Spectrogram online and spectrum analyzer
This spectrum analyzer shows which frequencies make up the sound reaching your microphone. At the top are the bars: each one is a frequency band and its height is how strong the sound is there, in dB. Below is the spectrogram, with the last 8 seconds scrolling down: frequency runs from left to right and color shows strength (dark is silence, yellow is loud).
How to use it
- Tap Turn on microphone and allow access when your browser asks.
- Make the sound you want to analyze: a note, your voice, a whistle, an engine hum.
- Read the peak at the top: strongest frequency, nearest note and cents.
- Tap, drag or hover over the graph to see the frequency, note and level at that point.
- Use Freeze to stop the image and Resume to go back to live.
Help and explanations
The strongest frequency is shown in Hz, with the note and cents. Tap or hover over the graph to read any point, and freeze the display to examine it at your own pace. Everything runs on your device, without uploading any audio.
How to read the spectrum and spectrogram
An instrument note shows up as a ladder of lines: the fundamental plus harmonics at 2, 3 and 4 times its frequency. A whistle is almost a single line; hiss and wind spread color across a wide band. On the logarithmic scale, the default, every octave takes up the same space, like on a piano, and the purple marks at the top show the Cs. The linear scale gives more room to the high frequencies.
Why the peak isn't always the note
The peak is the frequency with the most energy, and in the voice and many instruments that's a harmonic, not the fundamental: singing an A3 (220 Hz) on an open vowel, the peak may land on 440 or 660 Hz. For the note, use the voice tuner or the chromatic tuner, which look for the fundamental.
Resolution, range and smoothing
With an 8192-point FFT and the microphone at 48 kHz, each bin is 5.9 Hz wide, enough to separate neighboring notes above about 100 Hz. With 16384 the low end gets sharper and the image reacts more slowly; with 2048 it's faster and blurrier. The dB range changes the color contrast.
Tips
- To see an instrument's harmonics, bring the microphone close and play a long note.
- Freeze right after a short sound (a clap, a finger snap) to measure it calmly.
- Phone microphones usually cut off below about 50 Hz and above about 15 kHz: what's missing there may be down to the mic.
- Use the tone generator on another device to check the reading against a known frequency.
Frequently asked questions
What is a spectrogram?
It's a picture of sound where one axis is time, the other is frequency and color is intensity. Speech, singing and music turn into patterns you can read.
What's the difference between a spectrum analyzer and a spectrogram?
A spectrum analyzer shows the frequencies at a single instant (the bars); a spectrogram stacks those instants and shows the last few seconds (the waterfall). Here both share the same axis.
Can I find the frequency of a sound?
Yes. The peak shows the strongest frequency in Hz, and tapping the graph shows the frequency at any point. For the note of a voice or instrument, a tuner is more reliable.
Can I see the spectrogram of an audio file?
This tool analyzes live sound from the microphone. For a file, play it near the mic or open it in an editor like Audacity, which has a spectrogram view.
Can I use it as a car audio RTA?
It gives you an idea of where the bass, mids and treble are, but a phone mic is neither flat nor calibrated. To EQ a car or venue sound system accurately, use a measurement microphone and a dedicated RTA.
Why is there a peak at 60 Hz?
In North America the power grid runs at 60 Hz (50 Hz in the UK, Europe and Australia), and its hum, with harmonics at 120 and 180 Hz (or 100 and 150 Hz), shows up with an ungrounded cable, a noisy power supply or equipment near the microphone.