Calculating traffic noise reduction at long distance using diffracting elements

A series of resonators alongside a road or railway can be used to diffract noise upwards to create a zone of noise reduction behind the elements. The company 4Silence developed the so-called Whisstone, a concrete block with 18 resonators of different depths designed to operate in a broad frequency range. Several measurements at short distance,...

Reduction of uncertainties for a model based measurement system for impulsive sound events

The use of combining sound measurements and sound propagation modelling is increasing. In this paper the acoustic situation on and around a shooting range is considered. A monitoring system that automatically detects and localizes impulsive sound events is presented. The locations of these events are obtained by combining detections from...

Long-term monitoring of time-varying sound propagation from a large industrial area

A long-term monitoring project, with 12 months of continuous operation time, is described where the sound sources within a large industrial area as well as the sound levels in the nearby residential area are measured. The sources in the industrial area may give rise to complaints from the neighboring residential areas, at several kilometers...

Active control of a lumped acoustic source driven by various actuators

This paper studies a lumped model of an acoustic source with a relatively small thickness and high bending stiffness. Voice coil and piezoelectric actuators are used to drive moving components of the acoustic source. Feedback and feedforward damping control techniques are used to actively obtain a smooth frequency response, especially at low...

Traffic noise and vehicle movement at a controlled intersection

Traffic noise at an intersection controlled by traffic lights shows noise level variations due to the alternating green and red lights for the different trafficstreams. Noise peaks caused by automobiles pulling up or passing by at highspeed may be quite annoying for people living near the intersection. Detailedprediction of the variations is...

Local impact assessment of urban traffic noise

Assessment of reflectivity of noise barriers in the far field – QUIESST method compared to traditional approach

The sound reflectivity of noise barriers elements is one of the major acoustic product characteristics. Traditionally this property was tested in reverberation rooms according to EN 1793-1 and the results were used to predict the effect of sound reflections in the far field. As in many cases these results cannot be used directly to assess the...

Tracking and convergence of multi-channel Kalman filters for active noise control

The feed-forward broadband active noise control problem can be formulated as a state estimation problem to achieve a faster rate of convergence than the filtered reference least mean squares algorithm and possibly also a better tracking performance. A multiple input/multiple output Kalman algorithm is used to perform this state estimation. To...

New EU and UN/ECE Vehicle noise emission limits and associated measurement methods

In 2013 or early 2014 the European Union will decide upon a new “Regulation on the sound level of motor vehicles”. It will specify a new type approval test method for noise emission and will give revised limit values for the permissible noise emission per vehicle (sub- category. The new regulation may be seen as a final stage of a long series of...

Automatic classification of urban traffic noise onboard an acoustic monitoring system

Recent developments in acoustic monitoring systems make it possible to measure complex noise situations, like urban traffic noise, continuously. Monitoring provides more insight in the noise situation, from which more specific and (cost) effective measures can be taken. Monitoring also allows direct evaluation of the effect of mitigation, or to...

Flat sources for active acoustic shielding based on distributed control of a vibrating plate coupled with a thin cavity

Air cavities between plates are often used to improve noise insulation by passive means, especially at high frequencies. Such configurations may suffer from resonances, such as due to the mass-air-mass resonance. Lightweight structures, which tend to be undamped, may suffer from structural resonances as well. Active methods have been suggested...

Directional sound sources using real-time beamforming control

Quiet vehicles may be noticed relatively late and therefore constitute a potential risk for vulnerable road users such as pedestrians and bicyclists. The ideal acoustic warning signal generator notifies vulnerable road users while minimizing noise pollution. Several sensor systems exist which are able to reveal the position of the vulnerable...