Dept. of Appl. Acoust., Chalmers Univ. of Technol., S-412 96 Goteborg, Sweden
For a long time European building codes have included requirements on sound insulation between dwellings as well as noise levels from indoor and outdoor sources. Minimum requirements on sound insulation in finished buildings are based on the ISO documents 140 and 717. Typical minimum requirements lie in the range R[inf w][sup '](greater than or equal to)52-55 dB and L[inf nw][sup '](less than or equal to)53-58 dB. Today's trend is to extend the frequency range down to 50 Hz and to sharpen the minimum requirements somewhat, which creates some problems. In response to increasing demands from consumers, different classification systems for the sound insulation have been developed. The highest class demands insulation values up to 10 dB better than the legal requirements. A-weighted levels from building installations may not exceed 30--35 dB. To limit low-frequency ventilation noise C-weighted levels are specified in addition to A-weighted levels. Traffic noise levels are based on L[inf eq] as a L[inf dn] or as separate values for day and night. Typical demand is L[inf Aeq]<55 dB outdoors and 30 dB indoors. In existing situations, these levels are often exceeded. Effort is now being spent in the European community to deal with this problem.