Meeting Topic: Automatic Microphone Mixing: How and Why?
Moderator Name: Jay Dill and Nate Sparks
Speaker Name: Michael Pettersen and Gino Sigismondi, Shure
Other business or activities at the meeting: General welcome, introduction to the section and section’s website/social media, and information on joining the AES for non-members.
Meeting Location: Online (YouTube stream with Q&A)
Summary:
Moderator’s Jay Dill and Nate Sparks joined Shure’s Michael Pettersen and Gino Sigismondi for the Central Indiana Section’s inaugural webcast to discuss the history and current state of automatic microphone mixing. The presentation began with an in-depth overview of the history of automatic mixing dating back to the original concept brought forward by famed theatre sound designer Dan Dugan. Dugan’s initial concept allowed a theatre mixer to offload the task of muting and unmuting (or fader riding) multiple microphones as actors delivered lines and entered or left stage. This functionality helps optimize gain before feedback, prevented comb filtering, and reduced buildup of background noise and reverberation.
Shure entered the automixing market in the early 1970s with the Voicegate, a speech-centric gating system. By the mid-70s, advancements allowed for variable threshold operation, as well as implementing gain sharing, a system which maintains a sum total gain for all open channels as channels are added or subtracted, thereby creating a more stable system. Further advances heralded a dual-element microphone with a secondary, rear-facing capsule providing a differential to ensure only on-axis input signals triggered unmuting, and system linking to allow for more channels.
The next wave of development included adaptation to ambient noise and the ability to work with non-proprietary microphones. This system grew into the famed FP-410, which included MaxBus, a system to ensure that the loudest receiver capturing a single source would remain open, a system to ensure that the last microphone used would remain open, and the implementation of “off-attenuation”, which used approximately 15 dB of gain reduction rather than full muting of sources. These technologies have rolled into the systems we know as IntelliMix.
As the world of audio migrated way from analog processing, IntelliMix went digital. While the aims of automixing remain the same, the processing tasks of signal detection, channel priority, gain-sharing, etc. have been merged into DSP-based systems in both hardware and software. Current automixing offerings retain this functionality, but also allow for configuration of all aspects of the system via a browser-based GUI. Traditional functionality can also be coupled with additional audio enhancement processing and digital I/O for maximum flexibility.
The presentation was facilitated by Force Technology Solutions’ live streaming studio, allowing broadcast-style graphics and switching, off-site production, and remote presentation from across the Midwest. The lecture can be can be viewed on the Central Indiana Section’s YouTube channel or directly at https://youtu.be/diWqymbEuhw.
Written By: Brett Leonard
Indiana Section - Audio Engineering Society 