Room in room acoustics : using convolutions to find the impact of a listening room on recording acoustics

From experience and earlier investigations it is clear that room acoustical details in recorded music or speech can only be heard in a room having a reverberation time shorter than the one in the room in which the recording was made. The acoustical properties of listening rooms influence the perceived acoustics of the recording. In earlier investigations, the practical impact of listening room impulse responses on recording room impulse responses was shown by convolving many random combinations of measured room impulse responses. For more insight in the impact of listening room acoustics on rendered acoustics, in this new research, convolutions of synthetic impulse responses have also been used. Both the effect of the decay rate and the amount of direct sound were taken into account, where the resulting change in an acoustical property is assumed to be negligible if it does not exceed the JND (Just Noticeable Difference). Both theoretical and practical cases show that during playback, the decay curve derived from the recorded impulse response turns into a curve with a slow attack and a concave level decay line. The more both impulse responses (recording and playback room) are diffuse and equal in decay rate, the higher the impact. Even when using nearfield playback, it is very difficult to reduce the negative impact of a listening room on acoustical details in a recording.