Sound attenuation in long enclosures.

An intensive review indicates that among the existing formulae on the sound attenuation in long enclosures, only the geometrical reflection model seems relatively practical. Computations with this model show the following for rectangular long enclosures: with a larger cross-sectional size the relative attenuation from a given section is less but the absolute attenuation with reference to the source power is greater; the efficiency of absorbers is higher when there is less absorption; and obtain a higher attenuation, the absorbers should be evenly arranged in a section.

Thermal and acoustical performance of "buffer rooms".

The term "buffer room" refers in this context to spaces built between thermally, visually, and acoustically "controlled" indoor rooms and the "no controllable" outdoor environment. Examples of buffer rooms are sunrooms, atria, (enclosed) staircases, and air locks. In a long-term research effort carried out in Austria, buffer rooms were studied with regard to their hygrothermal and acoustical performance within a human-ecological framework.

Acoustics Part 2.

            

Acoustics Part 1

    

IEA Annex 27: Evaluation and demonstration of domestic ventilation systems. Assessments on noise.

The acceptance and appreciation of ventilation systems is mainly determined by the perceived indoor air quality, thermal comfort and noise. Noise in relation to ventilation systems can be divided into three categories: outdoor noise (entering the dwelling through ventilation openings, cracks, mechanical supply and exhaust openings etc.); noise generated by components of the ventilation system; the impact of ventilation systems on sound reduction of partitions (between dwellings, rooms etc.). Depending on the type of ventilation system, one or more of these aspects are of concern.

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