Efterklangstid i mindre lyssningsrum : Beräkning och mätning utav efterklangstid samt stående vågor

Sammanfattning

This project deals with calculations and measurements of reverberation time inside a small listening room. The purpose is to gain knowledge of the acoustics in a furnished home. Also, how music productions made within are affected by the room’s acoustic conditions. Work began with calculations which were later compared with the measured results. The rooms theoretical acoustics were calculated with equations for reverberation time, standing waves and total absorption. Measurements of the room used balloon bursts as an impulse source. The bursts were recorded and then analysed. The calculated results differed from the measured results. The calculated results deal with an empty room were as the measured results deal with a furnished room. Calculations resulted in an estimated reverberation time of 2.8s when averaged over six octave bands. The main difference between the measured and calculated results is the absorption of the furniture in the room. The measured results show that the room has an even reverberation time of around 0.5s throughout all measured octave bands. Likewise, the room has an even frequency response except for a small increase at midfrequencies between 500Hz – 2 kHz. This increase affects most fundamental frequencies of instruments in a standard rock or pop band setup. Music productions are affected by standing waves which increases and cancels out certain frequencies. By applying the rooms measurements with Bolt’s region, which determines whether the room has an even distribution of low axial-mode frequencies. The room measurements fall just outside of the region; therefore, the room has an uneven distribution of low axial-mode frequencies.