Design of Effective Noise Cancellation Circuits in Acoustic
To-Po Wang1, Yen-Chu Lee2
1To-Po Wang, Department of Electronic Engineering and Graduate Institute of Computer and Communication Engineering, National Taipei University of Technology, Taipei, Taiwan.
2Yen-Chu Lee, Department of Electronic Engineering and Graduate Institute of Computer and Communication Engineering, National Taipei University of Technology, Taipei, Taiwan.
Manuscript received on June 10, 2014. | Revised Manuscript Received on June 12, 2014. | Manuscript published on June 18, 2014. | PP: 01-03 | Volume-1, Issue-7, June 2014.
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: This paper presents an effective noise cancellation circuit in acoustic, which is designed, simulated, and measured. The feedforward earphone is with high performance of noise suppression. The main structure consists of a controller, a notch filter, a high-pass filter, a microphone, and a speaker. The noise detection microphones pick up sounds and divide them into human voice and low-frequency noise. After passing through the gain-controlled filters, the embedded filtered-X least mean-square (FxLMS) algorithm will generate anti-noise signals with 180° phase difference to ambient noise. Consequently, these anti-noise signals will be transformed from digital formats to analog format, and thereby transformed to acoustic signal by the speakers. The generated acoustic signal will cancel the ambient noise, leading to a quiet zone. According to the measured results, it is indicated that a 15-dB noise reduction is achieved.
Keywords: Active noise cancellation, low-frequency noise, feed forward type, feedback type.