利用水下声音测量系统(带宽20 Hz^24 k Hz)分别记录了浙江省象山县西沪港和福建省福鼎市沙埕港网箱养殖大黄鱼的水下声音和行为反应,并对声音数据进行频谱分析和声压级(SPL,d B:re 1μPa)计算。结果显示:(1)网箱周围水下声音主要为,自...利用水下声音测量系统(带宽20 Hz^24 k Hz)分别记录了浙江省象山县西沪港和福建省福鼎市沙埕港网箱养殖大黄鱼的水下声音和行为反应,并对声音数据进行频谱分析和声压级(SPL,d B:re 1μPa)计算。结果显示:(1)网箱周围水下声音主要为,自然环境噪声(风、波浪,500 Hz^24 k Hz)、大黄鱼生物噪声(惊扰发声主峰值630 Hz、摄食发声主峰值800 Hz、游泳噪声50~400 Hz、摄食噪声20~2 200 Hz)和人为噪声(船舶噪声50~500 Hz);(2)船舶噪声SPL(约87.68 d B)低于部分石首鱼科听觉阈值(94.9~99.6 d B:re 1μPa),不影响大黄鱼声通讯和摄食行为;(3)网箱内生物噪声声压级强度:惊扰状态>摄食状态>背景噪声。结果表明,大黄鱼生物噪声频率主峰值和声压级强度与行为反应有关,即行为反应程度越激烈,频率主峰值越低,声压级强度越高。展开更多
Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity ...Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity of marine environment and the particularity of underwater acoustic channel,noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing.In order to solve the dilemma,we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN),minimum mean square variance criterion(MMSVC) and least mean square adaptive filter(LMSAF).This noise reduction technique,named CEEMDAN-MMSVC-LMSAF,has three main advantages:(i) as an improved algorithm of empirical mode decomposition(EMD) and ensemble EMD(EEMD),CEEMDAN can better suppress mode mixing,and can avoid selecting the number of decomposition in variational mode decomposition(VMD);(ii) MMSVC can identify noisy intrinsic mode function(IMF),and can avoid selecting thresholds of different permutation entropies;(iii) for noise reduction of noisy IMFs,LMSAF overcomes the selection of deco mposition number and basis function for wavelet noise reduction.Firstly,CEEMDAN decomposes the original signal into IMFs,which can be divided into noisy IMFs and real IMFs.Then,MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs.Finally,both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained.Compared with other noise reduction techniques,the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals,which has the better noise reduction effect and has practical application value.CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection,feature extraction,classification and recognition of underwater acoustic signals.展开更多
为保障长江通航能力,抛石作为航道整治的一种常用方式而被频繁实施。为了探索抛石产生的水下噪声特征及其对长江江豚的潜在影响,采集了4种不同类型的抛石施工产生的水下噪声,分析声信号的声压级、功率谱密度等。结果表明,抛石噪声的声...为保障长江通航能力,抛石作为航道整治的一种常用方式而被频繁实施。为了探索抛石产生的水下噪声特征及其对长江江豚的潜在影响,采集了4种不同类型的抛石施工产生的水下噪声,分析声信号的声压级、功率谱密度等。结果表明,抛石噪声的声源级均大于151 d B;能量主要集中于中低频(<20 k Hz)部分;20~100 k Hz频率范围的声压级均大于45 d B;记录到的1/3倍频程声压级在绝大多数频率处都高于长江江豚听觉阈值,说明抛石噪声可被江豚感知。结合长江江豚声信号及听觉特性,认为抛石噪声可能会压缩长江江豚的自然栖息地;对幼年长江江豚造成伤害的可能性较大;对长江江豚的听觉可能造成不利影响。最后基于分析结果提出了缓解方案。展开更多
文摘利用水下声音测量系统(带宽20 Hz^24 k Hz)分别记录了浙江省象山县西沪港和福建省福鼎市沙埕港网箱养殖大黄鱼的水下声音和行为反应,并对声音数据进行频谱分析和声压级(SPL,d B:re 1μPa)计算。结果显示:(1)网箱周围水下声音主要为,自然环境噪声(风、波浪,500 Hz^24 k Hz)、大黄鱼生物噪声(惊扰发声主峰值630 Hz、摄食发声主峰值800 Hz、游泳噪声50~400 Hz、摄食噪声20~2 200 Hz)和人为噪声(船舶噪声50~500 Hz);(2)船舶噪声SPL(约87.68 d B)低于部分石首鱼科听觉阈值(94.9~99.6 d B:re 1μPa),不影响大黄鱼声通讯和摄食行为;(3)网箱内生物噪声声压级强度:惊扰状态>摄食状态>背景噪声。结果表明,大黄鱼生物噪声频率主峰值和声压级强度与行为反应有关,即行为反应程度越激烈,频率主峰值越低,声压级强度越高。
基金The authors gratefully acknowledge the support of the National Natural Science Foundation of China(No.11574250).
文摘Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity of marine environment and the particularity of underwater acoustic channel,noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing.In order to solve the dilemma,we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN),minimum mean square variance criterion(MMSVC) and least mean square adaptive filter(LMSAF).This noise reduction technique,named CEEMDAN-MMSVC-LMSAF,has three main advantages:(i) as an improved algorithm of empirical mode decomposition(EMD) and ensemble EMD(EEMD),CEEMDAN can better suppress mode mixing,and can avoid selecting the number of decomposition in variational mode decomposition(VMD);(ii) MMSVC can identify noisy intrinsic mode function(IMF),and can avoid selecting thresholds of different permutation entropies;(iii) for noise reduction of noisy IMFs,LMSAF overcomes the selection of deco mposition number and basis function for wavelet noise reduction.Firstly,CEEMDAN decomposes the original signal into IMFs,which can be divided into noisy IMFs and real IMFs.Then,MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs.Finally,both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained.Compared with other noise reduction techniques,the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals,which has the better noise reduction effect and has practical application value.CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection,feature extraction,classification and recognition of underwater acoustic signals.
文摘为保障长江通航能力,抛石作为航道整治的一种常用方式而被频繁实施。为了探索抛石产生的水下噪声特征及其对长江江豚的潜在影响,采集了4种不同类型的抛石施工产生的水下噪声,分析声信号的声压级、功率谱密度等。结果表明,抛石噪声的声源级均大于151 d B;能量主要集中于中低频(<20 k Hz)部分;20~100 k Hz频率范围的声压级均大于45 d B;记录到的1/3倍频程声压级在绝大多数频率处都高于长江江豚听觉阈值,说明抛石噪声可被江豚感知。结合长江江豚声信号及听觉特性,认为抛石噪声可能会压缩长江江豚的自然栖息地;对幼年长江江豚造成伤害的可能性较大;对长江江豚的听觉可能造成不利影响。最后基于分析结果提出了缓解方案。
