Low and mid Frequency Design - Implementation of Room Acoustics in different Building Types and for different Kinds of Use

In offices and most other working environments a high speech privacy and a low noise level is desired to allow for concentrated work and calm work conditions. Hence a low Speech Transmission Index (STI) is required, as even irrelevant speech information at lower volumes can be extremly disturbing and performance reducing. At the same time working environments demand for other - often con-flicting - requirements such as transparency to ensure visual connections and daylight transmission, functional flexibility for diverse activities in the same space and for hygienic, environmental or secu-rity aspects. These requirements have to be balanced by a sensible and intelligent design and layout of absorbers and partition elements and partition. Three research projects investigated an optimised design of low and mid frequency absorbers for working environments to improve the acoustic and design quality of different products. Acoustically optimised indoor spaces may become more important in the future due to an increase of hearing im-pairments in the aging population as well as in the younger generations. This is seen not only as a technical but as a design challenge to balance optimised sound pressure levels, reverberation times and Speech Transmission Indices.