Parlé Voice Lift: Frequently Asked Questions (FAQ)

General Concepts / Is PVL Right for My Project?

Q: What is the fundamental difference between Parlé Voice Lift and a traditional PA or Speech Reinforcement system?
A: PVL is designed for subtle, transparent reinforcement. The goal is to lift a presenter's voice just enough to maintain intelligibility for the furthest listeners, aiming for a Signal-to-Noise Ratio (SNR) of 10 dB above the room's noise floor. It should feel natural, as if the presenter's voice is simply carrying further. 

The industry generally defines system gain as follows:

• Voice Lift: 6 to 12 dB of system gain. The goal is transparency; it should feel as if the presenter's unamplified voice is simply carrying further.
• Speech Reinforcement / PA: More than 12 dB of system gain. At this level, the amplification is no longer transparent and is clearly a public address system.

Q: What is required of the presenter/participant in a PVL system?
A: The presenter or participant needs to talk clearly and at a reasonable volume. The system is designed to lift a normal speaking voice, not amplify a whisper. The target speaking level for a presenter should be approximately 60 dBA slow at 1 meter. If the presenter speaks too quietly, the system will have insufficient signal to lift effectively above the room's noise floor.

• This returns us to the Signal-to-Noise Ratio point from above, the PVL presenter needs to be 15-20 dB above the noise floor at the presentation stage area.
• If the noise floor is 40 dBA slow at the stage area and the presenter presents at 60+ dBA slow, there should be ample SNR for the PVL microphone(s).

Q: What is the difference between Presenter Lift and Participant Lift?
A: Presenter and Participant are considered subcategories of PVL:

• Presenter lift is a stage-to-audience (one-to-many) scenario intended for lecture halls and training spaces.
• Participant lift is an audience-to-audience (any-to-any) full mix-minus system designed for collaboration spaces.
  • Because Participant Lift calculates routing for everyone, it requires significantly more DSP resources.
  • In most cases, projects will be a "hybrid" combining a presentation stage subset with the larger participant lift area

Q: In what scenarios should I NOT use PVL/PPL?
A: You should not specify a PVL/PPL system if the room fails to meet the "Pillars of Success":

1. Poor Acoustics: If the room's noise floor is above 43 dBA or the RT60 is over 500ms, the system will likely not have enough stability to provide meaningful lift.
2. Small Room: If the distance to the furthest listener is less than 35 feet (10.7m), PVL/PPL will likely not have enough stability to provide demonstrable lift.
3. Unzoned Speakers: If the loudspeaker system cannot be discretely zoned and controlled, you cannot implement the gain mapping required for stability.
4. Microphone Mounting Height: If the Parlé TCM-X Microphones are mounted higher than 10 ft. (3 meters) AFF, the SNR will likely be too low for any form of stable voice lift.

Q: Can I deploy Voice Lift in a smaller boardroom (e.g., a 24-foot table)?
A: It depends entirely on the room acoustics and noise floor as captured and explained in the PVL Survey article. This concept sits right on the edge of functionality and Biamp highly suggests engaging a Field Sales Engineer to help review the survey information and advise accordingly.

Q: How important is the commissioning process to a PVL system's success?
A: Assuming the design is sound, commissioning is absolutely critical. Approximately 80% of a PVL system's success is dependent on the skills of the team deploying and commissioning it. This is not a "plug-and-play" or "check-the-box" feature. Success requires careful execution across all project phases, from initial site survey and noise floor measurement to precise installation and detailed audio tuning. Effective communication between the survey, installation, and commissioning teams is essential.

Q: Can a PVL system be used for audience microphones to reinforce audience questions?
A: Yes, a properly designed and commissioned PVL system can support reinforcement of audience questions. This was previously not possible as the initial release (Nov. 2025) only supported Presenter Lift.

Design and Hardware

Q: Can I implement PPL on a TesiraSERVER-IO or a legacy rack mounted TesiraFORTÉ (non-X)?
A: No. The Frequency Shift Feedback Suppressor block is essential for system stability and is only available on the TesiraFORTÉ X and Tesira VOLTERA D/DM (in special cases) platforms or systems that include these.

Q: Should I use Volterra D or DM amplifiers for Voice Lift?
A: While Volterra D and DM amplifiers support the required Frequency Shift block, they offer much higher output wattage per channel than is typically needed for PVL designs. The AMP-450P/AMP-450BP and TCM-XA products are more appropriately matched for the typical PVL design and the fact that they are PoE+ is also an advantage. When in doubt, contact your local Field Sales Engineer.

Q: Can I integrate PPL into an existing Dante-based system (e.g., a TesiraFORTÉ DAN)?
A: No, Parlé microphones require a bidirectional AVB connection for both audio and control data, including the critical back-channel information that freezes beams during far-end speech. TesiraFORTÉ DAN is not capable of supporting this AVB bidirectional communication. The TesiraFORTÉ DAN and TesiraFORTÉ AVB products don't support the Frequency Shift block needed for PVL either. If Dante connectivity is a requirement for other parts of the system, a TesiraFORTÉ X can be used to handle all PVL and conferencing processing while also adding Dante network connectivity options.

Q: Can I use AI Noise Reduction in the PPL signal path?
A: No. The AI Noise Reduction algorithm introduces significant processing latency (approx. 53ms), which is typically too latent for local voice lift. AI Noise Reduction should only be used in the signal path going to the far-end (e.g., USB or VoIP outputs).

• The standard Noise Reduction included within the AEC block has minimal latency and is used in the PPL signal path.
  • AEC Noise Reduction will likely be set to Low or Medium to help remove steady-state room noises. Setting this to High may help with other transient noises.

Q: What is the typical DSP resource usage for a PVL system?
A: DSP usage is significant and must be planned for carefully. The extensive per-channel processing for zoned loudspeakers consumes signigicant core DSP resources. For example, a system with 12 individually processed loudspeaker zones can consume over 75% of a TesiraFORTÉ X 400. In many cases, a PPL system will require multiple TesiraFORTÉ X processors or a server-class device to accommodate both the PPL and any additional conferencing requirements. Tesira software is the best tool for validating equipment needs during the design phase of the project.

Q: What are the DSP hardware limits for Participant Voice Lift?
A: As a rule of thumb, once a design exceeds 7 microphones by 7 loudspeaker zones, you will need at least two DSPs. It is usually more cost-effective to use combinations like a TesiraFORTÉ X 400 and 800 to accommodate the design. Always use Tesira software to determine equipment needs.

Q: If my Voice Lift design is slightly over the DSP limit, how can I trim it?
A: PVL block files are already quite lean. If you must trim processing fat, the best place to do so is the per-microphone PEQ. You can reduce it from 16 filters down to 14 filters across all microphones, but you must remember to change your feedback suppressor band count to match so you can still copy and paste parameters. Please realize such a decision is a compromise as system performance may be better with all 16 filters for each microphone path. Designing with appropriate DSP available overhead is suggested.

Q: Can I use a Tesira Launch report to survey a room for PPL?
A: Yes, a Launch Advanced report card can be a useful tool for gathering baseline acoustic data like Noise Floor and RT60 during the survey phase. However, it is critical to understand that PPL and Launch are not connected features. There is no "launch button" for PPL. The Launch report can help determine if a room meets the acoustic prerequisites, but the PPL system itself requires manual commissioning and tuning.

Q: How do I calculate gain mapping/shading and AEC references for a Participant Lift system?
A: Because the current Presentation Space Designer only calculates for the stage area, you must manually merge coordinates using both the Classroom Designer (for audience mics) and Presentation Space Designer (for the stage) into the interactive Parlé Voice Lift Calculator Excel spreadsheet. This interactive spreadsheet calculates the matrix mapping and AEC cross-referencing needed for commissioning.

Q: When should I choose a TCM-X/TCM-XA versus a TTM-X for PPL?
A: The Parlé TCM-X (ceiling microphone) is the primary choice for most PPL applications, as it provides excellent coverage for a presenter who moves around a stage or presentation area. The Parlé TTM-X (tabletop microphone) should be considered a special-case solution, such as for a fixed lectern where it can provide superior performance compared to a standard gooseneck microphone. There are also cases where Parlé TTM-X may provide strategic coverage of instructional whiteboards. If a whiteboard camera is deployed, a TTM-X may be a good recommendation.

Q: Does the Presentation Space Designer automatically calculate speaker delay for time alignment?
A: No, it does not. The designer focuses on microphone placement, beam aiming, and gain mapping. While adding delay to align the reinforced signal with the presenter's acoustic arrival time can improve localization in very long rooms, it is an advanced, optional tuning step that must be calculated and implemented manually. Field testing has shown that user preference for delay varies; some find it enhances the experience, while others do not perceive a significant benefit. It is an adjustment that can be made based on the specific room and listener feedback.

Installation and Placement

Q: Why is placing the microphone at the "lip of the stage" so important?
A: This forward placement provides the best geometry for the microphone's beams to cover the entire presentation area, from the very front to the back. Crucially, it also helps to physically distance the microphone from the first row of loudspeakers, which are typically set to the lowest volume and pose the greatest initial feedback risk.

Q: I've installed the TCM-X, but the physical Biamp logo isn't facing the front wall. Do I need to re-install it?
A: Physical orientation is required for beam aiming and consistency. The standard practice is to orient the microphone so the red alignment LED points toward "room north" (the main presentation screen or stage).

1. In the Parlé Mic block's control dialog, enable Orient Mics mode.
2. The microphone will illuminate a red LED segment and a green LED segment.
3. Physically rotate the microphone canister in its ceiling housing until the red LED points directly at the presentation screen ("room north"). The green LED will then point to the back of the room ("room south").
4. This ensures that the physical microphone orientation matches the default orientation in the software and design tools, creating a consistent reference for all technicians involved. It's very helpful when all team members involved in the project use the same reference point.

Q: What are the best practices for labeling and routing during installation?
A: It is critical that routing is logical and linear. Give all expanders and amplifiers a human-readable hostname (like "Row 1, Loudspeakers 1-3") so the commissioning team can track cabling easily in the equipment table. Using the "Locate" function on the amps and TCM-XAs will play an audible message to ensure field wiring matches the design. The installed microphones and loudspeakers need to match the position and labeling in the design plan.

Q: Should loudspeakers very close to the PVL microphones be turned completely off?
A: Yes. In most cases, any loudspeaker within approximately 12-15 feet (3.5-4.5 meters) of the active PVL microphone should be turned off (or attenuated to -100dB) within the Gain Mapping Matrix Mixer. This is calculated by the Parlé Voice Lift Calculator. 

Tuning and Performance

Q: Must I lock the microphone beams for PPL? Can't I just let them track the talker?
A: Yes, PPL beams must be locked. When left in its default tracking state, a Parlé microphone behaves like a very smart omnidirectional microphone, which works against stability in a voice lift scenario. By locking the beams and aiming them specifically at the presentation area, you gain an immediate 1 to 3 dB of stability. Remember that beam locking and aiming can be recalled via presets in Tesira. This allows for different room usage and configuration modes.

Q: Is there a way to set "exclusion zones" so tracking beams ignore certain noise sources?
A: No, this feature does not currently exist. Beams are either fully locked or fully tracking. Also note that a beam is a cardioid pattern (roughly 60 degrees wide), not a tight spotlight.

Q: How long does it typically take to commission a Voice Lift system?
A: Proper tuning is time-consuming because each microphone beam must be "rung out" individually for optimal performance. A reliable formula is to add the number of microphones to the number of individually driven loudspeaker zones, then multiply by 1 to 2 hours, depending on the experience of the technician. As with all things, experience builds efficiency in the long term.

Q: How does the Frequency Shift block work?
A: The Frequency Shift block prevents a feedback loop from building into an audible ring. It takes the incoming audio signal and shifts its frequency down (or up) by the defined amount. If that signal loops back through the microphone, it is no longer at the same frequency as the original source, so it cannot sum and build into runaway feedback. It is important to note this is a frequency shifter, which moves the entire audio band by a fixed amount, not a pitch shifter, which adjusts maintaining harmonic relationships.

Q: Why do I need to "ring out the room" with the Frequency Shift block bypassed first?
A: The system won't "ring" with the Frequency Shifter engaged.  When the Frequency Shifter shifts the audio signal, it effectively moves any sinusoidal resonances in the system, thereby preventing a positive feedback loops or "ringing".

Q: Why do I need to "ring out the room" with notch filters if the Frequency Shift block prevents feedback?
A: The Frequency Shift block prevents feedback by shifting the frequency of the audio signal on each pass through the system, preventing a resonance from building at a single frequency. However, "ringing out the room" first provides two key benefits:

1. Additional Gain: Properly notching out the room's primary resonant frequencies with PEQ filters can add another 1 to 3 dB of gain before feedback.
2. Reduced Artifacts: An overdriven Frequency Shifter can produce audible artifacts which can be distracting to people in the room. By reducing the system's natural resonances, the system will be more stable and transparent to the audience and users.

Q: How do I "ring out the room"?
A: See the guidance in the PVL Commissioning article. 

Q: The default Shift Amount is 6Hz. Can I use a higher value?
A: Yes, but with a trade-off. Increasing the shift amount (e.g., to 8Hz or 12Hz) can provide more stability against feedback. However, higher values can become subtly perceptible to listeners, creating a "chorusing" effect or slight tonal change that may cause listener fatigue over time. The 6Hz setting is the recommended sweet spot and default.

Q: When pushing the system gain, I hear strange "ghost trails" or a dive-bombing sound instead of a constant ring. What is that?
A: That is the Frequency Shifter operating at the upper limit of stability. The "ghost trail" is the sound of an impulse looping through the system. Each time it loops, its frequency is shifted again by the defined amount (e.g., 6Hz), preventing it from building into runaway feedback. If you hear this, it is a clear indication that you are operating past the upper stable limit of the system. There are two things that can be considered to minimize this:

• Lowering the upper limit of the user facing PPL Master gain control.
• Adjusting the Frequency Shift block to use a more aggressive amount (e.g., 8Hz or 12Hz).
• Test each of these or a combination of them before finalizing your decision.

Q: Why is the Gating Automixer in Parlé Presenter mode recommended over a Gain Sharing Automixer?
A: A Gating Automixer provides superior rejection of unwanted noise. The cardioid pickup pattern of a Parlé microphone beam is rather wide at lower frequencies and can capture noise from the audience. A Gain Sharing mixer would keep the microphone partially open, allowing this noise into the reinforcement system. The Gating Automixer in the new Presenter Mode mode offers several advantages:

• Higher Minimum Threshold: The threshold is raised from -30dB to approximately -12dB, preventing low-level noise from opening the gate.
• Steeper Advantage Gain: The Advantage Gain is set to 5dB, making it more difficult for a second microphone to open a gate when one is already active.
• Deeper Off Attenuation: This provides a significant benefit to system stability by minimizing the amplification of ambient room noise.
• More Gain Before Feedback: All of the above features mean that there are fewer mics feeding audio into the space. This makes it possible to achieve more gain before feedback and, therefore, more lift.

Q: What is the difference between "Gain Shading" and "Gain Mapping"?
A: The terms are often used interchangeably to describe the same technique. "Gain Shading" is a common industry term for progressively adjusting gain across multiple loudspeakers (like its use in line arrays). "Gain Mapping" can be thought of as the documented result of that process—a "map" of the specific gain values for each speaker zone in a particular room layout. 

Q: What is a recommended user control for a PVL system?
A: A commissioned PVL system typically has about 6 dB of usable range. We recommend providing the user with a simple control that defaults to a nominal "0" level, with the ability to adjust +3 dB (for a full room) and -3 dB (for a sparse room). A TEC-X 1000 wall panel is an ideal interface for this type of simple level control. If a 3rd party control system is available, TTP offers the same system control to the end user.

Advanced Topics / System Integration

Q: Can I retrofit PVL into an existing Tesira AVB system?
A: Yes, this is possible, but it requires careful survey and evaluation as if it were a new opportunity. A successful retrofit will likely require hardware additions and significant rewiring. The integrator must verify:

• Speaker Zoning: An existing single-zone 70V/100V speaker system must be rewired to support a multi-zone configuration, likely requiring the addition of amplifiers like the AMP-450P.
• DSP Resources: 
  • PPL processing requires the Frequency Shifter block (TesiraFORTÉ X).
  • PPL is DSP-intensive; the existing Tesira system may not have sufficient resources, often requiring the addition of one or more TesiraFORTÉ X processors.
• Microphone Placement: Existing Parlé microphones may need to be relocated to optimize their position relative to the stage and loudspeakers.

Q: When importing gain mapping from the Excel sheet, should I include the row and column headers?
A: Yes, it is highly recommended to check "Apply first row/column as label" during the import process. This ensures proper labelling within the DSP file aligning it with the planning documents.

Q: Can I use the PVL dynamic block generator for a mix-minus system using gooseneck microphones (e.g., a city council chamber)?
A: Yes, the generator can act as a time-saver by pre-constructing the mix-minus matrix for you. However, you must remember that the gain structures (such as the default 23 dB input gain) and specific DSP attributes are explicitly tuned for Parlé microphones and will need manual adjustment for standard goosenecks.

Q: Can the BMA 360 be used for Voice Lift instead of Parlé microphones?
A: This is not officially supported at this time. The feature is developed and tuned exclusively for "Parlé" Voice Lift Parlé mic arrays are designed to be distributed across a ceiling closer to talkers, providing better on-axis coverage as compared to larger array microphones such as the BMA 360.

Further reading:

• Parlé Voice Lift: Overview (Start Here)
• Parlé Voice Lift: Site Survey and Preliminary Design
• Parlé Voice Lift: Installation and Pre-Commissioning
• Parlé Voice Lift: System Commissioning