Volume 7, Issue 5, September 2018, Page: 103-118
Benefits and Limitations of Common Directional Microphones in Real-World Sounds
Xubao Zhang, Research & Development, Sonova Unitron, Oticon, Canada; Electronic Engineering Department, Xi’an Electronic Science and Technology University, Xi’an, China
Received: Sep. 6, 2018;       Accepted: Sep. 26, 2018;       Published: Oct. 26, 2018
DOI: 10.11648/j.cmr.20180705.12      View  263      Downloads  5
Abstract
We present extensive experimental data to objectively evaluate the benefits and limitations of common directional microphones in real-world sound fields. The microphones include a conventional directional microphone(DM), a balanced DM, etc., plus the Omni microphone (mic) as a benchmark. The evaluation focuses on noise outputs, signal-to-noise ratios(S/Ns) and distortions; the real-world sounds include male voices, female voices, babble noises, white noises and talking interferences. Each type of noises is at 4 or 5 levels, from 30 to 70 dB SPL, at 10 dB step, and each talking interference is at 3 levels: 50, 60 and 70 dB SPL. The research methods include analytically deriving sensitivity-gains, statistically calculating the three mics’ outputs, experimentally viewing waveforms and spectra, and using large-sample wave files for a high confidence level. According to the experimental results, this paper concludes that 1) for a conversation in a quiet field, in soft or low noise field, the common DMs achieve comfortable S/Ns: 7 to 33 dB, similar to what the Omni mic does; 2) for a conversation in low, competing or strong talking interference fields, the common DMs achieve about 16 dB better S/N than the Omni mic does; 3) for a conversation in competing or strong surrounding noise field, the common DMs do not achieve beneficial S/N to understand speech; the common DMs’ noises are close to the Omni mic noise; 4) in various experiments, the balanced DM preserve speech fidelity well as the Omni mic does, while the conventional DM does poorly. This paper further introduces the Simulink experimental manipulations, such as digital FIR filters’ design, stereo channels’ wave files creation, etc., in the Appendix.
Keywords
Directional Microphone, Speech Enhancement, Noise Suppression, Distortion and Simulink
To cite this article
Xubao Zhang, Benefits and Limitations of Common Directional Microphones in Real-World Sounds, Clinical Medicine Research. Vol. 7, No. 5, 2018, pp. 103-118. doi: 10.11648/j.cmr.20180705.12
Copyright
Copyright © 2018 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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