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1、基于耳蜗模型的舰船噪声谱分析谢骏，胡均川，笪良龙，李玉阳（海军潜艇学院战术水声环境数据中心，山东青岛 266071）摘 要：为提取舰船噪声听觉特征，应用被动长波模型对舰船噪声进行了分析，得到噪声信号的二维时空分布。给出了4种一维特征，它们能够分别从不同侧面反映舰船噪声时频幅特征，同时简化了特征的描述方式。大量实验表明，基于听觉模型特征分析结果，较全面的反映了舰船噪声的听觉特征，为被动声纳目标识别提供了新的特征分析方法。关键词：耳蜗模型；被动长波模型；舰船噪声；特征提取；被动声纳；水下目标识别；听觉感知中图分类号：TP391.9 文献标识码：A 文章编号： Spectrum analysis b
2、ased on cochlea model for naval vessel radiation noise XIE Jun,HUN Jun-chuan,DA Lianglong,LI Yuyang(Naval Submarine Academy Tactical Underwater Acoustical Database Center,QingDao 266071, China)Abstract：A passive long wave cochlea model is applied to extract audial feature of naval vessel radiation n
3、oise. Based on the model, a two dimensional time space distribution Spectrum of noise signal is calculated. Four one dimensional features with simple form are presented. The experiment results shows that the features based on cochlea model is consistent with auditory perception of noise signal. The
4、approach is a new method to extract feature for passive sonar target recognition. Key words：cochlea model ; passive long wave model; navy vessels noise; feature abstract；passive sonar ; underwater target recognition; auditory perception引 言收稿日期：xxxx-xx-xx 修回日期：xxxx-xx-xx 基金项目：国防预研基金，51303060403-01；新世
5、纪优秀人才支持计划NCET。作者简介：谢 骏(1976-), 男, 安徽颍上, 汉, 博士在读, 讲师, 研究方向为声纳环境效应仿真、水下目标特性分析。被动声纳目标识别问题是水声信号处理领域的突出难题之一。被动声纳目标识别研究对象通常是舰船噪声信号序列，它被认为是局部平稳的宽带随机过程，主要由螺旋桨噪声、机械噪声和水动力噪声组成。舰船噪声信号产生机理的研究取得了一些成果14，对特征提取和分类器设计有一定指导意义。更多的研究集中在对舰船噪声信号的分析方面，主要包括时域、频域和时频联合域，其中基于LOFAR和DEMON的频域分析技术在国内外识别系统中得到了广泛应用59。近年来，一些现代信号处理技术
6、被引入目标识别领域，一方面用于改进LOFAR和DMEON分析，另一方面主要是针对舰船噪声非线性特性的分析。当前，水下目标识别领域具有稳健性和明确物理意义的特征很缺乏，除了转速特征外，提取声纳员使用的听觉特征是一个值得研究的问题。随着听觉科学的发展，听觉生理和听觉心理研究取得了大量的成果，在语音识别领域中得到了广泛的应用10。将听觉科学的研究成果应用到对舰船噪声信号中，分析声纳员听觉分类时频幅特征，对提高被动声纳目标识别系统的性能意义重大。1 耳蜗模型原理人耳是优良的声信号分析处理器。人耳外周器官主要可分为外耳、中耳、内耳三个部份，连同各级听觉中枢，构成了人类的听觉系统。其中外周器官是一个复杂的
7、生物力学系统，并在内耳转化成一个复杂的生物电子器官。在对人耳感声机理的研究中，通常认为声波到达内耳前的部分是个简单的线性滤波器，内耳的耳蜗是重要的声音的感知器官，它能完成能量转换功能，产生能被中枢神经系统所接受和处理的生物电脉冲序列，同时它也具有很强的信号处理能力，能将声信号的频率、强度、瞬时特征等重要信息编码听神经生物电序列的时间空间分布之中。有关人耳感声机理的学说是建立在耳蜗解剖学基础上的，比较著名的有Helmholtz的听觉部位共振学说、Rutherford的频率学说和Bksy的行波理论等。Bksy对耳蜗基底膜振动的直接观察和其行波理论的提出，成为耳蜗频率分析器基础理论的重要依据。行波理
8、论指出特定频率的声音会引起耳蜗底回基底膜的振动，并以行波方式向蜗顶推移。在推移过程中基底膜的振动幅度逐渐增大，并在某一特定部位达到最大，然后迅速衰减并消失。产生最大振动的部位决定于声音的频率，高频声在耳蜗底部，低频声在耳蜗顶部。基底膜对声信号的响应相当于使其通过一系列的低通滤波组11。依据听觉科学的研究成果总结出一种人耳听觉感知的被动长波耳蜗模型1214。该模型力图从整体上描述听觉外周器官对声信号的处理。该模型把外耳和中耳看成是个简单的线性滤波器，把内耳主要分为基底膜低通滤波器、内毛细胞半波整流和自动增益控制3个部分。其中基底膜低通滤波器，用二阶零极点模型近似：其总体结构图如图1所示。图1 被
9、动长波听觉模型2 基于耳蜗模型的舰船噪声信号分析长期以来舰船噪声的目标识别主要依赖于训练有素的声纳员，声纳员往往能根据这些特殊音色特征迅速、正确的进行分类判决。人耳对声信号的时频幅特性，尤其是对特殊音色的感知能力，是通常信号处理算法所无法比拟的。应用听觉模型对声信号进行处理，得到声信号的听觉表征，获得具有分类意义的听觉特征，从而提高目标识别系统的分类能力。2.1 试验分析本文应用上述模型对海上实测舰船噪声信号进行了分析。基底膜低通滤波器组设计如图2所示，左图为各通带中心频率对应带宽，右图为部分低通滤波器的频率响应曲线。图2 基底膜低通滤波器组采用101个低通滤波器组，信号采样率为。设舰船噪声信
10、号为，通过上述听觉模型处理后的输出为：；式中C代表被动长波听觉模型处理系统，它代表听神经纤维的放电概率，表征舰船噪声信号的时空分布特性，是低通滤波器通道标号，从小到大对应耳蜗基底膜底部至顶部的不同位置。对大量舰船噪声信号的分析结果表明该听觉模型能很好的表征该舰船噪声的听觉时频幅信息。某舰船噪声的听觉处理输出结果如图3。图 3 某舰船噪声的听觉时空谱2.2 特征分析图3所示的听觉模型输出可看作是一种二维时空分布特征。对其进行分析处理可提取以下几种一维特征。提取时域平均特征：；提取空间域平均特征：；提取短时频域特征：；提取节奏（幅度）特征：；其中为理想低通滤波器，且有成立，该比值应为整数，是舰船噪
11、声信号的降采样率。上述舰船噪声的4种一维特征如图4所示。代表听神经的平均发放率，是人脑对声信号进行感知的基础，可对其进行时间序列分析，挖掘舰船噪声的分类特征；是舰船噪声的听觉空间谱特征，代表舰船噪声的频域特征的听觉感知结果；是的功率谱，是舰船噪声的包络谱。上述4种一维特征从时域、频域和空间域不同的侧面反映听觉特征，是对舰船噪声信号的听觉感知的综合量化描述，反映了噪声信号听觉音色特点。图4 某舰船噪声的4种一维特征3 结论将听觉耳蜗模型应用到对舰船噪声信号的分析中，得到舰船噪声信号能量的时空分布，通过大量海上实测舰船噪声信号的听测分析，能够较全面的反应舰船噪声的听觉特征。4种一维特征能从时频幅多
12、个测面反映听觉分类特征，并较好的与声纳员对舰船噪声的听觉感知相对应。应用听觉模型分析舰船噪声时频幅特征，为被动声纳目标识别提供了新的特征分析方法，同时也为声纳员听音机理的分析打下基础，应用前景广阔。参考文献:1 陶笃纯.舰船噪声节奏的研究(I)一数学模型及功率谱密度J.声学学报,1983,8(2):65-76.2 陈耀明,陶笃纯,杨怡青.舰船辐射噪声线谱的幅度起伏模型J.声学学报,1996,21(4):580-586.3 史广智,胡均川.舰船噪声调制谱谐波族结构特性理论分析,声学学报,2007.32(1):19-25 4 史广智,胡均川.基于舰船噪声仿真模型的目标识别研究,系统仿真学报,200
13、6.18(5):1398-1401 5 被动声呐目标识别技术的现状与展望 ，朱进、章新华，舰船科学技术， 2003,25(5):55-586 陈敬军,陆佶人.被动声纳线谱检测技术综述J.声学技术,2004,23(1):57-60.7 J.G. Lourens.Passive Sonar ML Estimator for Ship Propeller Speed，IEEE JOURNAL OF OCEANIC ENGINEERING, VOL. 23, NO. 4, OCTOBER 19988 J.G. Lourens.Classification of Ships Using Underwat
14、er Radiated Noise IEEE 1988 .p130.9 R.Rajagopal,B.Sankaranarayanan,P.Pamakrishna.Target Classification in a passive sonar An expert system approach, IEEE ICASSP-90,1990,5:2911-2914.10 迟惠生,吴玺宏.听觉计算模型在自动语音识别中的作用,J自然科学进展,2000,10(11) 11 王坚等.听觉科学概论,M中国科学技术出版社,北京,2005,5 P1-512 K. Wang and S. Shamma, Self-
15、Normalization and Noise Robustness in Early Auditory Representations, IEEE Trans. Audio Speech 2(3):421-435, 1994.13 X. Yang, K. Wang, and S. Shamma, Auditory Representations of Acoustic Signals,IEEE Trans. Information Theory 38:824-839, 1992.14 Richard F. Lyon, “A Computational Model of Filtering,
16、Detection, and Compression in the Cochlea”, Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing, Paris, May 1982.Editors note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from torna
17、does to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first satellite - Sputnik. I also missed watching Neil Armstrong step foot on the moon an
18、d the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars
19、.As a meteorologist, Ive still seen many important weather and space events, but right now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.Its like the set for a George Lucas
20、movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I wat
21、ched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a
22、leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partia
23、lly filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappoi
24、ntment on the face of the current record holder and capcom (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays an important role i
25、n this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It
26、 will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The
27、 balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom
28、of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the s
29、peed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachut
30、e that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have
31、a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It
32、 might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.
