What is a Good Noise Floor for a Meeting Room?

Why Noise Floor Matters for Conference Calls

Background noise affects conference calls differently than it affects people in the room:

• You can tune it out. After a few minutes in a room, your brain filters out constant sounds like HVAC hum. You stop noticing it.
• Remote participants can't. They hear what the microphone captures. The mic doesn't filter anything - it picks up speech and noise equally.
• Noise competes with speech. When background noise is loud, remote participants have to turn up their volume. This amplifies both speech and noise, making it harder to follow.
• Noise causes fatigue. Straining to separate speech from background noise for an hour-long meeting is exhausting. People disengage.

This is why a room can "feel" quiet to people sitting in it but sound noisy to remote participants.

Noise Levels and What They Mean

Background noise is measured in decibels (dB SPL, with a calibrated meter). Here's what different levels mean for conference rooms:

For reference: common sound levels

• 20 dB: Quiet recording studio, rustling leaves
• 30 dB: Whisper, quiet library
• 40 dB: Quiet office, residential neighborhood
• 50 dB: Moderate rainfall, normal conversation at 1 meter
• 60 dB: Normal conversation at arm's length, busy office

NC ratings

You may also see noise specified as NC (Noise Criteria) ratings. NC accounts for how noise is distributed across frequencies. Roughly:

• NC-25 to NC-30: Very quiet, ideal for conference rooms
• NC-30 to NC-35: Good, standard target for meeting spaces
• NC-35 to NC-40: Acceptable, typical open office background
• NC-40+: Too noisy for effective conferencing

Common Noise Sources

HVAC systems (most common)

Heating, ventilation, and air conditioning create constant low-frequency rumble. Sources include:

• Air rushing through vents: Faster airflow = more noise.
• Ductwork vibration: Poorly secured ducts rattle and hum.
• Equipment rooms: Air handlers and compressors near or above the room.
• Return air paths: Open ceiling plenums transmit noise between rooms.

HVAC noise is insidious because it's constant. You stop noticing it, but it's always there on the call.

Hallway and adjacent spaces

• Conversations: People talking outside the door or in adjacent rooms.
• Footsteps: Hard floors in hallways amplify foot traffic.
• Doors: Opening and closing doors, especially without soft-close hardware.
• Open office noise: If walls don't go to the ceiling deck, open office sound travels over.

Electronic equipment

• Projectors: Cooling fans in projectors can be surprisingly loud.
• Computers: Desktop PCs with fans, especially under heavy load.
• Displays: Some large displays have cooling fans.
• Network equipment: Switches or routers in the room.

External noise

• Traffic: Cars, trucks, buses - especially problematic near windows.
• Construction: Temporary but can make rooms unusable.
• Aircraft: Near flight paths.
• Weather: Rain on windows, wind.

How to Assess Your Room

Simple listening test

1. Sit in the room with the door closed and HVAC running normally.
2. Close your eyes and focus on what you hear.
3. Note any constant sounds (hum, rush of air) and intermittent sounds (hallway, outside).

What to listen for:

• Can you hear air moving? That's HVAC noise the mic will pick up.
• Can you hear conversations outside? Remote participants will hear them too.
• Is there a constant hum or buzz? Check for electronic sources.
• Does noise level change? HVAC cycling on/off, or intermittent traffic?

Phone app measurement

Many smartphone apps measure sound levels in dB. They're not calibrated like professional meters, but they're useful for comparison:

• Measure with HVAC running normally (not during a quiet period).
• Measure for at least 30 seconds to catch fluctuations.
• Note both the average and the peaks.

How to Reduce Background Noise

HVAC noise

• Reduce airflow during calls: If you have zone control, lower the fan speed or close vents partially during important meetings.
• Add duct silencers: Inline silencers in the ductwork reduce air rush noise.
• Seal gaps: Check for gaps around vents where noise escapes. Acoustic sealant helps.
• Add diffusers: Replace standard vents with low-velocity diffusers that spread air more quietly.
• Relocate equipment: If possible, move air handlers or compressors away from the room.

Hallway and adjacent noise

• Door seals: Add weatherstripping and door sweeps. Sound travels through gaps.
• Solid-core doors: Replace hollow-core doors with solid-core for better isolation.
• Automatic door closers: Soft-close mechanisms prevent slamming.
• Extend walls: If walls stop at the drop ceiling, extend them to the deck above.
• Add mass: A second layer of drywall with damping compound significantly improves wall isolation.

Equipment noise

• Move it out: Put projectors, PCs, and network gear in an adjacent closet or rack room.
• Use quiet models: When replacing equipment, check noise specifications.
• Isolate vibration: Put equipment on isolation pads to reduce transmitted hum.

External noise

• Heavy curtains: Thick, floor-to-ceiling curtains absorb some external noise.
• Secondary glazing: Adding a second layer of glass to windows significantly reduces traffic noise.
• Seal window frames: Check for air gaps around windows where sound enters.
• Choose rooms wisely: For critical meetings, use interior rooms away from street-facing windows.