What acoustic parameters can be changed in INSPIRATA and why were they chosen?
All acoustic parameters that you can change in INSPIRATA start from the factual reality that is measured in the space and your changes are relative to that. We chose this method since not everyone is expected to be an acoustical consultant fully familiar with the practical aspects of, for example, C80 = -3 dB at 1000 Hz. But to increase or decrease the sound clarity compared to what it is now, is a lot more intuitive. Acoustic parameters can be categorized as temporal, energetic and spatial, although there are some other criteria like speech intelligibility, which are dependent on multiple factors. These acoustical parameters are objective criteria, or plainly put, numbers, that can be measured by acoustical consultants with appropriate equipment in real spaces, and they were found to correlate with certain aspects of our subjective impression of the acoustics of the hall. What else would an engineer want to adjust in a reverb other than those things that directly correlate with the subjective impression? Everyone knows the mother of all acoustic parameters, the reverberation time, but it is not really describing all aspects of the reverberation process or how that room will sound, it tells just its length. Probably you would not be able to holistically explain the quality of a musical piece by its duration, either. So we focused on more detailed parameters acoustical science has developed, like spatial and energetic ones. Among the spatial parameters, the most important ones we thought would work in an immersive context is the Apparent Source Width (ASW) and the Listener Envelopment (LEV). We implemented the change of these parameters without a specific target value, but as relative parameters, and right now, you can increase these compared to the initial state. To make the room sound narrow or monophonic, other methods are available (e.g., by setting the virtual microphones to be mono). For the energetic parameters, however, like the sound clarity (C50, C80, etc.), we developed a way in which you can both increase or decrease these values. Sound clarity is related to the ratio of early energy versus late energy of the reverberation process, and the sound becomes more clear when there is more energy in the early part. The interesting part here is that you can adjust the sound clarity without changing the reverberation time. In real halls, clarity and the reverberation time is correlated, and as you move closer to the sound you get a bit more clarity. In INSPIRATA, you can adjust clarity even without moving closer or further from the sound source, so you can essentially change the density of the early reflection pattern, in real time. Then there is reverberation time, of course, which you can adjust as a whole, as in a frequency-dependent way, or as ratios to add more warmth or brilliance to the hall. Just like how acoustical consultants design the real spaces.