Measurement of the Low-Frequency Sound Insulation of Building Components
Abstract:Attention on sound insulation at very low frequencies is increasing. However, in typical European transmission rooms with a volume of 50–70m3 the reproducibility of sound insulation measurements is not satisfactory at frequencies below 100 Hz. The objective of the work described in this paper was to develop a new method of measurement in existing transmission rooms with the best possible accuracy at low frequencies (below 400 Hz). It was aimed to achieve a reproducibility in the frequency range 50–80 Hz not exceeding the reproducibility for the existing ISO 140 method at 100 Hz. This was obtained with a new method of measurement using new principles such as a corner source or moving loudspeaker, microphone positions in the source room close to the test object, an absorbing back-wall in the receiving room, and intensity measurements in the receiving room. The accuracy was estimated from theoretical investigations and measurements on four test objects at four laboratories. With the new method the standard deviation associated with the reproducibility was typically 2–3 dB at 50–80 Hz and around 2 dB at 100–125 Hz. For the existing ISO 140 method the standard deviation is approximately 4–6 dB at 50–80 Hz and around 3 dB at 100–125 Hz. For both methods the standard deviation associated with the reproducibility was in average 1.5–2 dB at 160–400 Hz. The measured sound insulation at very low frequencies was in average lower with the new method than with ISO 140. At 125–160 Hz there was no systematic difference between the two methods. A qualification procedure is proposed for checking each test facility, including the type and position of the sound source, and the efficiency of the applied absorbing material for the back-wall of the receiving room.
Document Type: Research Article
Publication date: 2000-05-01
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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