ATP 08 - now available! - HEAD acoustics · PDF fileReal-timeFFTanalysis Available analyses: time, ... Easy-to-use, configurable sen- ... noise to your ear (airborne sound transfer

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HEAD No. 17 May 2004lines

An update of the first version ofSQuare introduced last year willsoon be available with many newfeatures. The new version ex-pands the range of possibleapplications and makes the sys-tem even easier to use. In addi-tion to the well-known functionsof the first version, SQuare 2.0features the following:

Judgement during playback,and interruption and continu-ation of the listening test se-quence. This allows the test

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leader, for example, to removeindividual subjects from thetest, while the test can becontinued with the remainingsubjects.Optional joining of test resultsfrom several successive testsessions with different parti-cipants.New test types, e.g. a rankingtest, where a number of soundexamples is to be sorted in acertain order based on a pre-defined attribute.

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Channel selection for multi-channel files during import.This is one of the new featuresof the Import Wizard.Convenient configuration andediting of tests in the PlaylistDesigner.

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Enhanced layout of the inputinterface and simultaneousdisplay of the test criteria onthe listening station PC.Many other new features.

NEW: SQuare Version 2.0 - Jury Testing and Evaluation System

further processing in ArtemiS.

Real-time FFT analysisAvailable analyses: time, FFT,FFT vs. time, auto- & cross-spectrum, auto- & cross-corre-lation, frequency & impulse re-sponse, cepstrum, octave &1/3-octave spectrum, cohe-rence, liftered spectrum, soundintensityMobile real-time diagnosticsStructure examinationEasy-to-use, configurable sen-sor listClear display of diagrams,functions and controls in oneinterface

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Features

The new Online Analysis Module for ArtemiS for Signal andSystem Analysis in Real-Time Mode

The new Online Analysis Moduleprovides ArtemiS users with atool that excels with its power aswell as its clear structure andease of use. Diagram windowsand key controls are united inone integrated user interface,providing all of the important

information at a glance.All functions can be controlledvia the keyboard, making itpossible to use the analyzer forapplications where mouse oper-ation is not practical; e.g. on-road vehicle diagnostics.Analyzer results may be saved for

ATP 08 - now available!

Vibrating Surfaces made audibleUsing Laser Scanning Vibrometry and Binaural Transfer Path Analysis

ponent is not enough to describethe acoustical situation sufficiently;the degree of the sound pro-jection, the transmission of thenoise to your ear (airborne soundtransfer function) and the time-frequency structure of the noise(important for the psychoacousticeffect on a person) must be con-sidered. Consequently, a success-ful reduction of the component'sphysical vibration may not reducethe audible impact of the noise onthe listener. Thus, the questionspersist: “Which vibrations aregenerating the offending noise? Atwhat location should counter-measures be applied?”A joint project between Polytec andHEAD acoustics aims to answer

Acoustics are increasingly impor-tant in product design. The focusis on how and where the unde-sired noises are generated and atwhich point or location coun-termeasures can be applied toeliminate or attenuate the offen-ding noise. Knowing just the vi-bration characteristics of a com-

these questions and to make aconnection between vibrationanalysis and the generated noise.The expertise of Polytec in mattersof laser vibrometry and vibrationanalysis and the expertise of HEADacoustics with regards to auraliza-tion of sound sources complementeach other perfectly. Their aim is todevelop a tool which can beapplied to aural acoustic prob-lems in an efficient and preciseway.

Starting with a vibrating surface,the projected sound is transmittedthrough the air and finally reachesthe human subject's ear in the formof noise. With the aid of transfer

The New Test Procedure

Explanation of the photo above: Within the framework of these investigations, the process was tested using a model structure which can be seen in the photoabove. The model consists of a steel frame on which metal surfaces of different sizes have been mounted. Two shakers introduce vibration. The experimentallydetermined transfer paths describe the sound propagation from the position of force application at the shakers to the ears of the test person located inside themodel. As is shown the test person is represented by an artificial head or binaural velocity transmitter. The determined transfer paths can, in principle, beassociated with any time signal data, e.g. the force transmission points of an engine mount of a car.

What kind of noise is gene-rated when the surface of acomponent vibrates? Whatpath does the noise take toarrive at your ear? Whichcomponent's vibration is themost undesirable? These arethe questions that the engin-eers at Polytec and HEADacoustics are working to solvein a joint project.

May 2004 Page 2

path analysis the path of the soundcan be determined experimentally.As an extension of the processHEAD acoustics determines theairborne sound paths binaurally.Thus, the shape of the head isincluded in the analysis, makingthe auralization of componentsound sources possible. How,

do you determine thetransfer functions for airbornesound binaurally? For this purposeyou can resort to the reciprocityprinciple and measure the airbor-ne sound transfer paths reciprocal-ly with the aid of a binaural soundtransmitter (see explanation in theInfo Box).This new process allows you to linklaser vibrometer measurementswith reciprocal airborne soundmeasurements. For visual repre-sentation of the component vibra-tion, instead of using the vibrationamplitude measured directly withthe laser vibrometer, the amplitudeweighted with the reciprocallymeasured transfer function forairborne sound is given. This re-presentation is a measure of theairborne sound relevance of thecomponent's surface and showswhether and to what extent singleareas are responsible for the noisereaching your ear. The locations atwhich acoustic measures need tobe introduced are, in turn, clearlyvisible for the acoustic engineer.User Defined Data Sets are the

practically,

technical basis for linking thestructure-borne data with thetransfer path functions. They areavailable as a new option in thePolytec PSV Software release 8.1.Extensions to this software optionare being planned and shouldmake it possible to view non-stationary events as well. This maybe particularly interesting for theautomobile industry in order toanswer questions with regard toengine noise such as: “At whatengine speed and at whichcomponent surface is the sourcefor the noise located?” This isattained by visualizing filteredtime sequences using acoustictransfer functions. An appropriatesoftware option is currently underdevelopment and will be avail-able shortly for Alpha testing.

For more information and a PDFcopy of this article, please visitPolytec's web page at:

or the homepage of HEADacoustics at:

.

www.polytec.com

www.head-acoustics.de

The Reciprocity Principle

The transfer function betweensound source and receivinglocation does not change if thesound source and receivinglocation are exchanged. Thisapplies subject to the conditionthata) the emission characteristics ofthe transmitter are the same as thereceiving characteristics of thereceiver andb) only linear systems and quantitypairsare taken into consideration, e.g.acoustic pressure and volumeflow. Therefore, if the receiver is ahuman head, then the soundtransmitter must also be in theshape of a human head. Apartfrom that, it is imperative to knowthe volume flow emitted by thesound transmitter. If these condi-tions are fulfilled, then reciprocityapplies in all environments, inde-pendent of the spatial properties.

Page 3 May 2004

Noise emissions of products arean important quality indicatornot only in the automotive indus-try. In many industries noise re-duction is an important issue inthe product developmentprocess.

Until now, the development,purchase and application ofsimulation programs suitable foranalyzing, reducing or changingnoise emissions required asubstantial financial investment.Realizing that such oiseynthesis echnologies (NST) for

systematic product noise reduc-tion should also be madeavailable to industries whosemanufacturing processes do notallow such costly efforts, theEuropean research projectNABUCCO ( oise atement

sing oncurrent omponent-Product ptimisation) wasestablished in 1999. The goal ofthe project was to achieve anacoustic product optimization byidentifying and then simulatingpartial structures and sound

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N AB

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technology and can be used bymany manufacturers for soundoptimization. PRONS supportsthe creation of a NST model,which allows a simulation of thesounds generated by a product,even before the first prototype isproduced. Individual noisesources can be easily exchangedwith others in the model. Usingthis “virtual device”, the noiseemissions can be judged withoutever touching a single screw ormaking expensive measure-ments. Time- and cost-intensivereal-life tests can thus be reduc-ed to a minimum. Applicationexamples include refrigerators,lawn mowers, or power tools.Noise synthesis technology isbased on sound and vibration

PRONS 2.0 - a Software for the Simulation of Home Applicance Noise

measurements of individualnoise sources such as com-pressors, fans, or motors and, atthe same time considers theproperties of the total structure.Once these input data have beendetermined, PRONS starts thesound synthesis and is capable ofsimulating the sound perceivedat any location in the environ-ment

Figure 1 shows a model genera-ted with PRONS. The modelconsiders all three sound transferpaths: airborne sound (com-pressor), structure-borne sound(suction line and return line) andfluid-borne sound (return line).

Figure 1: Simulation example “Refrigerator”, displayed with PRONS.Right diagram: PRONS user interfaceLeft diagram: The three transfer paths in the total structure (AB: airborne, SB: structure-borne, FB: fluid-borne)

RefrigeratorFB ( 0.00-10.00 s).FL/dB[SPL]

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30

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f/Hz20 50 500 1000

AB

SB

FB

Structure-borne CSS

Fluid-borne CSS

Airborne CSS Airborne ACF

Strucure-borne

ACF

Fluid-borne

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Refrigerator

transfer paths of a pro-duct.

One result of this re-search project is thePRONS software. TheProduct Noise Synthesizeris a tool that incorporatesstate-of-the-art computer

May 2004 Page 4

Page 5 May 2004

Since its establishment morethan three years ago, theTraining has become aninherent part of the extensiverange of services offered byHEAD acoustics. It enjoys greatpopularity among our custo-mers. Concerning the planningof the seminars' contents and thetypes of workshops offered, theneeds of our customers arealways the most important factor.

The extensive range of coursesoffered by the Training isaddressed to beginners as wellas advanced users of ourproducts. They range from anintroduction to the basics of dataacquisition to product trainings(e.g. ArtemiS, NoiseBook) and tospecific areas like psychoacou-stics or digital signal and systemanalysis. Besides impartingtheoretical knowledge, the mainfocus is on a wide range of real-life, practical exercises. Toperform these exercises, eachparticipant is provided with up-to-date technical resources.Thus, we guarantee efficientlearning with lasting success.

Users ofour NVH products will meet toexchange their experiences.Each meeting will feature apreviously defined topic, whichwill be explained based onpractical applications. Possiblesolutions will be illustrated stepby step. The first workshop inJune will focus on the topic

Center

Center

In 2004 we will organize for the first

time a NVH User Group.

New offerings of the Trai-ningCenter

All courses are available inEnglish.See our web site for detailsabout these and other offeringsand contents, or contact us at

, or atfor our

US customers.

[email protected]@headcoustics.com

“Correction of recorded mea-surement data”.This year's range of trainingofferings will also be comple-mented by a NoiseBook Advan-ced Training, which is recom-mended subsequently to thestandard NoiseBook Training.

The HEAD acoustics TrainingCenter

English courses offered …

… at HEAD acoustics GmbH, Herzogenrath, GermanyMay 18 & Nov 11 Signal AnalysisSep 28-29 ArtemiSSep 30-Oct 1 ArtemiS AdvancedOct 5-6 Visual Basics for ApplicationsOct 7-8 ArtemiS COM InterfaceOct 12 Data AcquisitionOct 13 Binaural Measurement TechniqueOct 14 Psychoacoustics

… at HEAD acoustics Inc., Brighton, MI, USAJun 1-2 & Sep 14-15 ArtemiSJun 3 & Sep 27 ArtemiS ClinicJun 8-11 ArtemiS COM CourseSep 16. HEAD Measurement System TrainingSep 16 SQlab II SeminarSep 27 NoiseBook SeminarSep 28-29 ArtemiS IISep 30-Oct 1 ArtemiS III

for eight-channel vibrationmeasurements for the calcula-tion of (complex) transfer func-tions as well as coherence func-tions between different vibrationchannels.

as the basis for their sound andvibration analysis was based onthe advantages of ArtemiS. Thesoftware allows VW the followingbenefits:1. Record time signals andsubsequently perform additionalanalysis functions besides thestandard measurements.2. Adapt results to the custom-ized software package, called“Akustiksystem”, for the evalua-tion and consistent graphicalrepresentation of data. The“Akustiksystem” was custom-de-signed by VW, is constantly up-dated and is being used by theacoustics departments of thecompany, its subsidiaries, and itsworld-wide production facilities.3. Program and automate re-cordings and analysis proce-dures via the COM interface.Thanks to its ease of use, this caneven be done during test drivesby a measurement technician ora test driver.The modular design of theSQlab II hardware also had amajor influence on VW's deci-sion to choose the products ofHEAD acoustics. For example,the two- to six-channel inputmodules of SQlab II allow a widevariety of different signal types tobe recorded. Furthermore,measurements can be immedia-

The decision of VW to usesystems from HEAD acoustics

In this issue of the HEAD wewould like to present the long-term customer relationship be-tween our company and Volks-wagen AG (VW) of Wolfsburg,Germany.Since 1987 HEAD acoustics andthe car manufacturer have beenin close contact with each other.For sound measurements, VWoriginally used the HMS I artifi-cial head and BAS software, theDOS-based predecessor ofArtemiS.In order to meet the increasingdemands of customers regar-ding the acoustic quality of theirvehicles, VW established the“Vehicle Acoustics Department”in 2001 with a large AcousticsCenter, where experts focusexclusively on the acoustic opti-mization of vehicles.Today the Vehicle AcousticsDepartment is equipped with atotal of 25 ArtemiS licenses: 14

lines

Sound and Vibration Analysis at Volkswagen - A Standard inThe Vehicle Acoustics Department with 25 ArtemiS Licenses

VW Phaeton on the exterior noise dynamometer

of them are network licenses foroffice-based applications likeanalysis, data evaluation, dataexport etc. The other 11 licensesare used in combination with 11lab-based SQlab II systems, themobile multi-channel measure-ment sys tem from HEADacoustics.The Vehicle Acoustics Depart-ment uses four license variants ofthe ArtemiS software. Dependingon the desired analysis type, theuser can freely select any of theselicense variants by using a net-work dongle.The SQlabs are mainly used forpure data acquisition and somebasic analysis functions. The ex-ceptions are two special SQlab IIsystems: one is known as the“Shaker Measurement Chain” foracoustic and vibration-relatedidle-running measurements on atest bench or chassis dynamome-ter. The other one is a system used

May 2004 Page 6

and driving performance, signi-ficantly influence the comfortimpression of a vehicle, theseinvestments were indispensablefor establishing a strong founda-tion to further improve thesecharacteristics.The Acoustics Center is equip-ped with several chassis dyna-mometers using state-of-the-artmeasurement technology. Theyare used for pass-by noise re-search and source analysis.Sound and vibration analyses upto a maximum speed of 300km/h (186 mph) can beperformed with ArtemiS andSQlab II.The ongoing communicationbetween VW and HEADacoustics GmbH is an importantaspect of this successful relation-ship. Problems are attended toimmediately by both sides, andthanks to our sales and internalcustomer service experts, solu-tions are quickly provided.We look forward to a suc-cessful continuation of ourclose collaboration.

tely checked, analyzed andlistened to on-site. In addition,the CHG 20 modules supportthe connection of force andacceleration sensors, elimina-ting the need to carry alongseparate charge amplifiers.Furthermore, more modules canbe added at any time withoutincurring additional softwarecosts: all modules are detectedautomatically and displayed onthe screen. Channel lists can besaved separately and retrievedat any time. The systems are thusextremely easy to operate and,thanks to ArtemiS, easy toconfigure as well.The combination of the analysissoftware ArtemiS and theanalysis measurement systemSQlab II is a tailor-made solu-tion for all kinds of sound andvibration analysis at VolkswagenAG.

The same high standard thatapplies to the hardware and soft-ware solutions used for measu-

The Acoustics Center - whereArtemiS, SQlab and ArtificialHead are used

rements at Volkswagen AG alsoapplies to the facilities of the Vehi-cle Acoustics Department: Thenewly established Acoustics Cen-ter is equipped with several testbenches and dynamometers aswell as a listening studio for theaurally-accurate playback andevaluation of artificial headrecordings made with the HMS IIIfrom HEAD acoustics. Since thesound and vibration characteris-tics, along with the visual design

Screenshot of the acoustics program for the remote control of ArtemiS

Golf A5 on a chassis dynamometer with an artificial head in the driver’s position

Page 7 May 2004

Did you know that ...

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text boxes containing user-defined information can becreated automatically in ArtemiSdiagrams?

with the keyboard shortcut[SHIFT]+[G] you can have thenumerical values of the cursorposition written directly into atext box at the correspondingposition in the diagram?

files from the ArtemiS SourcePool or from the WindowsExplorer can be dragged anddropped into the Mark Analyzerwith the mouse?

a new Download Area hasbeen established on our web sitein the “Support” section? Thereyou will find all currently avail-able documents from HEADacoustics, e.g. datasheets,application notes, brochuresetc. You will find the DownloadArea under: http://www.head-acoustics.de/Download_Area_e/Download_section/Down_over_e.htm .

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the new ArtemiS Recordercan be operated entirely via thekeyboard?

Tradeshows & Conferences

We are looking forward to your visit.

May 25-27 Testing Expo 2004 in Stuttgart/GermanyCome and see us in our booth 1110 in hall 11.Among many other product news we will bepresenting the SoundSeat from HEAD acoustics.See for more informationabout this tradeshow.

May 24-28 ASA Meet ing, New York , NY, USAHEAD acoustics GmbH and HEAD acoustics Inc.will be taking part in the conference with severalinteresting lectures, e.g “Transfer of knowledgefrom sound quality measurement to noise impactevaluation” or “Relationships of level, loudnessand time structure in pipe organ registration anddesign”. See http://asa.aip.org to find outmore about the conference.

Aug 22-25 InterNoise 2004, Prague, Czech RepublicHEAD acoustics will be present with a booth anda speech by Dr. Klaus Genuit. Visit the website

for more information.

www.testing-expo.com

www.internoices2004.cz

Events in the next quarter of 2004

May 2004 Page 8

Ebertstraße 30aD-52134 HerzogenrathTel: +49 (0) 2407 -577-0Fax: +49 (0) 2407-577-99eMail: [email protected]: www.head-acoustics.de

Represented by