adaptive systems with theory, the sound pressure characteristics were computed using acoustic wave equations used to establish the acoustic properties in references [1,2]. The system dimensions were chosen so that the acoustic characteristics could be computed and then compared with the measurements made in the laboratory.…”

Potential-based methodology for active sound control in three dimensional settings

“…One should note here that apart from the JMC, there are a number of other noise abatement techniques, which provide for the cancellation of noise in selected discrete 18,19 or directional areas. 20 In contrast to many other active noise control techniques, the potential-based ASC can naturally be realized in a discrete form 12 via the Difference Potential Method (DPM) formalism. From the standpoint of practical implementation, this is a clear advantageous because a realistic ASC system would require a discrete collection of control sources.…”

Active Control of Environmental Noise, Vi: Performance of a Fundamental Free-Field Sound Cancelling System

“…The basic wave theory using computer modelling, and point acoustic sources in free-"eld was reported in reference [1]. The theory was extended to complex high-frequency sound from large non-compact sources in reference [2]. The implementation of the wave theory into hardware was considered in reference [3].…”