Applied Acoustics at TNO

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1 Applied Acoustics at TNO Environmental noise sources and propagation Management and control of noise and vibration remains a key issue for health, safety and well-being of society as a whole. Noise exposure and annoyance have to be kept within limits both in the environment, at the workplace, on the move and in the home. With increasing numbers of sound sources around us, the technology and solutions to better design and control them are essential. Acoustical techniques are also used for diagnostic purposes and detection. In the field of acoustics TNO offers expertise and innovative solutions covering environmental noise, occupational noise, product quality, detection and diagnostics technology. TNO can develop intregral solutions by taking the whole chain from source to receiver into account, in a multidisciplinary approach.

2 TNO has been active in acoustics for several decades, providing R&D and consultancy services for industry and the public sector on noise control at the source, in the propagation path and on exposure and perception at the receiver. Capabilities include model development (numerical and theoretical), experimental testing and monitoring, system and software development, product innovation and impact and policy studies. Through involvement in European research, standardisation work and links with universities and partners, a broad range of expertise and solutions is available. requirements. The TRIAS model for road/tyre noise has been developed enabling prediction of noise emission of different tyre designs. In the scope of the Qcity project a decision support system is being developed that allows the assessment of action plans as required for the European Environmental Noise Directive. TNO has also played a role in the Dutch PIEK programme on the assessment and reduction of goods delivery noise. Vehicle noise monitoring on a motorway Environmental noise assessment, modelling and control Environmental noise is a key expertise at TNO, including noise at the source, propagation and perception, for road, railway, aviation, shipping, industrial and military noise. TNO is closely involved in the development of the Dutch statutory calculation schemes and new European prediction models such as Harmonoise/IMAGINE. Prediction models for both noise and air quality are combined in URBIS and the interactive 3D planning tool Urban Strategy. Modelbased monitoring tools are available for the assessment of noisesensitive locations such as motorways in cities, junctions, railway yards and airports. Advanced propagation models developed at TNO such as PE, which also can be coupled to meteorological models, are used to predict sound propagation over large distances. These models allow modelling of geometrically complex situations including street canyons, propagation over built-up areas and over water and undulating landscapes. Detailed studies have been performed on noise barrier design and on meteorological effects such as reswing (affecting transmission over barriers). Calculation of noise transmission on a road noise barrier T-top Railway noise Railway noise expertise at TNO includes modelling and measurement of rolling noise of vehicle/track systems including steel bridges, curve squeal, traction, braking and aerodynamic noise and other sources. Prototypes of low noise track and bridges have been developed, now put into practice. TNO has developed several measurement procedures for noise emission at railway yards and for type testing. A special test rig for research on curve squeal has been built. The TNO Pass-by Analysis (PBA) software allows measurement of vehicle and track characteristics including combined roughness and track decay rates from a single train pass-by. Both trackside and on-board monitoring measurements are performed, either for type testing or analysis purposes. Noise map of Rotterdam in Urban Strategy Road traffic and vehicle noise Road traffic is a major noise source. Using model-based monitoring techniques and noise mapping, TNO can evaluate vehicle noise emissions on motorways and in urban areas. This provides insight into current trends and vehicle and infrastructural noise control measures such as traffic management, barrier design and vehicle Noise testing on a freight train with low noise brakes Curve squeal test rig

3 Aircraft noise Noise around airports is an ongoing issue with continuing growth in air traffic. TNO has performed source strength measurements at airports and proposed new solutions such as novel architecture and ground profiling along runways to reduce aircraft ground noise. Active noise control solutions are under development for reducing noise received in dwellings. Model-based monitoring around airports has been developed to allow prediction of the dynamic noise map of individual aircraft depending on the type, the position, power settings, angle of ascent and weather conditions. Netherlands Navy Frigate Underwater technology research at TNO, both theoretical and experimental, covers underwater observation systems, underwater environment and underwater threats. Core competences are: design, construction and testing of passive and/or active sonar systems for application in anti-submarine warfare, mine counter measures and torpedo defense; supplying of innovative underwater technology systems; consultancy partner of the Royal Netherlands Navy in their role as smart specifier, purchaser and user of underwater technology. Industrial noise Source modelling of aircraft and predicted impact Assessment and control of industrial noise at TNO includes site noise mapping, source location, troubleshooting, investigation and configuration of noise control measures. This is done for example for harbour facilities, process industry, manufacturing plants, logistics facilities and others. Abatement measures include operational control, layout, component selection, acoustic devices such as silencers, enclosures, vibration isolation, damping and absorption. A special example is a study in the Rotterdam harbour area where the sound propagation is studied over land-water crossings to receivers in a town several kilometers away. Measurement of aircraft ground noise Ship acoustics, underwater acoustics and sonar For five decades TNO has provided R&D and consultancy services to navies and commercial shipbuilding industries. A wide range of analytical, experimental and computational knowledge and tools are available, and solutions include both passive and innovative active technologies to isolate noise sources. Due to the high demands on the underwater acoustic signature of naval ships, the low noise philosophy is present early in the design stage, as well as the search for cost-effective solutions. The knowledge obtained in this field is also applied to control the impact of man-made underwater noise on the environment. Dry bulk terminal at Rotterdam

4 Impulsive and military noise Impulsive noise such as firearms and explosives is a particularly critical source, as it causes stronger reactions and is perceived differently from continuous sources such as traffic noise. To enable the prevention or reduction of unwanted effects of these sounds, TNO has designed many field and laboratory studies on audibility, loudness, annoyance, startle and sleep disturbance. The experimental results have led to an efficient general method for rating. Control measures for impulsive sources have been developed. Source and propagation models developed at TNO have resulted in a decision support tool that allows scheduling of military exercises, depending on the noise propagation over large distances affected by weather conditions. Product improvement and noise control at source Noise emission of machinery, appliances and vehicles often needs to be limited due to environmental, occupational, detectibility, product quality or comfort requirements. TNO has the tools and expertise to diagnose and analyse the noise sources and transmission paths, and the knowledge of noise control solutions suitable for practical application. For the development of quieter products, measurement diagnostics are applied besides calculation tools including FEM, BEM, SEA, CAA, CFD and some developed in house such as EQUIP+, CABIN and Exhaust. Application examples are construction and materials handling machinery, medical equipment, vehicle interior noise, office and household applicances, plant equipment and production machines. Standard testing can be performed in both laboratory and field conditions. Flow acoustics facilities and models are available. Firearms noise emission measurement Ground-borne vibration Ground-borne vibration from roads, railways and construction work are a source of structural damage, vibration annoyance and vibration induced low frequency noise in buildings. TNO performs measurements and calculations to assess and predict the effects of vibration and designs innovative mitigation measures at the source, in the ground and in buildings. From global assessments to detailed modelling, much attention is paid to uncertainty and reliability. Diagnostic noise measurements on the hydraulic unit of a firefighting vehicle EQUIP+ Noise path model of a compressor Vibration measurements in a new railway tunnel

5 Active noise and vibration control After many years of research, active noise and vibration control is finding more practical applications due to faster algorithms, less expensive, lighter and more powerful hardware. TNO develops ANVC systems for specific applications including passenger compartments, enclosures, panels, isolators and machinery components. Several patents have been granted and modular control software and hardware are available. components and joints (UMASIS). This is used to prototype measurement systems and diagnose measurement results. Simulation of ultrasonic testing of piping joints (UMASIS software) Architectural acoustics Reduction of sound transmission using piezo panels To improve the acoustic climate in buildings TNO has well established models for sound transmission in buildings for airborne sources such as service equipment and for impact sources such as footstep noise. For the proper modelling of existing buildings and new designs, focus is on measurement and calculation of the acoustic properties of building elements and systems, helping industry to innovate. Noise and vibration monitoring Besides environmental noise monitoring, asset and machinery condition monitoring systems can be designed and tested either as permanent or temporary remote installations. The Andante system developed for monitoring environmental noise at railway yards, can locate and characterise the noise source and register it on video. Monitoring of noise using microphone arrays is used to detect and locate incidents in public spaces. Sound insulation measurements on a window in an insulation chamber Perception and dose-effect relationships Andante monitoring system for noise events at railway yards Ultrasonic measurement technology TNO is specialised in ultrasonic inspection techniques for fluids, materials and structures. Applications include flow rate measurement, particle detection, corrosion monitoring of piping and inspection of welding joints. A software tool has been developed which allows the prediction of wave propagation in structural Perception of different types of noise source and subsequent annoyance can differ per source type and are often related to psychological factors. For example shooting noise, high speed trains and road traffic may be perceived quite differently depending on the association made by the observer, but also on the context, situation and combination with other sources and non-acoustical factors (light, odour, vibration). TNO performs both field surveys and laboratory studies to investigate sound perception, taking into account psychological, subjective and sound quality aspects. Community surveys have been used to derive dose-effect relationships for

6 the effect of transportation on self-reported annoyance and sleep disturbance. The percentage of (highly) annoyed or sleep-disturbed people can be predicted for a given exposure level and source. Also physiological parameters indicating sleep disturbance have been investigated, such as movements and autonomic nervous system activity during sleep, as well as effects on health parameters such as hypertension and cardiovascular disease. TNO s clients include: National, municipal and European authorities Ministry of Defence and defense organisations Infrastucture design and management organisations Railway companies and industry Navies and commercial shipbuilding industries Automotive industry and associations Aircraft industry and airports Process industries and suppliers Manufacturers of machinery, equipment and appliances Supply industries for building and construction Engineering companies Measurements in a room with variable acoustics Speech and hearing TNO applies scientific knowledge about human auditory and speech production systems to enhance human performance in a technical environment. The main research topics are Hearing (including binaural/spatial hearing, 3D audio, hearing protection, noise annoyance, design and evaluation of warning signals), Speech Communication (including intelligibility, quality, speaker recognizability, certification of public address systems, overall assessment in real-time scenarios) and Speech Technology (speaker identification and verification, keyword spotting, evaluation of speech-to-speech translation and text-to-speech systems). Facilities Anechoic chambers Reverberation and transmission chambers Numerical tools for vibro-acoustic analysis Multichannel measurement equipment Monitoring systems Wind tunnel Scale model TNO software packages Acoustics TNO Science and Industry Michael Dittrich, Frank van den Berg Acoustics Department Stieltjesweg 1, 2628 CK Delft, The Netherlands T / F michael.dittrich@tno.nl frank.vandenberg@tno.nl TNO Built Environment and Geosciences Jeroen Borst Van Mourik Broekmanweg 6, P.O. Box 49, 2600 AA Delft, The Netherlands T F jeroen.borst@tno.nl TNO Defence, Security and Safety Ton van Koersel Oude Waalsdorperweg 63, P.O Box JG The Hague, The Netherlands T F ton.vankoersel@tno.nl Research on spatial perception of sound Joos Vos Business Unit Human Factors Kampweg 5, 3769 DE Soesterberg, The Netherlands T F joos.vos@tno.nl info@tno.nl Q062008/250