Proceedings of 20 th International Congress on Acoustics, ICA 2010 23-27 August 2010, Sydney, Australia ICA 2010 1 Control of sound insulation in glass facades at Oslo’s Opera House Sigmund Olafsen, Per Kåre Limmesand Brekke & Strand akustikk as, Oslo, Norway PACS: 43.28 Hr, 43.55 Rg ABSTRACT Oslo’s opera house, new in 2008, has several large glass areas in the facades. The site is located in an area with heavy traffic. At the design stage, it had to be taken into consideration that the opera house might have to be useable with traffic noise at a level of LAeq = 70 dB outside through a period of many years. The façade to the east has large glass areas for several rehearsal halls. Sound insula- tion against traffic noise into these halls is critical for the success of the opera project and had to be tested. Three of these halls are on level 4 with no access to the outside of the building. The field testing of the actual sound insulation in the finished building presented severe practical challenges. It was not practically possible to measure outdoor and indoor levels simultaneously. Thus great care had to be taken to insure that the sound field was as similar as possible during outdoor and indoor measurements. Two sets of amplifier and loudspeaker were needed to achieve a sufficiently diffuse and repeatable sound field on the outside of these facades. The paper will deal mainly with a description of the practical arrangement of and the results from the measurement. Other aspects of sound insulation in facades have been treated in earlier papers which will be referred to. INTRODUCTION There are three rehearsal halls on the east façade of Oslo’s new opera house. All these halls have an external wall with a glass-onlyfacade. The outside of these glass walls are ex- posed to steady traffic noise of around 70 dB daytime LAeq. Strict requirements had been given for the sound insulation of these facades and the indoor levels. The final requirements were as given in the table below. Table 1. Sound insulation and sound level requirements Room LAeq in room Rw+Ctr Rehearsal hall A 20 dB 43 dB Rehearsal hall B 20 dB 33 dB Rehearsal hall 4 30 dB 33 dB Source: Note 68 on sound insulation requirements for facades, last revised januray 5th, 2005 [1] MEASUREMENT METHOD Situation The east wall of the opera has no external access. This means that the microphone must be mounted either up from the ground or down from the roof of the building. It would not have been practical at the time the measurements were made to use a lift to make the measurements from the ground up. The measurements thus had to be made lowering the micro- phone from the roof. Figure 1, Rehearsal halls B and 4