Journal of Broadcast Engineering (방송공학회논문지)

The Korean Institute of Broadcast and Media Engineers (한국방송∙미디어공학회)
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Binary Mask Estimation using Training-based SNR Estimation for Improving Speech Intelligibility

음성 명료도 향상을 위한 학습 기반의 신호 대 잡음 비 추정을 이용한 이산 마스크 추정 방법

  • Kim, Gibak (School of Electrical Engineering, Soongsil University)
  • Received : 2012.08.30
  • Accepted : 2012.11.14
  • Published : 2012.11.30
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Abstract

This paper deals with a noise reduction algorithm which uses the binary masking approach in the time-frequency domain to improve speech intelligibility. In the binary masking approach, the noise-corrupted speech is decomposed into time-frequency units. Noise-dominant time-frequency units are removed by setting the corresponding binary masks as "0"s and target-dominant units are retained untouched by assigning mask "1"s. We propose a binary mask estimation by comparing the local signal-to-noise ratio (SNR) to a threshold. The local SNR is estimated by a training-based approach. An optimal threshold is proposed, which is obtained from observing the distribution of the training database. The proposed method is evaluated by normal-hearing subjects and the intelligibility scores are computed by counting the number of words correctly recognized.

본 논문에서는 시간-주파수 영역에서의 이산 마스킹을 이용하여 잡음환경 음성의 음성 명료도를 높이는 방법에 대해 다루고자 한다. 잡음이 섞여 있는 음성신호를 시간-주파수 영역으로 분해하여, 상대적으로 잡음이 많이 섞여 있는 시간-주파수 영역의 신호를 마스크 "0"을 할당하여 제거함으로써 음성명료도를 향상시킬 수 있다. 이러한 이산 마스크를 추정하기 위해서는 각 시간-주파수 영역에서 신호 대 잡음 비를 추정하여 문턱값과 비교해야 하는데, 본 논문에서는 학습 기반의 신호 대 잡음 비 추정방법을 사용하여 문턱값과 비교하여 이산 마스크를 추정한다. 신호 대 잡음 비와 비교하기 위한 문턱값은 모든 주파수 대역에 대해 동일한 값을 이용하는 고정 문턱값 외에도 주파수 대역에 따라 학습 데이터의 분포로부터 최적의 값을 사용하는 최적 문턱값을 제안한다. 제안된 이산 마스크 추정 방법은 잡음 환경 데이터에 적용한 후, 피험자에게 들려주어 음성 명료도를 측정한다.

Keywords

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