Acoustical reconstructions of three university halls in Zagreb

摘要

Three different halls at the Zagreb University were acoustically reconstructed with appropriate materials to reach sound quality standards. In an old fashion amphitheatre hall of the Medicine faculty it was necessary to lower reverberation time, diminish flatter-echo and generally improve two-way speech intelligibility between lecturer and audience. In the half-oval Lecturers club hall on the Faculty of EE and Computing it was necessary to add sound absorption and to remove flatter-echo, but at the same time to give the hall liveness necessary for musical performances. The Multimedia hall of the Faculty of Teacher Education should first of all enable movie projections with surround sound reproduction, small acoustical group performances, but also standard university lectures. Acoustical reconstruction had to be realized within short University budget, with ready available materials, aesthetically convincing and within short time without much disturbing of the education process. After reconstructions, halls had to preserve same form and dimensions. The verification of acoustical improvement was asked, thus measurements of acoustical properties were performed before and after reconstruction. The impulse response was targeted as the most important parameter. The paper presents a comparison of simulated reverberation times and measured results after acoustical reconstruction. Results have shown various possibilities and the quality of some standard materials, as well as the verification of measured acoustical absorption coefficients.