Aktive intensitätsbasierte Minimierung der Schalltransmission durch ein teilgeöffnetes Fenster

Abstract

Urbanization and the resulting problems are a major challenge for a large part of the inhabitants of cities and furthermore for the planet. The population of many cities around the world such as Beijing, China or Hamburg, Germany have been steadily increasing for several years. In addition to increasing CO2 emissions through rising numbers of private transport, the increase of sound pollution in urban areas contributes to environmental pollution. High noise levels have been shown to have a negative impact on health, especially cardiovascular diseases. As a conclusion, there are limit values to be observed in many countries in order to reduce noise, for example in the construction industry. In Hamburg there is a so-called Hafen-City-Clause, which ensures that a noise level of 30dB(A) is not exceeded at night when the windows in bedrooms are partially open. Standard windows often do not achieve a sufficient reduction in sound transmission to be able to comply with this limit value. The sound transmission can be minimized by the use of passive measures, but this is accompanied by a restriction of the ventilation through the partially open window. In order to enable unrestricted air circulation, active systems, so-called Active-NoiseControl (ANC) systems, can be used. These systems can be placed in the sound transmission path and reduce noise through destructive interference without restricting airflow of the window To design an effective active system it is necessary to examine the influence of sound transmission paths on transmitted noise. For further investigation of sound transmission, the complex geometry of a partially open window is simplified to a parameterizable two-dimensional gap. The transmission of noise is calculated analytically in a first step with a substitute model, from which requirements for an active system are drawn. In order to get a deeper understanding of the influence of a sound path on sound transmission, the influence of parameters of a small gap in relation to the wavelength and the influence of a control signal of an anti-noise source on sound transmission are investigated. As a result of the conducted analytical and numerical studies, an alternative approach of an algorithm for adaptive intensity-based noise reduction is introduced. In this approach, only sensors placed in the gap are used to reduce the transmission of sound. The presented approach is finally implemented in a rapid control prototyping system and the functionality is proven by an experiment.