The live meter below is preset to Visualization → Spectrum with A-weighting for perceived loudness. It updates live alongside level and waveform views.
What a Frequency Analyzer Does
A decibel value alone says how loud but not what kind of sound. A frequency analyzer breaks the signal into frequency bands and shows energy per band — typically as a bar graph with low frequencies (Hz) on the left and high frequencies on the right. You can see whether noise is dominated by bass rumble (~60–120 Hz), mid-range speech (~300–3000 Hz), or high-frequency hiss.
This tool's analyzer runs via the Web Audio AnalyserNode FFT (2048-point), yielding ~1024 frequency
bins up to the Nyquist frequency (half the sample rate). Bars are grouped for readability. See
Methodology — Spectrum for the FFT and weighting details.
Example spectrum shape
Illustrative. Live spectrum reflects your microphone's frequency response — phone mics often under-report deep bass.
How to Use It Here
- Click Start Measuring on the meter.
- In the Visualization card, choose the Spectrum tab. Keep the source and distance stable.
- Compare A / C / Z weighting — A shapes toward speech, C keeps more bass, Z is flat (see Weighting guide).
- Use Fast for fluctuating sound, Slow to smooth the view. Watch where the tallest bars sit.
Reading the Spectrum
- Bass (~20–250 Hz): traffic rumble, subwoofers, engines, HVAC hum. Tall left-side bars.
- Mids (~250–4000 Hz): speech, most appliances, broadband noise. Central bars dominate for typical rooms.
- Treble (~4–16 kHz): hiss, cymbals, high-pitched motors. Right-side bars; phone mics capture this better than bass.
- If dBC is much higher than dBA for the same sound, the spectrum confirms bass dominance — check with dBC Meter.
Limitations
- Phone microphones are speech-optimized: they under-report deep bass vs. a lab mic. A flat-looking low end does not prove there is no bass.
- Frequency resolution is limited by the 2048-point FFT (~23 Hz per bin at 48 kHz). Fine tonal detail is approximate.
- Room reflections and distance reshape the spectrum just as they reshape overall dB. Measure where people actually are.
- For certified spectral analysis use calibrated instrumentation. Here, trends and comparisons are reliable; absolute band levels are estimates.
FAQ — Frequency Analyzer
What is a frequency analyzer?
What is the difference between frequency analyzer and spectrum analyzer?
Can I use it to tune speakers or find hum?
What frequency range does it cover?
Related: Audio Spectrum Analyzer · dBA Meter · dBC Meter · Leq Meter · Methodology