Parlé Voice Lift: Overview
Parlé Voice Lift uses Biamp Parlé microphones to capture a talker’s voice and gently reinforce it through loudspeakers elsewhere in the room. By compensating for natural distance‑based attenuation, it delivers clear, natural‑sounding speech coverage without requiring handheld or wearable mics.
This approach is enabled by supporting Biamp features:
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Tesira Parlé Beams can be aimed and locked to a fixed position for precise coverage.
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These settings are preset assignable to accommodate room modes.
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Supported in TCM-X, TCM-XA, and TTM-X.
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Tesira Frequency Shift block minimizes acoustic feedback.
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Supported in TesiraFORTE X (and Voltera D and DM products in special cases).
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Design and commissioning tools/enablers
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Presentation Space Designer advises the design and commissioning of one-to-many concepts.
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Classroom Designer advises the design of many-to-many concepts.
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Parlé Voice Lift Calculator is an interactive tool that helps calculate the requisite gain shading for commissioning a project.
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The Pillars of a Successful PVL System
Before any technical configuration, it is critical to understand that Parlé Voice Lift is a complete system approach. Its success depends on proper room acoustics, system design, and meticulous commissioning. These are called the Pillars of successful deployment. Failure to meet these prerequisites will significantly compromise system performance.
The difference between a stable, effective system and one prone to feedback can be as little as 3dB of gain. This means attention to detail is critical in each pillar.
Room Acoustics
The acoustic environment is the most critical factor. Good speech communication depends heavily on room reverberation and background sound levels.
These values should be measured as part of the survey and design stages of a project. The following table provides guidance for assessing whether a room or acoustic environment is appropriate for voice lift.
- Noise Floor: The ambient noise level of the room (with HVAC running) should be at or below 43 dBA (NC-30).
- Reverberation Time: The room's reverberation time should be below 500 ms. Highly reverberant spaces cause speech to become unintelligible and significantly lower the intelligibility of the system.
The following table helps us see the correlation between Noise Floor and Reverb Time.
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Room Acoustics |
Noise Floor |
Reverb Time (RT60) |
Max. Mic-to-Talker Distance | |
| TCM-X | TTM-X | |||
| Good | 35-43 dBA | 400-500 ms | 3 meters (10 ft.) | 1.7 meters (5.6 ft.) |
| Great | 30-35 dBA | 300-400 ms | 3.8 meters (12.5 ft.) | 2.1 meters (6.9 ft.) |
| Perfect/Ideal | less than 30 dBA | less than 300 ms | 5 meters (16.3 ft.) | 2.5 meters (8.2 ft.) |
Room Acoustics of Good, Great, or Perfect are requisite for PPL.
Room Geometry
Parlé Voice Lift is most effective in spaces where natural voice attenuates over distance.
- Talker-to-Listener Distance: PVL provides the most benefit in spaces where the distance from the talker to the furthest listener is 35-40 ft (10.7-12.2m) or greater.
- Why it Matters: As defined by the inverse square law, a typical speaking voice will be 15-20 dB quieter at this distance. Parlé Voice Lift is designed to help overcome this loss at this distance. In smaller spaces, the provided lift may not be of noticeable benefit.
Loudspeaker System Design
The typical single-zone distributed loudspeaker system is insufficient for Parlé Voice Lift.
- Discrete Zoning: The system design must include discrete loudspeaker zones with independent amplification and DSP control. This is required to implement gain mapping, a technique where loudspeaker volumes are progressively increased for zones further from the talker, creating a more natural sound field and minimizing feedback.
Installation and Commissioning
The success of a PVL system hinges heavily on attention to detail through every phase—from initial surveys and room measurements, through design, to the precise orientation and positioning of microphones and loudspeakers during installation. Finally, commissioning and 'ringing out the room' must be executed with care. A single misstep can degrade system performance by 2 dB, whereas each well-planned and executed step can add 1 dB of stability and performance. With only about 6 dB separating failure from success, it's critical to allocate resources and plan each step with precision.
Process and guidance articles
Follow these articles in order to guide your project through each essential stage. For a successful outcome, use these in conjunction with the pillars of successful deployment described in the overview above.