Voice Lift in Large spaces using Ceiling Microphone

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Uninterrupted interaction between people makes any meeting successful. This interaction could be between two or more people in the same room, on the same floor sitting in their individuals rooms, between two organisations situated in two different cities, countries, between students and instructors and nowadays between school kids and Teachers

AV Conferencing Systems are being designed by the System Integrators and Consultants in such fashion where the participants can interact easily.

In some cases, conventional sound systems enable the audience to hear the presenter or instructor, but they don’t do anything to help the members of the audience  hear each other.

Whenever distance increases between a talker and a listener, speech level automatically drops. Sometimes it becomes difficult for the people sitting at one end to hear the voice of the instructor or participant at the other end.

In such scenarios, the necessity of a correct system arises and Voice Lift is the best suited option which works well in such scenarios. Voice Lift system amplifies the voices of people in one part of the room so that people in other parts of the room can hear them clearly. 

Voice Lift System is like a conventional sound reinforcement system that consists of microphones, digital signal processors, amplifiers, and loudspeakers. The only difference is that the room is divided into zones, and the microphones in one zone are reinforced with the loudspeakers in the farther zones. Voice Lift is often referred to as a ‘Mix-Minus’ system.

There’s no limit to the size of the room in which a Voice Lift system can be installed; ceiling height will have more of an effect than room size on the success of the system. In most cases the ceiling microphones are mounted between 8 feet and 12 feet above the floor; higher installations are possible but will depend on the room acoustics.

System Integrator & Consultants while selecting the Microphone for Voice Lift should consider that the microphones should have super cardioid or better narrow polar pattern in order to avoid pick up of unwanted sound & accurately pick up the talker. If the Polar patterns are wide or omni, chances of feedback increases and the whole system fails. The pickup area of each microphone should be aimed accurately so that it picks up the voice of the intended selection of the audience. 

A standard table microphone can be used with a Voice Lift system, but people like to install microphones which aren’t visible and don’t  obstruct the infrastructure.

Shure Microflex® Advance™ MXA910 ceiling array microphone is very useful in such scenarios. Because its directional pickup lobes are narrower than any shotgun microphone, the width and position of each lobe can be easily adjusted to precisely to match the selected coverage area. This feature allows the MXA910 to perform better than any other ceiling microphone solution in Voice Lift applications.  With consistent speech levels throughout the room and greater gain before feedback, the MXA910 can also deliver 9 dB more voice lift than conventional microphones in a typical application.

Unlike a microphone, a high quality speaker also plays a big role in the Voice Lift system as it delivers the output for which the whole system has been designed.

Meyer Sound MM4XP, a Miniature Self-Powered Loudspeaker is also a good tool. The directional polar pattern of the MM-4XP, especially at low frequencies, significantly reduces room excitation and increases intelligibility.  Participants sitting at the far end of the room can clearly hear the voice of the talker.  An active, single-driver directional technology minimizes energy consumption, weight, and cabinet volume. The optional U-bracket can mount the loudspeaker on walls and ceilings at adjustable angles.

There is another tool which also plays an important role in voice lift, the matrix mixer.

When the number of microphone channels increases, the amount of processing required increases. It’s recommended to consult an expert before choosing a DSP/Matrix mixer.

Allen & Heath’s AHM 64 Audio Matrix Processor supported by a comprehensive ecosystem of scalable I/O, control and Dante solutions does the Mix and minus of various inputs to various outputs at different level depending upon the design. 

AHM64 runs on latest FPGA technology. When compared with limited resources of a DSP, FPGA gives an enhanced processing power with very less latency of under than 1ms under maximum processing.

A perfect example of using Voice Lift application is IIM Kozhikode, where the Design Consultant and System Integrator decided to go with Voice Lift application using Shure MXA910 Ceiling Array Microphone.

To know more about Voice Lift application and Tools which can be used, please write a mail to [email protected]