Map the room before choosing a louder system
Walk the occupied area while the room is quiet and again while normal event activity is present. Mark hard parallel walls, glass, concrete, high ceilings, domes, stages, balcony faces, deep under-balcony areas, side alcoves, service bars, HVAC outlets, and open doors. Note where a talker’s unamplified voice changes from distinct to diffuse. A floor plan shows distance, but it cannot show every reflection, background-noise source, or acoustic shadow.
ISO 3382-2:2008, confirmed as current in 2022, specifies methods for measuring reverberation time in ordinary rooms, including apparatus, measurement positions, evaluation, and reporting. That multi-position principle matters for temporary events: one reading at front of house cannot represent a balcony, rear wall, side aisle, and enclosed foyer. Use the sound-system coverage and intelligibility guide to turn the room walk into audience zones, speaker positions, and test locations.
Increase the direct-to-reverberant advantage
The useful design goal is not to overpower the room everywhere. It is to deliver enough direct speech to each listener before reflected energy and background noise obscure its modulation. Aim loudspeakers at people rather than ceilings, rear walls, glass, or empty architecture. Choose vertical and horizontal coverage that fits the audience geometry, keep unnecessary overlap out of reflective boundaries, and lower a cabinet if its pattern otherwise clears the front seats and excites the far wall.
A distributed system can place smaller sources closer to listeners and operate each zone at less level than one distant loudspeaker trying to cover the entire space. That can improve consistency and reduce energy sent into unused surfaces, but only when coverage edges and arrival times are managed. More cabinets without a plan can create comb filtering, competing localizations, and additional late energy. Prediction tools help, but onsite listening and measurement remain necessary because temporary drape, staging, seating, and people change the room.
Capture speech closely and control open microphones
Clarity begins before the loudspeaker. Keep a handheld, headworn, lavalier, or gooseneck microphone at a stable and appropriate distance from the talker. A close microphone captures more voice relative to room sound and permits useful level with less gain. Shure’s conference-miking guidance notes that distant microphones can sound hollow and indistinct, recommends close placement for conferencing, and warns that overhead audience miking becomes problematic when sound reinforcement is involved.
Match the microphone to presentation style. A podium gooseneck suits a fixed reader; a headworn microphone keeps the capsule position consistent for a mobile presenter; a handheld question microphone can be brought close to each audience speaker. Train users before doors open. Mute unused channels or use a carefully commissioned automixer so the system does not continually add room pickup. The gain structure and feedback prevention resource explains why microphone geometry and the number of open paths affect usable gain.
Add delay fills only where the main system loses
A delay fill should solve a defined coverage gap: a deep room, balcony, under-balcony area, side section, foyer, or other zone that cannot receive adequate direct sound from the main system. Place the fill near the listeners it serves and aim it only across that zone. Establish its level by comparison with the main arrival, not by making the fill obviously louder. If listeners turn toward the fill instead of the stage, its level, timing, placement, or spectral balance may be drawing too much attention.
Set delay from measured arrival-time difference between the acoustic reference and the fill, then listen around the transition. Physical distance provides a starting estimate, but loudspeaker processing, driver path, mounting position, and reflective arrivals can change the result. Check several seats before and after the coverage boundary with speech and an analysis signal. The related event speaker placement guide covers safe positioning, sightlines, cable paths, and practical zone documentation.
Use processing to preserve speech, not decorate it
Start with correct source placement, loudspeaker aiming, and gain structure. High-pass microphones where appropriate to reduce handling noise, stage rumble, and low-frequency energy that consumes headroom without improving word recognition. Correct a clearly identified loudspeaker or room interaction with restrained equalization, but do not expect broad EQ to remove reverberation. Reflections are time-domain energy; a graphic curve cannot distinguish a direct consonant from the same consonant returning later.
Compression can steady a presenter with variable technique, yet aggressive settings may raise room noise and breaths between phrases. Limiters should protect the system without flattening every transient. Maintain headroom for emphasis and audience questions, and build separate speech and music scenes when their requirements differ. The digital mixer guide explains routing, recall, buses, and recovery planning for systems with mains, fills, recording, streaming, and assisted-listening feeds.
Measure STI with its assumptions attached
IEC 60268-16:2020, incorporating its July 2025 corrigendum, defines the Speech Transmission Index model, test signals, and measurement and prediction methods. The IEC also states that the document does not set certification criteria for every transmission channel and identifies limitations involving echo, fluctuating noise, privacy, and digitally compressed voice paths. An STI number is therefore evidence about a defined test condition, not a permanent grade for every talker, crowd, seat, or program.
Measure representative front, middle, rear, side, balcony, under-balcony, and accessibility positions at a realistic system level and with realistic background conditions. Record the source, device, method, room state, audience state, processing, position, and time. Repeat after material changes instead of comparing unlabeled numbers. A listening panel should still test live speech, unfamiliar names, dates, and safety announcements because a technically valid measurement does not replace operational rehearsal.
Plan for the listeners most affected by poor clarity
A peer-reviewed classroom-like experiment by Klatte, Lachmann, and Meis compared shorter and longer reverberation conditions with background sounds. The combination of noise and longer reverberation increased speech-perception difficulty across age groups, while children showed particular vulnerability in the tested tasks. An event venue is not a virtual classroom, so those results cannot predict an individual guest’s experience or establish a universal event threshold. They do support a cautious planning principle: background noise and reverberation should be evaluated together, and listener needs are not identical.
Provide clear sightlines to presenters, captions or text where appropriate, a quiet adjacent area when feasible, and a tested assisted-listening or interpretation path when the event requires one. Do not assume extra volume solves access. For conferences, civic programs, and panels, corporate event AV support can combine microphone planning, distributed coverage, rehearsal, and backup routing in one production brief.
Commission the system as an occupied event
Load the final mixer scene, place furniture and drape, power displays and HVAC, open expected doors, and test with the actual microphones. Walk every audience zone while a second person speaks naturally. Listen for repeated syllables, hollow transitions, level jumps, feedback risk, masking from music or service activity, and fills that arrive as separate echoes. Save measurements and settings, label every output, and rehearse a fallback if a fill, network link, microphone, or processing path fails.
The practical conclusion is to design for direct speech at every seat: map reverberation and noise, aim within audience boundaries, keep microphones close, add measured delay fills only where needed, preserve headroom, and verify several occupied positions with listening plus documented STI or reverberation tests when appropriate. Blue Ridge Sound provides event-production guidance, not medical treatment, hearing assessment, accessibility certification, architectural-acoustics certification, or individualized safety advice.
Research & technical references 4
These outside sources informed this article and offer useful primary or authoritative background. See our editorial standards.
- IEC 60268-16:2020: Objective Rating of Speech Intelligibility by STIwebstore.iec.ch
- ISO 3382-2:2008: Reverberation Time in Ordinary Roomsiso.org
- PubMed: Effects of Noise and Reverberation on Speech Perception and Listening Comprehensionpubmed.ncbi.nlm.nih.gov
- Shure: Conference Miking—Seven Spaces and Seven Solutionsshure.com