See the frequencies inside any sound. This free frequency analyzer is a real-time audio spectrum analyzer: start your microphone to watch the FFT spectrum and a scrolling spectrogram live, or open an audio file (MP3, WAV, M4A, OGG or FLAC) to analyse it. It shows the peak frequency with its musical note, the five strongest frequencies, and lets you freeze, hold peaks and save an image.
Frequency Analyzer
See the frequencies in any sound: start the microphone for a live spectrum, or open an audio file to analyse it.
Microphone off. Sound is analysed in your browser; nothing is recorded or uploaded.
Strongest frequencies
- Start the microphone or open a file.
Settings
Levels are relative to your device's full scale (dBFS), not calibrated sound pressure. Phone and laptop microphones pick up little below about 50–100 Hz, so deep bass can look weaker than it is. Files are decoded on your device and are not uploaded.
Related Tools
- Online Tone Generator
Play test tones and sweeps to analyse speakers and rooms.
- Sound Decibel Meter
Measure how loud a sound is in dB.
- Background Noise Test
Find out if a room is quiet enough, and where the noise comes from.
- Microphone Test
Make sure your mic works before you analyse.
- Online Hearing Test
Check which frequencies you can hear.
- Audio Wavelength Calculator
Turn a frequency into its wavelength, handy for room modes.
How to Use the Frequency Analyzer
- Press Start microphone and allow access, then play, sing or speak near the microphone. Or press Analyse an audio file and choose a file.
- Read the peak frequency and nearest note at the top, and the strongest frequencies list below the graphs.
- Use Freeze to hold the picture, and turn on Peak hold in Settings to keep the highest level reached at each frequency.
- For a file, the spectrum shows the average of the whole file and the spectrogram shows it from start to end; press Play file to watch it live.
- Press Save image to download the graphs as a PNG.
Spectrum vs Spectrogram
The spectrum shows how strong each frequency is right now: frequency in hertz across the bottom, level in decibels up the side. Peaks are the tones in the sound. The spectrogram adds time: it scrolls from right to left, with frequency going up and brighter colours meaning louder, so you can see melodies, speech patterns, beeps and hums over time.
A logarithmic frequency axis gives each octave the same width, which matches how we hear pitch; switch to linear to inspect high frequencies in detail. The level axis is in decibels, which are logarithmic too (why decibels are logarithmic), and frequency and level are different things: dB vs Hz.
Reading the Results
- Peak frequency is the strongest frequency, refined between FFT bins for accuracy, with the nearest note and how many cents sharp or flat it is.
- Strongest frequencies lists up to five separate peaks. For a musical note, the lowest strong peak is usually the fundamental and the others are its harmonics at 2×, 3× and 4× the frequency.
- Level is in dBFS, relative to the loudest signal your device can handle (0 dBFS), not the loudness in the room. See dB vs dBFS and the decibel units guide; loudness in the room is sound pressure level, which the sound decibel meter measures.
FFT Size and Frequency Resolution
The analyzer uses a Fast Fourier Transform (FFT). A bigger FFT splits the spectrum into finer steps but needs a longer slice of sound, so it reacts more slowly.
| FFT size | Step at 48 kHz | Time slice | Best for |
|---|---|---|---|
| 2,048 | 23.4 Hz | 43 ms | Fast-changing sounds, speech |
| 8,192 (default) | 5.9 Hz | 171 ms | Most uses: notes, hum, voices |
| 32,768 | 1.5 Hz | 683 ms | Separating very close or very low tones |
What You Can Do With It
- Find a hum or buzz: a peak at 50 Hz or 60 Hz (and multiples) means mains hum; the background noise test also detects it.
- Track down feedback: the ringing frequency shows as a tall, narrow peak you can cut with an equaliser.
- Check room resonance and speakers: play a slow sweep from the tone generator and watch for peaks and dips.
- Tune and check pitch: see the note and cents of an instrument or your voice.
- Inspect recordings: open a file to spot rumble, hiss or missing high frequencies before you publish, or to find where a noise sits (see podcast room noise).
Accuracy and Limitations
Frequency readings are precise, because they depend only on the sample rate and the FFT. Levels are relative, and your microphone shapes what you see: phone and laptop microphones pick up little below about 50–100 Hz and often roll off the highest frequencies, so deep bass can look weaker than it is. The highest frequency shown is limited to half the sample rate. For level accuracy and calibration, see online decibel meter accuracy, and to measure how loud a sound really is, follow how to measure decibels.
Frequently Asked Questions
Is a frequency analyzer the same as a spectrum analyzer?
For audio, yes: both show how much energy a sound has at each frequency. “Spectrum analyzer” is the usual name for the graph, and an FFT analyzer is a spectrum analyzer that uses the Fast Fourier Transform.
How do I find the frequency of a sound?
Start the microphone and play the sound near it. The peak frequency and nearest note appear at the top; for sounds with several tones, check the strongest frequencies list.
Which audio files can I analyse?
Any format your browser can decode, usually MP3, WAV, M4A/AAC, OGG and FLAC, up to 200 MB. Files are analysed on your device and never uploaded.
Why can’t I see anything below 50 Hz?
Most phone and laptop microphones barely capture deep bass. Use an external microphone, or analyse a recording made with better equipment.