Service 3: Back-end Signal Processing Functions
PRIR/BRIR files held in a members depository can be enhanced using a number of proprietary signal processing functions. This suite of functions will be expanded over time to include other options such as room equalisation.
1. Personalisation of a BRIR
A BRIR of a high fidelity sound room can be personalised using information from a member’s PRIR. The algorithm comprises a three step process and has the capability to dramatically improve the localisation of the loudspeakers and suppress unnatural room colouration. It does not alter the nature of the room acoustics nor the reverberation. While personalising a BRIR is unlikely to ever sound superior to a PRIR made by the member in the same room, the improvement can be very useful where this is not an option and will often result in a better sounding room than a PRIR made in a regular room. As a result, this option should give members access to a much wider selection of decent sounding files.
The process does require that the member have a PRIR that contains loudspeakers whose positions are similar to those in the BRIR. The enhancement process does not make use of the reverberation portion of the PRIR so the acoustics of the room used to make them are irrelevant. Neither does the enhancement process make use of the lower frequencies of the PRIR and so the loudspeakers used to make the PRIR measurement need not be full range. Indeed, PRIR measurements, for the purpose of enhancing a high quality BRIR, can easily be made at home using only a single tweeter connected to the mono speaker output (A16) and using the ONE measurement with the new head tracking pilot guidance system to establish the appropriate head-to-tweeter orientations. While tedious, measuring a PRIR file for personalising BRIRs would theoretically only need to be made once, provided a good range of different tweeter-to-head positions were included during such a measurement.
We are currently putting together a low cost measurement kit that would include the tweeter driver and adjustable stand as an accessory to the A16 for this purpose. More details will be released in due course.
2. Mimicking a BRIR
Any PRIR a member holds in their account can be modified to sound like any BRIR in their account. Essentially the time and frequency characteristics of the PRIR measurements are altered to match that of the selected BRIR. For example, a user may have a good sounding home theatre, but they prefer the excellent low frequency damping of a certain studio listening room. The process would mimic this reverberation characteristic.
3. Reverberation Modification
Any PRIR or BRIR a member holds in their account can be processed to alter the time-frequency characteristics of the room reverberation to their liking. This is a bit like a graphic equalizer except you are controlling reverberation decay time in frequency bands rather than amplitude. This process can change a PRIR of a not very good room into a PRIR with a very acceptable room, in an instant.