Relevance and treatment of the low frequency domain for noise control and acoustic comfort in rooms

This paper questions traditional acoustic treatments which, actually, have little impact on the room acoustics at low frequencies. This is a problem as poor speech intelligibility and the annoyance feeling often are caused by the high background noise at low frequency, but it is not yet recognized widely. It is amplified that today the acoustics of such rooms can be corrected by using Compound Panel Absorber (CPA) and Broadband Compact Absorber (BCA) treatments. The CPA is a low frequency absorber covering 50 to 500 Hz and the BCA is a broadband absorber which provides constant absorption over the entire frequency range of interest in room acoustics. The two absorbers are of thin structure and at a good cost. Examples of successful applications of these slabs in representative enclosures for various communicative uses are presented in this paper.