During the previous ADCs significant focus was given to software used in music production. But what happens to our precious audio signal once it leaves the mixing console during a live performance? Is there any cool or interesting software used in live sound system applications, which neither the artist nor the audience may be aware of? I'm here to tell you that there is! There are complex and compelling software algorithms involved in the planning and design of live entertainment events. Even during live performances software and signal processing play a vital role in bringing the music to every seat in the audience, bringing a smile to every face.
Starting from the planning and simulation phase of a large sound system, I'll give you a glimpse of the software tools which are used to design some of the biggest concerts out there. Some of these tools facilitate performance prediction, alignment, rigging, and also help ensure safety concerns are met before a single loudspeaker is hung. Using sophisticated mathematical models and high-resolution dispersion data, the wavefront of each loudspeaker within a line array can be synthesized. Precise simulations of the level distribution can then be calculated and viewed in a three-dimensional representation of the venue, which can significantly reduce setup and tuning time in touring applications.
The choice of loudspeakers can make a dramatic difference in attaining the desired level distribution. Active and passive cardioid loudspeaker designs, combined with the correct signal processing, can provide excellent sound directivity. Analogous to their better-known microphone counterparts, cardioid loudspeakers exhibit high levels emitted to the front, and low levels to the rear. Directivity enables a sound system to project sound to where it is needed (the audience) while keeping it away from areas where it is not desired, resulting in better sound quality and intelligibility.
Going over to the setup of the sound system at the actual venue, I will show you some of the tools available for checking the integrity of amplifiers and loudspeakers. Focusing specifically on line arrays, I will reveal the inner workings of Acoustic Neighbor Detection, a patented algorithm which helps ensure that individual loudspeakers within a line array or a sub-woofer array are positioned in the right order. This helps to avoid cabling errors, which are unfortunately quite common during time-critical setup procedures.
Finally, in addition to the common EQ, compressor and limiter options found on most modern power amplifiers (outside the scope of this talk), there is a significant amount of signal processing which can take place during the most important time of all, i.e. the live performance. An interesting challenge is achieving a truly uniform frequency response over large audience areas, while also compensating for air absorption effects over long distances. One of the techniques involves the use of individual sets of FIR and IIR filters for every single loudspeaker within a line array, each of which thus requiring a dedicated amplifier channel. These filters shape the sound generated by the array to precisely match a user defined level distribution and obtain the desired frequency response, achieving true "democracy for listeners".
