Mechanical noise suppression based on non-negative matrix factorization and multi-band spectral subtraction for digital cameras

This paper proposes a new non-stationary noise suppression method to reduce the mechanical noise generated when audio signals are recorded with a digital camera. The proposed method first utilizes a non-negative matrix factorization (NMF) technique to estimate the noise spectrum of the mechanical noise from the noisy audio spectrum. After that, the mechanical noise contaminated in the audio signal is suppressed by multi-band spectral subtraction. In particular, the NMF technique estimates the noise spectrum in a frame-wise manner in order for the proposed method to operate in real-time. The performance of the proposed mechanical noise suppression method is evaluated in terms of log-spectral distortion, cepstral distortion, subjective quality, and computational complexity. In addition, it is compared with the performance of conventional methods. It is shown from the evaluation that the proposed method provides lower log-spectral and cepstral distortions with better subjective preference than conventional methods. Moreover, the complexity of the proposed method is low enough to be implemented on a commercially available digital camera.