tailieunhanh - báo cáo hóa học: " Noise reduction for periodic signals using highresolution frequency analysis"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Noise reduction for periodic signals using highresolution frequency analysis | Yoshizawa et al. EURASIP Journal on Audio Speech and Music Processing 2011 2011 5 http content 2011 1 5 D EURASIP Journal on Audio Speech and Music Processing a SpringerOpen Journal RESEARCH Open Access Noise reduction for periodic signals using high-resolution frequency analysis Toshio Yoshizawa Shigeki Hirobayashi and Tadanobu Misawa Abstract The spectrum subtraction method is one of the most common methods by which to remove noise from a spectrum. Like many noise reduction methods the spectrum subtraction method uses discrete Fourier transform DFT for frequency analysis. There is generally a trade-off between frequency and time resolution in DFT. If the frequency resolution is low then the noise spectrum can overlap with the signal source spectrum which makes it difficult to extract the latter signal. Similarly if the time resolution is low rapid frequency variations cannot be detected. In order to solve this problem as a frequency analysis method we have applied non-harmonic analysis NHA which has high accuracy for detached frequency components and is only slightly affected by the frame length. Therefore we examined the effect of the frequency resolution on noise reduction using NHA rather than DFT as the preprocessing step of the noise reduction process. The accuracy in extracting single sinusoidal waves from a noisy environment was first investigated. The accuracy of NHA was found to be higher than the theoretical upper limit of DFT. The effectiveness of NHA and DFT in extracting music from a noisy environment was then investigated. In this case NHA was found to be superior to DFT providing an approximately 2 dB improvement in SNR. 1. Introduction Noise reduction to recover a target signal from an input waveform is important in a number of fields. We usually use a frequency spectrum to remove noise from the input waveform. Although it is difficult to distinguish a signal from the noise in the time domain this task tends to become .

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