低频噪声声品质评价实验研究_英文_

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基于低频噪声检测锂亚电池可靠性的研究

基于低频噪声检测锂亚电池可靠性的研究
WANG Le1∗ ꎬZHANG Penghe2 ꎬCHENG Da2 ꎬLU Chihua1∗ ꎬXIANG Zhibin1 ꎬLI Xianhuai1
(1.Wasion Group LimitedꎬChangsha 410000ꎬChina.2.China Electric Power Research Institute Co.ꎬLtdꎬBeijing 100000ꎬChina)
第6期
14 45
王 乐ꎬ张蓬鹤等:基于低频噪声检测锂亚电池可靠性的研究
放( 存在温度循环及阳光辐射) ꎬ从 2016 年 4 月开
噪声功率谱幅值来衡量低频噪声测试情况[9] ꎮ
容量测试ꎮ
品牌锂亚电池在经过正常条件存放 18 个月后ꎬ频谱
始存放ꎬ持续存放 18 个月后ꎬ进行低频噪声测试和
低频噪声测试设备采用深圳量为科技有限公司
第 42 卷 第 6 期
电 子 器 件
2019 年 12 月
Chinese Journal of Electron Devices
Vol 42 No 6
Dec. 2019
Research on Reliability of Lithium Battery Based on
Low ̄Frequency Noise Measurements
表 1 锂亚电池的低频噪声频谱值
锂亚电池ꎬ又名锂亚硫酰氯电池ꎬ由于其特殊的
化学特性和钝化效应ꎬ其年自放电电流小于 1%ꎬ储
存寿命长
[1-2]
ꎬ 所 以 广 泛 用 于 仪 器 仪 表 中 做 电 源ꎮ
随着锂亚电池的广泛应用ꎬ其可靠性要求也不断提
高ꎮ 目前检测锂亚电池可靠性的好坏ꎬ仍然是通过
常规的环境试验或寿命试验后ꎬ测量性能参数变化

低频噪音消音方法研究报告

低频噪音消音方法研究报告

低频噪音消音方法研究报告一、引言随着我国城市化进程的加快,噪声污染问题日益严重,尤其是低频噪音污染,对人体健康和生活质量造成严重影响。

低频噪音具有传播距离远、穿透力强、难以隔绝等特点,使得传统消音方法效果不佳。

为解决这一问题,本研究聚焦低频噪音消音方法,探讨新型、高效的消音技术。

研究背景的重要性在于提高人们的生活质量,降低低频噪音对人体健康的影响。

本研究围绕以下问题展开:现有低频噪音消音方法的优缺点分析;新型消音技术的研发与应用;消音效果的评价及优化。

研究目的在于提出一种具有实际应用价值、高效可靠的低频噪音消音方法。

研究假设为:通过优化消音材料、结构和工艺,可提高低频噪音的消音效果。

研究范围限定在低频噪音(100Hz以下)的消音技术领域,主要针对室内环境。

本报告将简要概述研究过程、发现、分析及结论,为低频噪音消音技术的发展提供参考。

二、文献综述国内外学者在低频噪音消音领域已开展大量研究。

理论研究方面,已有研究建立了声学理论、振动理论和材料科学等理论框架,为低频噪音消音技术的发展提供了理论基础。

在消音方法上,前人研究主要集中在吸声材料、隔声结构、有源消声等方面,取得了一定的消音效果。

实践中,研究发现,采用新型吸声材料(如开孔泡沫金属、纤维材料等)可提高低频噪音的吸声性能;隔声结构方面,采用双层墙、隔音窗等设计可降低低频噪音的传播。

然而,这些方法在消音效果、适用范围和成本等方面存在一定的局限性。

此外,有源消声技术通过引入反向声波与原声波相互抵消,实现低频噪音消音,但该技术在稳定性、适应性和工程应用方面尚存争议。

当前研究在低频噪音消音方面取得了一定的成果,但仍存在消音效果不足、适用频率范围有限、成本较高等不足。

三、研究方法本研究采用实验方法,结合理论分析和现场测试,探讨低频噪音消音方法的有效性。

以下详细描述研究设计、数据收集、样本选择、数据分析及研究可靠性措施。

1. 研究设计研究分为三个阶段:理论研究、实验设计和现场测试。

低频噪声干扰器效能评估方法研究

低频噪声干扰器效能评估方法研究
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城市变电站噪声的声品质烦躁度评价试验研究

城市变电站噪声的声品质烦躁度评价试验研究

城市变电站噪声的声品质烦躁度评价试验研究陈勇勇;王小鹏;杨威【摘要】针对城市变电站的低频噪声对周边居民影响日趋严重,将声品质评价的概念与研究方法引入对城市变电站噪声的评估中.通过对110 kV、220 kV和500 kV 三座全户内型城市变电站的噪声现场采集,采用等级评分法对变电站噪声的烦躁度品质进行主观试验,计算了所试验的声样本的心理声学参量.通过相关性分析和回归分析,建立了城市变电站噪声的烦躁度品质预测模型.研究结果表明:城市变电站噪声的烦躁度与A声级、响度、粗糙度和抖动度都有着相对较高的相关性,而与尖锐度的相关性较低.烦躁度主观预测模型主要取决于A声级与粗糙度,并且A声级的权重明显高于粗糙度.通过对城市变电站噪声的烦躁度品质进行评价,为变电站噪声的治理提供一个具体的、全新的思路与途径.%Based on the more and more serious influence of low frequency noise of urban substation,the concept and research method of sound quality evaluation were introduced to evaluation of urban substation noise.The whole-indoor urban substation noise for 110 kV,220 kV and 500 kV were collected,and the grading method is used to carried out the subjective test of annoyance quality of the substation noise,and several psychoacoustical parameters are calculated for the tested acoustic samples.The prediction model of annoyance quality of urban substation noise is established by the correlation analysis and regression analysis.The results show that the annoyance of urban substation noise has a relatively high correlation with A sound level,loudness,roughness and fluctuation,but has a low correlation with sharpness.The subjective prediction model of annoyance mainlydepends on A sound level and roughness,and the weight of the A sound level is significantly higher than the roughness.By evaluating the annoyance quality of urban substation noise,it can provide a concrete and new idea and way for the substation noise control.【期刊名称】《科学技术与工程》【年(卷),期】2018(018)013【总页数】5页(P214-218)【关键词】城市变电站;噪声;声品质;烦躁度【作者】陈勇勇;王小鹏;杨威【作者单位】西安交通大学机械工程学院,西安710049;西安交通大学机械工程学院,西安710049;西安交通大学机械工程学院,西安710049【正文语种】中文【中图分类】TB534.1近年来随着城市的快速扩建与发展,越来越多的变电站建在城市居民区与商业区,随之而来的变电站噪声扰民问题也是日益严重。

GaAlAs红外发光二极管低频噪声检测方法

GaAlAs红外发光二极管低频噪声检测方法

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电 子 器

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1 Ga AI As I R ED 的 低 频 噪 声 特 性 与 模 型
G a A 1 A s I R E D的低 频 噪声 通 常表 现 为 1 / 厂 噪声 、
g— r 噪声 、 白噪声 等 的叠 加 , 一般认为 1 噪声 主要 是 由表 面载 流子 数 涨 落引 起 的 。大量 研 究 表 明 , 1
论 依据 。
项 目来源 : 中国地震 局地 震研 究所 基金项 目( 1 S 2 0 1 3 6 0 0 1 ) ; 重庆市高等教育教学改 革研究 重点项 目( 1 3 2 0 1 8 ) 。
收 稿 日期 : 2 o 1 5 — 0 2 — 1 1 修 改 日期 : 2 o 1 5 — 0 3 — 2 8
以G a A 1 A s 双 异 质 结红 外 二 极 管 ( I R E D) 是 一 种
电光 转 换 器件 , 在 一定 的 正 向 电 流 驱 动 下 , 发射 出 峰值波长 8 5 0 n m~8 8 0 n m埃 的 近 红外 光 。该 波 长 适 合 于光 导 纤维在 这 一 频段 ( k = O . 8 m~0 . 9 m) 中 损 耗 低 的要 求 , 有利 于短波长的光纤通信 , 其 可 靠
3 . 中国地震局地震研究所 ( 地震大地测量重点实验 室) , 武汉 4 3 0 0 7 1 ; 4 . 重庆科技学院 电气与信息工程学 院 , 重庆 4 0 2 1 6 0 )
摘 要 : 通过分析G a A 1 A s 红外发光二极管( I R E D ) 的低频噪声产生机理及特性, 建立了G a A 1 A s I R E D 的噪声模型, 设计了一

低频噪音测试标准

低频噪音测试标准

低频噪音测试标准
低频噪音测试一般参考以下标准:
1. 国际电工委员会(IEC)标准:IEC 61400-11-1997 “风能发电场外来声的测量和评估”。

2. 美国环保署(EPA)标准:EPA NSPS(New Source Performance Standards)规定了风电项目在50Hz频率下的最大声级。

3. 欧洲标准:EN 61400-11:2012 “风能发电场外来声的测量和评估”。

这些标准主要包括以下测试内容:
1. 测量位置:测试人员需要在风能发电场周围选择一定数量和位置的测点,以获得全面准确的噪音数据。

2. 测量方法:使用专业的噪音测量仪器进行测量,对风能发电场在不同功率下的运行状态进行测试。

3. 频谱分析:对测得的噪音数据进行频谱分析,以确定低频噪音的分布情况。

4. 噪音评估:经过数据处理和分析,评估风能发电场产生的低频噪音对周围环境和居民的影响程度。

5. 对比分析:将测得的数据与相关的国内外标准进行对比,以确定风能发电场的低频噪音是否符合要求。

需要注意的是,不同国家和地区可能有不同的标准和要求,测试方法和评估指标可能会有所不同。

因此,在进行低频噪音测试时,应参考相应的国家或地区标准。

NTF、ODS、PFP确定车内噪声贡献面板方法

NTF、ODS、PFP确定车内噪声贡献面板方法

NTF、ODS、PFP确定车内噪声贡献面板方法杨磊;邓松;杨双【摘要】首先建立客车结构噪声传递函数模型分析车内噪声峰值频率点。

然后通过工作变形分析函数模型分析在这些噪声峰值频率点车身发生振动变形较大的位置。

将这些振动变形较大的位置设置成噪声贡献面板,建立面板声学贡献量分析模型来确定这些面板对车内噪声水平贡献程度,确定板件对车内声压影响主次关系。

该方法为车内噪声评估和车身面板优化提供有效理论指导。

%The noise transfer function (NTF) model of a bus body was established to evaluate the peak frequencies of the interior noise. Then, the large deformation of the bus body model was analyzed at the peak frequencies of the interior noise based on the theory of the operational deflection shape (ODS). The positions of the large deformation were defined as the noise contribution panels. The acoustic contributions of these panels to the interior noise level were estimated according to the analysis of the participation factor panel (PFP). The results provide valuable guidelines for the determinationof contribution panels of vehicle’s interior noise.【期刊名称】《噪声与振动控制》【年(卷),期】2016(036)002【总页数】4页(P108-111)【关键词】声学;车内噪声;噪声传递函数;工作变形分析;面板声学贡献量【作者】杨磊;邓松;杨双【作者单位】武汉理工大学现代汽车零部件技术湖北省重点实验室,武汉430070; 武汉理工大学汽车零部件技术湖北省协同创新中心,武汉 430070;武汉理工大学现代汽车零部件技术湖北省重点实验室,武汉 430070; 武汉理工大学汽车零部件技术湖北省协同创新中心,武汉 430070;武汉理工大学现代汽车零部件技术湖北省重点实验室,武汉 430070; 武汉理工大学汽车零部件技术湖北省协同创新中心,武汉 430070【正文语种】中文【中图分类】U491.9+1车辆开发前期阶段,运用虚拟技术分析手段来预测车内噪声水平,分析低频、中频和高频内噪产生机理并采取相应预防措施优化车内噪声,避免开发后期进行重复设计和分析,从而达到提高车内声品质和降低成本的目的。

室内低频噪声评价探讨一——A声级与NR曲线的关系

室内低频噪声评价探讨一——A声级与NR曲线的关系

在影响最严重的噪声源发声时进行,测量方法应符合附录二的要求.
注:时使用中不需开窗的建筑.倒如有空讽的宾馆客房,丸许隶声蛀指关富情巩下的修正以度相应的评价曲线的换算
一、因昼夜时间不同,室内允许噪声级的修正.
本规范中的允许噪声级的数值是按白天的要求制 订的,如测量时间与此不符.应接附表3.1进行修正




修正值应符合附表3.2的规定. 注:声级随时问变化较为复杂的噪声,允许噪声报应采 用等效[连续^】声级,等效【连续^】声级的测量,应符 合附录:的要求.
三.噪声级与相应的噪声评价曲线的块算 在隔声设计中有时对噪声的频谱有一定的要求.可 按下式将测得的噪声级换算噪声评价曲线

持续稳定的噪声
态 脉冲性穗态嚎声(划童击.竹接声)
表5.1
项目
著作名称
噪声控制

技术
噪声控制i


交通噪声厦
3●
其控制
有关著作对A声级与NR噪声评价曲线关系的描述
作者名称 出版社名称
车份
对NR.秉声评价曲线的描述
王文奇 江珍泉
张沛商 姜亢
化学工业出 版社
北京经济学 院出版社
1987.10. 199工.7.
…目前广泛应用的田蓐标准化纽织
(IS0)推荐的一族噪声评价曲线(硒称N.曲线 或N曲线).…在通常情况下(^声级大于 55dB)。L^.N,J次+5dB,即噪声评价敏N加上5dB 是与^声级近似相等的.但当^声级小于50dB 时,则N值姜比^声级低10dB左右.
噪声评价曲线号数N值比^声级(L.值)
低5dB左右,对大多数噪声
N-L.一5
1961年,国际标准组织(ISO)第4 3技
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1INTRODUCTIONThecharacterofsoundthatrelatestoaccep-tanceiscalledsoundquality,whichmaywellbe-comealargeroleindeterminingsatisfaction[1].Asaveryactiveandimportantresearcharea,soundqualityevaluationshavebeenappliedintoauto-mobileandelectricappliancesindustryoverlasttwodecades.Bypsychophysicalmeans,soundqual-ityev-aluationandpredictionhasadvancedconsid-erably,butstudiesoflowfrequencynoisearerare.Lowfrequencynoiseisamajorcomponentformanyoccupationalandresidentialnoisewhichhasbehavedascommonbackgroundnoiseinurbanenvironmentbutreceiveslessattention.Theprima-ryperceivedandmostfrequentlyreportedqualitycharacteristicoflowfrequencynoiseisnotthatofloudnessornoisiness,butthatofannoyance[2].How-YANLiang,CHENKe-an(DepartmentofEnvironmentalEngineering,CollegeofMarine,NorthwesternPolytechnicalUniversity,Xi′an710072,China)Abstract:Using75variedlowfrequencynoisesampleswithadjusted-loudnessassoundstimuli,weinvestigatesoundqualityforlowfrequencynoisewithpairedcomparisonmethod.Thejurytestingwithatotalof24jurorshasbeencarriedouttoexploretherelationshipbetweenphysicalpropertiesoflowfrequencynoiseandperceptualratings.Itisshownthattheproposed‘unpleasantness’canbeusedasanreasonableandeffectivemetrictoindicatehuman′sgeneralreactiontolowfrequencynoise,andsomecrucialfactorssuchaslowfrequencycomponentsanditsenergyratios,loudness,temporalandspectralcharacteristics,andsharpnesscouldinfluenceorevengovernthesoundqualityoflowfrequencynoise.Keywords:lowfrequencynoise;soundquality;unpleasantness;pairedcomparison摘要:以等响处理后的75个稳态低频噪声样本为例,采用成对比较法,设计并完成了有24位评价者参与的大规模实验室主观评价实验。

研究发现:1)“不愉悦度”能够充分体现人对低频噪声的主观感受,评价效果理想;2)存在决定低频噪声不愉悦感的频率或频带;响度在决定稳态低频噪声的不愉悦感程度中占主导地位,尖锐度的影响亦不容忽视;与总声能相比,低频段声能比与频谱形状在决定不愉悦程度时,作用更大一些。

关键词:低频噪声;声品质;不愉悦度;成对比较法中图分类号:O42文献标识码:A文章编号:1000-3630(2006)-06-0540-07Jurystudiesofsoundqualityforlowfrequencynoise第25卷第6期2006年12月声学技术TechnicalAcousticsVol.25,No.6Dec.,2006低频噪声声品质评价实验研究闫靓,陈克安(西北工业大学航海学院环境工程系,西安710072)ReceivedAug.31,2006;RevisedOct.30,2006YANLiang:JurystudiesofsoundqualityforlowfrequencynoiseNo.6ever,thedegreeofannoyanceordisturbancegen-eratedbyaspecificnoise,regardlessoffrequency,isdifficulttopredictaccuratelybypracticalmea-surements[3].AlthoughA-weightedsoundlevel(dBA)hasprovenitselfusefulasanapproximatedestimationofannoyanceformediumandhighfrequencysta-tionarynoise,itseverelyunderestimatesannoyanceaswellasloudnesswhenlowfrequencycompo-nentsdominatethenoisespectrum.Bryan[4]foundthatthenoisewithlowfrequencycomponentsandhighsoundlevelgaverisetovigorouscomplaintseventhoughtheexposurelevelwasonlyaround55dBA.Tempest[5]foundthatthenumberofcomplaintswerefarlargerthanthatpredictedfromA-weightedsoundpressure.PerssonandBjo"rkman[6]comparedfourbroadbandfannoisescenteredat80,250,500,and1000Hz,andfoundthatthenoisecenteredat80HzwasperceivedtobesignificantlyannoyingthantheothernoiseswiththesameA-weightedlevels.Takingadvantageofthepsychophysicalmag-nitudeestimationtechnique,BronerandLevebthall[7]foundthattheB-weightedsoundlevelisthemostsuitablemeasureinpredictingtheannoyanceduetohigherlevel(90 ̄105overallSPL)forlowfre-quencynoise.However,itremainsaquestionwhe-therasimilarconclusionisvalidforlow-levelandlowfrequencynoise.Moreover,insufficientmeasurementandcontrolofthefrequencyrangeandharmonicsmaybeiden-tifiedaspotentialproblemsinbothfieldrecordingsandexperimentalgenerationoflowfrequencynoise[8].Theearlieststudiesemployedexposurelevelswhichwouldalmostcertainlynotbeallowedtoday.InDenmarkasetofguidelinesformeasurementandassessmentofenvironmentallowfrequencynoise,infrasoundandvibrationwerepublishedin1997[9].Hence,itisveryimportanttoestablishama-thematicalmodelforpredictingthesoundqualityforlowfrequency.Thispaperdescribeslaboratorystudiesabouttheinfluenceoftheinterferencecausedbyseveralcommonlowfrequencynoisesonsoundquality.Tomeasurethequalityoflowfre-quencynoise,thepairedcomparisonmethodisusedinjurytestingwithatotalof24jurorstoexploretherelationshipbetweenphysicalpropertiesoflowfrequencynoiseandperceptualratings.Ameasurableperceivedquantitynamed“unpleasantness”andthecorrespondingscalesareproposed.Basedonthejurytests,anempiricalunpleasantnesspredictivemod-elisobtained,whichgivesaquantitativeappraisalofsubjectiveresponsetolowfrequencynoiseini-tially.2LOWFREQUENCYNOISEQUA-LITYANDUNPLEASANTNESSNumerousresearcheshaveindicatedthatthenoisequalityisnotdescribedsufficientlybyaone-dimensionalmeasure.Themulti-dimensionalcharac-terofbothacousticandhumanperceptualresponsecanbestudiedbyquestionnaireaboutsoundquali-tydescriptors,factoranalysisandclusteranalysis.Then,twofundamentaljurytestsnamelypairedcom-parisonandsemanticdifferentialsareoftenadoptedtodealwiththemulti-sensorydimensionsinsoundquality[1].Ontheanalogywiththeexistedsoundqualitydescriptor“annoyance”,theauthorshavepresentedanewmetric,namedunpleasantness(expressedas‘up’),whichcanindicatetheactualfeelingsofhu-manbeingsforlowfrequencynoiseenvironments,andismoresuitableforlaboratorialresearch.Theauthorshavepointedoutthatthe‘unpleasantness’canindicatethelowfrequencynoisequalitymoreveritably[10],whichisdividedinto5degreeranks[11],namely‘notatall’,‘slight’,‘moderately’,‘very’and‘extremely’.Wethinkitseemsagoodchoicetousethe‘up’asanobjectiveestimatorforlowfrequencynoisequalitybecauseitsapplicablecon-ditionsandscopesaremoreexplicit,anditcanbemoresuitabletoaddresstheemotionalresponsetolowfrequency′sinterference.Itisassumedthattherearemsubjectsran-541TechnicalAcoustics2006domlyselectedtotakepartinasetofjurytests,nofthemgiveranksupwardsof‘moderately’(in-cluding‘moderately’),andthentheupcanbecalculatedasfollow,up=nm×100%(m≥20)(1)Theoreticallyspeaking,thenumbersofsubjectsinthejurytestcanbedecidedbytheaccuracyanddistributionofthetestresults,however,onlytheempiricalapproachcanbeusedtoensurehowmanysubjectsshouldtakepartinthejurytest.In1999,bycomparativeanalysis,HempelandCho-uardfoundthatnodistinctdiversityexistedbetweenthe54-subjectsandthe20-subjectsjurytest[12]andboththeaveragevaluesandthestandarddeviationsofthemwerenearlyconsistent.Thentheyproposedthatformostpsychoacousticstudies,20-subjectswereenough.Followingthis,inthepre-sentstudyism≥20used.3PAIREDCOMPARISONBASEDJURYTESTINGJurytestingisanessentialstepinsoundqualityevaluation[13].Atpresent,thecommonlyusedsubjectiveassessmentmethodsmainlyincludemak-ingscores,rankingorders,pairedcomparisonandsemanticdifferentials[14].Ingeneral,fordifferenttestingtasks,correspondingmethodsshouldbeap-pliedtoachievegoodperformances.Inthisstudy,pairedcomparisonbasedonjurytestisselectedtocharacterizethelowfrequencynoisequality.3.1RecordingofnoisesamplesLowfrequencynoisesamplesfromcarinterior,ventilationsystemsandtransformersincommunitywererespectivelyrecordedbyaBSWAVS302USBSpectraPlusdualchannelspectrumanalyzerequi-ppedwithaB&KType2230integratingsoundlevelmeter.Afterreal-timespectralanalysis,recording,playbackandpost-processingareaccomplished,9effectiveappraisalsampleswereobtained.Then100stablesamplesweredownloadedfromInternet,whichhaveobviouslowfrequencycharacteristicsandorientedfromvariousvehicles,machinesandequipmentsunderdifferentoperationsituationsaswellasnaturalsounds.Theoreticallyspeaking,largenumbersofsamplescanensuretheresults′reliabilityandaccuracy,butleadtoenormousworkloadandovertimeexper-iments,evencausehearingfatigueandaffecttheappraisalresultsultimately.Thus,60optimalsam-plesareselectedfromvarioustypesoflowfrequencynoise,fromwhichwecouldfindoutthesubjectiveresponserulesandestablishaprelimi-narysensationmodel.Beforetheformaljurytest,allsamplesarepre-treatedasfollows:(1)Removetheunstablesamplesandlengthin-terceptionisdonetopreservetypicallowfrequencycharacters.Allsampleshavethesametemporaldi-mension,10secondsforplaying.(2)Equalizethesoundlevelofeverysample,andmakesurethatthesoundleveldifferencesbetw-eeneveryevaluatingspotaresmallerthan3dBA.(3)Matchthedefinedfrequencyrange(lowerlimits5,10,16,20,50Hz,andupperlimits100,150,200,250,500,600Hz)inpairsran-domly,andthencalculatethecorrespondinglowfre-quencyenergyandlowfrequencyenergyratio,re-spectively.3.2SubjectsTwentyfoursubjects,12malesand12femaleswhohaveanaverageageof23yearsfrom18to27,tookpartinthejurytest.Theywereeitheru-niversitystafforpostgraduatewhosemajorsarea-cousticsorenvironmentalscience,allofwhomhadnormalhearing.Facingterminalloudspeaker,thesubjectswereseatedatevaluatingspotsdistributingatasemicir-clewitharadiusof3minthelaboratory.Priortotheformaltests,threepre-trainingphaseswerecarriedoutforthesubjects:gettingknowledgeaboutnoisesamples,explainingmeaningofsoundqualitymetrics,anddescribingjudgmenttacticsandcon-542YANLiang:JurystudiesofsoundqualityforlowfrequencynoiseNo.6versation.Finally,everysubjectwasaskedtorec-ollecttheirfeelingsandtogiveadvicesforthetests.Dependingonthese,wecouldawarethesubjects′comprehensiveextentoftheChineseadjectivedescribinglowfrequencynoisequalitymetric-un-pleasantness.3.3MethodAnimportantaspectofpairedcomparisonwithforcedchoiceisthedecisionofhowtoformpairsinadvance.Inourtest,thetotalof75sampleswasdividedintotwosets,15recordingsamplesinoneand60optimalsamplesintheother,whichadopttwodifferentpairingdesigns,respectively.Eachcou-pledsetispresentedtothesubjectswhowerein-structedtodecidehispreferenceeachtime,byans-weringquestionssuchas:′choosewhichoneismoreunpleasant′.3.3.115samplespairingdesignAccordingtotraditionalcompletedesigns,15effectiveindependentsamplesarepairedrandomlywithnorestrictionsonpairings.Then,asequenceof255couples,including15i-icomparisonsand105j-icomparisons,isformed.Inordertomini-mizeordereffects,thesecoupleswerepresentedinatotallyrandomorderforeachsubject.Eachcouplewaspresentedfor25s(20splaybackduration,5sintervalforevaluating).Consideringadverseeffectsandfatiguecausedbylowfrequencynoise,wedi-videdallsamplepairsintotwogroups.Themeantestingdurationforeachgroupwas30min.with1hbreak.3.3.260optimalsamplespairingdesignThecompletepairingdesignwouldresultinanoveralltestsessionwith25hoursforeachsubjectindividually.Nevertheless,asanempiricalrule,everysessioninthejurytestshouldbeperformedwithin20 ̄30min,notmorethan45min.Andtheintervaltimebetweeneverytwosessionsshouldbenotlessthan30min.Therefore,theincompletepairingdesignwhichthesamesamplepairs(i-i)andtheinvertorderpairs(j-i)werenotdemandedwasemployedtofulfilltheaboverequirements.Concerningvalidity,20j-ipairsand10i-ipairswereselectedandaddedtothesequencerandom-ly,resultinginatotalof1800pairswhichissep-aratedinto30groups.Thesubjectscarriedoutthistaskon3separateddays.3.4AnalysisThetestingdatawereanalyzedwiththeSPSSsoftwareasfollows:1)accordingtotheobtainedre-ferencescaledescribedinsection2,measurableattributesoflowfrequencynoisequalityaretranslatedintothecorrespondingnumericalvalues;2)forthesubjectivedataprocessing,i-iandij-jierrorrateanalysis,normaldistributiontests,rankscaleanalysisaresuccessfullyadopted;3)forallsam-ples,thecorrelationofthemeanopinionscoreda-taand3calculatedpsychoacousticparametersareanalyzed;and4)withtheaidofprincipalcompo-nentsanalysisandmultiplelinearregressionanalysis,anempiricalunpleasantnesspredictivemodelforlowfrequencynoiseisobtainedasfollows.UP=0.834N+0.156R+0.041S(2)whereN,RandSarerespectivelytheloudness,roughnessandsharpnessandcanbecalculatedbyZwicker′smodel[14],andUPisthemeanvalueoftheunpleasantnessopinionscoresfromeachsubject.Thismodelshowsanearlyperfectperformance(thegoodnessoffitisabout96%,thestandarderrorisabout95%)inthepredictionofthemeanopinionscoredataofvariouslowfrequencynoisesamples.4RESULTSANDDISCUSSIONSCombiningtheunpleasantnessdoes-responsecurvesandcauseanalysisforlowfrequencypuretones[8],wehavefollowingresults:(1)Considerablevariationsofunpleasantnessaswellasroughnessandsharpnesscanbeobservedbecauseofthedifferencesoftheamplitudeoflowfrequencycomponentsbeforeandafterloudnessen-hancement.(2)Adirectproportionalrelationshipbetweensharpnessandroughnesscanbegiven.Itiscon-543TechnicalAcoustics2006cludedthatloudnessisadominantfeatureforanysoundqualityevaluation,canalsogivesoundintensityinformationaboutthelowfrequencycontentofnoisesamples.Loudnessenhancementcanin-ducesmallermaskingbyhighfrequencycontentinthesampleitselforinthebackgroundnoise,andthenroughnesstendstoincreaseduetothecorre-spondingenhancementofthelowfrequencycom-ponents.Oppositely,forthesharpnessofnoisesam-plesthetendencyistodecrease.(3)Formostsamples,unpleasantnessdecreaseswiththeincreaseofroughnessandsharpness.ThisresultdemonstratesthatunpleasantnessfromlowfrequencynoiseismuchhigherthanthatfromnoisewithoutdominatinglowfrequencycomponentsatthesamedBAlevel.Whereasthereisanoppo-siterelationshipfortherecordingsamples.Thisdiscrepancyisprobablyduetotheaffectedlowfrequencycomponentsundertheactualsettings,thelowfrequencyresponseandfidelityoftherecordingandreplayingequipments,andsoon.(4)TakingM1=-0.835N+0.681R+0.550SandM2=0.024N-0.597R+0.776Sasprincipal-components,amodelconsistedofF1=0.571N-0.465R-0.376SandF2=0.025N-0.623R+0.809Scanbeimplemented.Thisoutcomeshowsthatthedescriptor′unpleasan-tness′isatwodimensionalquantity,andtherearetwodifferentkindofjudgmenttendencyofsubjects.Thefirstdimensionofunpleasantnesshasapositiverelationwithloudnessaswellasanegativerelationwithbothofroughnessandsharpness.But,thesec-onddimensionofunpleasantnesshasapositiverelationwithsharpnesswhichisstrongerthanitsnegativerelationwithroughness,moreover,itsposi-tiverelationwithloudnessbecomesinconspicuous.Inspiteofanattributeofsignificantspectralcom-ponentsathighfrequencies,sharpnesscanaffectthelowfrequencynoisequalityduetoambiguousmechanism.(5)Figure1givesthepowerspectraofthesample13,14,and4usedinthejurytests.Table1shows30lowfrequencyenergyratios.Therankingnumberbasedonthemeanunpleasantnessscoreofeachmeasurednoisesindicatesthatthesample13isthemostunpleasant,thenisthesample14,foll-owedwiththesample4.ItseemsthatlowfrequencyTable130lowfrequencyenergyratiosofthesample13,14,3Lowfrequencyregion(Hz)5 ̄1005 ̄1505 ̄2005 ̄2505 ̄5005 ̄600EnergyRatio%137.22957.25697.26297.26887.27277.2731146.85496.86456.86706.86816.87036.870547.62987.65237.65657.65927.66557.6667Lowfrequencyregion(Hz)10 ̄10010 ̄15010 ̄20010 ̄25010 ̄50010 ̄600EnergyRatio%134.025014.05264.05864.06444.06844.0687143.47683.48643.48893.49003.49223.492442.96512.98772.99182.99463.00093.0021Lowfrequencyregion(Hz)16 ̄10016 ̄15016 ̄20016 ̄25016 ̄50016 ̄600EnergyRatio%132.22612.25362.25962.26542.26942.2697141.48491.49461.49711.49811.50031.500541.26261.28521.28941.29211.29841.2996Lowfrequencyregion(Hz)20 ̄10020 ̄15020 ̄20020 ̄25020 ̄50020 ̄600EnergyRatio%131.62791.65541.66141.66721.67121.6715140.823390.83300.83550.836550.838750.8389540.812180.83470.838890.841590.847980.84913Lowfrequencyregion(Hz)50 ̄10050 ̄15050 ̄20050 ̄25050 ̄50050 ̄600EnergyRatio%131.62791.65541.66141.66721.67121.6715140.098630.108240.110730.111780.113980.1141940.0528260.0753470.0795320.0822360.0886220.089772544YANLiang:JurystudiesofsoundqualityforlowfrequencynoiseNo.6Frequency/HzFrequency/HzFrequency/HzFig.1Powerspectraofthesample13,14,and402004006008001000120014001600180020002000-2002000-2001000-100Powerspectrumofsample13(a)Powerspectrumofsample14(c)Powerspectrumofsample14(b)noisequalitywouldbeinfluencedbynotonlytheentiresoundenergybutalsothetemporalenvelope,spectralshapeandlowfrequencyenergyratio.(6)Unpleasantnessratingbasedonthejurytestresultsdiffersfromthatontheentirenoiseenergy,whichmaybeduetothefactthatdBAisnotthebestestimatorforlowfrequencynoisequality.Becauseofmaskingbyhighfrequencycom-ponentsinactualandexperimentalsettings,repla-yinglevelsaremuchlargerthanrecordinglevelsespeciallyfortherecordingsamples.Thereforelou-dnessequalizationshouldbepreferred.Someunce-rtaindisturbingfactorssuchasequipmentsperfor-manceandexperimentconditionsmustbeconsi-dered.(7)Atverylowfrequencyhuman′sauditorysystemhasnotresponseinthenormalsense,andthecommonacousticalmetricsareuselessinde-scribingperceptible.However,thesubjectivereac-tionssuchasunpleasantnessariseandunpleasant-nessmaycontributeincomplicatedways.Thepre-sentjurystudiesindicatethat,generally,theob-servableunpleasantnoisespossessprominentlowfrequencycomponentsintherangeof5 ̄20Hz.Itisobviousthatthelowerlimitoflowfrequencynoiseat20Hzisnotsuitableandfurtherstudiesneedtobeperformed.5CONCLUSIONSItisshownfromthisstudythatunpleasantnessisanalternativedescriptoroflowfrequencynoisequalityandissimpleandfeasibleforthelaboratoryinvestigation.Asatwodimensionalperceivedquan-tity,unpleasantnesscangivereliableandrepresen-tativeresultstorepresenttypicallowfrequencynoiseexperiencedbytheoccupants.Thereportedunpleasantnessmodelforlowfrequencynoisequali-tyisareasonablypredictoroftherespectivejurytestresults(GoodnessofFit=0.96).Loudnessplaysadominatingroleinshapingperceptionsoflowfrequencynoisequality,furthermore,somecruciallowfrequencycomponentsanditsenergyratios,temporalandspectralcharacteristics,sharpnessco-uldinfluenceorevengovernthesoundqualityoflowfrequencynoise.Inspiteofthefactthattheproposedestimatorisinitiallydevelopedforveryfewkindsoflowfrequencynoise,theresultsob-tainedforotherstablenoisescouldalsobemean-ingful,especiallyforlowfrequencynoisessimilartothetestingsamples.ACKNOWLEDGMENTSThisworkisapartofaprojectNo.10574104supportedbyNSFC(NaturalScienceFoundationofChina).Theauthorsaregratefultotheexperimen-talfellows.REFERENCES[1]UJekosch.Meaninginthecontextofsoundqualityas-sessment[J].ActaAustica,1999,85(5):681-684.[2]NBroner.Theeffectsoflowfrequencynoiseonpeo-ple-areview[J].JournalofSoundandVibration,1978,58:483-500.[3]CMHaslegrave.AuditoryEnvironmentandNoiseAs-sessment.EvaluationofHumanWork[M].editedbyJ.Powerlevel(dB)Powerlevel(dB)Powerlevel(dB)02004006008001000120014001600180020000200400600800100012001400160018002000545TechnicalAcoustics2006R.WilsonandN.Corlett.,London:Taylro&Francis.1990.406-439.[4]MEBryan.LowFrequencyNoiseAnnoyance.Infra-soundandLowFrequencyVibration[M].editedbyW.Tempest,London.Academic.1976.65-69.[5]WTempest.LoudnessandAnnoyanceduetoLowFre-quencySound[J].Acustica,1973,29:200-205[6]K.Persson,M.Bjo"rkman.Loudness,AnnoyanceanddBAinEvaluatingLowFrequencyNoise[J].JournalofLowFrequencyNoiseandVibration.1990,9:32-45.[7]NBroner,HGLevebthall.ACriterionforPredictingtheAnnoyanceduetoHigherLevel,LowFrequencyNo-ise[J].JournalofSoundandVibration.1982.84(3):443-448.[8]BBerglund,PHassmén.SourcesandEffectsofLowfrequencyNoise[J].JournaloftheAcousticalSocietyofAmerica.1996.99(5):2985-3002.[9]JJakobsen.DanishGuidelinesonEnvironmentalLowFrequencyNoise,InfrasoundandVibration[J].JournalofLowFrequencyNoise,VibrationandActiveControl,2001,2(3):141-148.[10]YANLiang,CHENKean.SubjectiveEvaluateonUn-pleasantnessofLowfrequencyPureTone[J].ChineseAppliedAcoustics,2006,25(5):319-324.[11]DBotteldooren,AVerkeyn,AFuzzyrulebasedfra-meworkfornoiseannoyancemodeling[J].JournaloftheAcousticalSocietyofAmerica,2003,14(3):1487-1498.[12]YANLiang.ObjectiveEvaluationofSubjectiveReactiontoLowfrequencyNoise[D].Master′sDegreeThesis,NorthwesternPolytechnicalUniversity,2006.[13]B.R.Giovanni,F.Crenna,M.Codda.MeasurementofQuantitiesDependinguponPerceptionbyJury-TestMethods[J].Measurement,2003,34:57-66.[14]H.Fastl.Thepsychoacousticsofsound-qualityevalua-tion[J].ActaAcustica,1997,83(3):754-764.2006年10月20日中国声学学会第六届全国会员代表大会期间,检测声学分会在李明轩主任召集下召开分会委员座谈会,就检测分会近来的工作及下一年的活动进行讨论。

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