Your noise floor is the level your microphone picks up when nothing is happening — the constant hiss, hum and rumble underneath everything you record. It comes from the room itself (room noise from HVAC, traffic, computer fans, air conditioning), the electrical environment (mains hum, ground loops, RF interference), and the microphone and preamp themselves (microphone noise, also called self-noise or equivalent input noise). Using this background noise detector as a quick quiet room test before a recording session lets you catch problems — a loud fan, an HVAC rumble, electrical hum — before they ruin a take. The lower your noise floor relative to your voice, the cleaner and more professional your recordings, podcasts, or video calls sound. A high noise floor is one of the most common reasons home recordings sound "amateur," even with a good microphone.
This tool measures the floor in dBFS — decibels below digital full scale. While you stay quiet it tracks the steady level and, if you start talking, it detects the jump and pauses so your voice doesn’t pollute the reading. It also runs an FFT (Fast Fourier Transform) to spot tonal noise — narrow spikes at specific frequencies that stand out from the broadband hiss — and names the usual suspects. Because it uses the Web Audio API with noise suppression and auto-gain control deliberately disabled, the reading reflects the true raw signal rather than what your OS has already filtered.
Common noise culprits and fixes
- Mains hum (50 or 60 Hz + harmonics) — a sharp spike at your country’s mains frequency (60 Hz in the Americas, 50 Hz most elsewhere) usually means a ground loop, unbalanced cable, or interference. Try a different outlet, a balanced cable, or moving the mic away from power supplies and screens.
- Low-frequency rumble (below ~120 Hz) — HVAC, traffic, footsteps, or desk vibration. Use a shock mount, a high-pass filter, and isolate the mic stand.
- Mid/high whine — computer fans, coil whine, or hard drives. Move the mic away from the machine, or the machine away from the mic.
- Broadband hiss with no spikes — usually mic/preamp self-noise or too much gain. A quieter mic, less gain, or getting closer (so you need less gain) all help.
How this differs from related tools
This is the quick "how noisy is my space" check with culprit identification — ideal before starting a recording session, a podcast episode, or a video call. For a full per-condition profile (noise floor, speech level, SNR, dynamic range) use the Mic Sensitivity Analyzer; for a detailed spectral/per-band noise-floor breakdown use the Noise Floor Analyzer. If you specifically want to pinpoint and measure 50 or 60 Hz mains hum in detail, the hum frequency detector zooms in on that problem exclusively.
What’s a good noise floor?
It depends on your gain, but as a rough guide for this dBFS reading: below −60 dBFS is quiet, −60 to −48 is moderate, above −48 is noisy. What matters most is the gap to your voice — for clean speech you want the noise floor at least 25–30 dB below your normal speaking level.
Why dBFS instead of real decibels (dB SPL)?
A browser can’t read calibrated sound-pressure levels, so this measures the digital signal level (dBFS) rather than room loudness in dB SPL. That’s exactly what you need to judge your recording chain’s noise — but it isn’t a substitute for a calibrated SPL meter measuring how loud the room is to your ears.
Why does it pause when I talk?
The noise floor is the level when you’re not making sound. If the level jumps well above the running floor, the tool assumes that’s you (or another sound) and excludes those moments from the floor statistics, so your voice doesn’t inflate the reading. Stay quiet for the most accurate result.
It detected 50/60 Hz hum — what do I do?
A spike at 50 or 60 Hz (and its harmonics like 100/120 Hz) is electrical hum, usually from a ground loop, an unbalanced cable, or interference from power supplies and screens. Try a different power outlet, a balanced (XLR) cable, a ground-loop isolator, and keeping the mic and its cable away from power adapters, laptops, and monitors.
Is the "dominant tone" always a problem?
Not necessarily — it just flags the strongest narrow-band component in your noise. If it’s well below your floor it’s harmless. If it’s prominent (a clear fan whine or hum), it’s worth chasing down because tonal noise is more noticeable and harder to mask than broadband hiss.
My floor is high but there are no spikes — why?
That’s broadband noise, typically microphone/preamp self-noise or simply too much gain amplifying hiss. Lower your input gain (and get closer so you still get a strong signal), or use a quieter microphone. The
Mic Gain Level Meter helps you set gain with headroom.
Does noise suppression affect the reading?
The tool requests the raw signal with noise suppression and auto-gain off so you see the true floor. If your OS forces noise suppression that can’t be disabled, the reading will look artificially clean — turn off microphone "enhancements" in your system settings for an honest measurement.
Is any audio recorded?
No. The signal is analyzed in real time to compute level statistics and spot tonal peaks only; nothing is recorded, saved, or transmitted. The microphone is released when you press Stop or close the tab.
What noise floor do I need for a good podcast or voice recording?
Most podcasters and voice-over producers aim for a noise floor below −60 dBFS (relative to mic gain) with at least 25–30 dB of separation between the floor and their speaking level. In treated home studio conditions this is achievable with a decent dynamic or condenser mic. If your floor reads above −48 dBFS, acoustic treatment, a higher-quality microphone, or moving away from noise sources will make the biggest difference.
Can I use this to check my room before a video call or online meeting?
Yes — that is one of the most practical uses. Run it before your call, stay quiet for 10–15 seconds, and check the verdict. A "Noisy" reading means your colleagues will hear background hum or hiss even when you’re not talking. The dominant-tone readout can tell you whether the culprit is HVAC rumble, electrical hum, or a fan, so you can address it before joining the meeting.
What is signal-to-noise ratio (SNR) and how does this tool relate to it?
SNR is the difference in level between your desired signal (your voice) and the noise floor — a higher SNR means cleaner audio. This tool measures only the noise floor half of that equation. To measure the full SNR including your speech level, use the
Mic Sensitivity Analyzer, which profiles both the floor and your speaking level together and reports the gap between them.