Active control of outgoing noise fields in rooms

Area of Science:

• Acoustics
• Signal Processing
• Vibration Control

Background:

• Existing active noise control (ANC) systems are effective for duct noise but struggle with complex, time-varying room noise fields.
• Tonal noise fields in enclosed spaces present a significant challenge for current noise reduction technologies.

Purpose of the Study:

• To develop an advanced active noise control system capable of suppressing tonal noise fields generated by a primary source within a room.
• To formulate tonal noise field control as the estimation and cancellation of the outgoing sound field on a sphere surrounding the noise source.

Main Methods:

• The proposed system formulates noise control as estimating and canceling the outgoing sound field on a control sphere around the primary source.
• A wave-domain algorithm is employed for controlling the outgoing field, limiting the source's radiated energy.
• The method avoids the need for online secondary path estimation, minimizing interference with desired sound fields.

Main Results:

• Simulations demonstrate the system's efficacy in reducing tonal noise fields within a room.
• Hardware experiments validate the proposed method's ability to achieve significant noise reduction.
• The system proves effective over a wide range of frequencies.

Conclusions:

• The developed active noise control system offers a viable solution for suppressing tonal noise fields in rooms.
• By controlling the outgoing sound field, the system establishes a global quiet zone, enhancing acoustic comfort.
• The approach simplifies implementation by eliminating the requirement for online secondary path estimation.