中文摘要：

蛋鸡声音可用来评价蛋鸡本身的福利状况，然而蛋鸡舍中往往存在着低频风机噪声干扰蛋鸡声音信号的时频特征。为了优化含风机噪声的蛋鸡声音信号，以海兰褐蛋鸡为例，利用数字化声音采集平台，采集了不同的蛋鸡叫声和风机噪声。采用LabVIEW软件，分析了蛋鸡声音和风机噪声的时频特征，同时比较了滤波器和小波去噪方法在去除风机噪声方面的应用效果。结果表明，蛋鸡产蛋期间的声音频率范围为400-2500Hz，而风机噪声的频率在600Hz以内。在信噪比为-20～10dB蛋鸡声音环境中，无限脉冲响应滤波器滤波后的均方根误差要比有限脉冲响应滤波器滤波后的均方根误差小，说明无限脉冲响应滤波器具有更好的滤波效果，与其他小波阈值去噪方法相比，以史坦无偏似然估计为阈值的小波去噪方法在去噪后的均方根误差最小，表明这种方法的去噪效果更好。该研究可为蛋鸡舍中风机噪声环境下的蛋鸡声音识别提供参考。

英文摘要：

Vocalization, which plays an important role in the communication of many animals, could be regarded as an easy way to evaluate the current needs of animals and their state of impaired welfare by non-invasive and continuous monitoring. Modern techniques of sound analysis have provided tools for the quantitative description and statistical analysis of animal vocalization. However, a farmer always regulates the temperature and exchanges fresh air through mechanical ventilation in a poultry house, so that there is often low-frequency fan noise which can complicate the time-frequency features of poultry sound. In order to extract useful sound signals from the laying hens＇ sounds including fan noise, a digitized sound acquisition platform was built to record the pure sounds of laying hens （Hy-Line Variety Brown）, the simple fan noise, and the mixed sounds of them both separately. All data processing and analysis were completed in LabVIEW. First, the time-frequency features of the pure sounds of laying hens, the simple fan noise, and the mixed sounds were analyzed in turn. Then the analog signals of different signal to noise ratios （SNR） were constructed by using the clean sounds of laying hens and fan noise. Finally, the effects of removing fan noise from the analog sound and field sound of laying hens were compared by 2 filters （Infinite Impulse Response, IIR, and Finite Impulse Response, FIR） and 3 wavelet de-noising methods （Stein＇s Unbiased Risk Estimation, SURE, Universal and Minimax）. The results showed that although the characteristic parameters of laying hens＇ vocalization at different growth stages and in different rearing environments were disparate, the main frequency range of the sound of laying hens in the laying period was about 400-2 500 Hz, while the frequency range of fan noise was under 600 Hz. Root mean square errors （RMSE） of the filters under different SNRs were larger than that of the wavelet de-noising methods. The RMSE of the IIR filter was less than that of the FIR fil