Free online audio spectrum analyzer with real-time visualization of frequency spectrum and waveform. Supports microphone input and file upload, FFT spectrum analysis, frequency/amplitude display. Pure frontend Web Audio API processing.
Zero Dependencies · Works Offline🎤 Audio Input
📈 Spectrum
〰️ Waveform
📖 What Can the Online Spectrum Analyzer Do?
The Online Spectrum Analyzer is a real-time audio analysis tool based on the Web Audio API. It uses Fast Fourier Transform (FFT) to convert audio signals from the time domain to the frequency domain, visually displaying the frequency components and amplitude distribution of audio. It supports real-time microphone input and audio file upload, making it suitable for audio debugging, instrument tuning, acoustic analysis, and more.
Key Features
- Real-time Spectrum Analysis: FFT algorithm calculates frequency distribution in real-time with visual display
- Waveform Display: Real-time time-domain waveform rendering to observe signal changes
- Microphone Input: Real-time analysis of environmental sounds via browser microphone
- File Analysis: Upload MP3/WAV/OGG and other audio files for spectrum analysis
- Adjustable Parameters: FFT size and smoothing coefficient can be tuned for different analysis needs
- Frequency Statistics: Real-time display of peak frequency, peak amplitude, and sample rate
How to Use
- Select input method: Click "Microphone" or upload an audio file
- Adjust FFT size: Larger values give higher frequency resolution but slower updates
- Adjust smoothing: 0 = instant response, closer to 1 = smoother but with latency
- Observe real-time changes in the spectrum and waveform displays
- Check the statistics for peak frequency and peak amplitude
Use Cases
Scenario 1: Music Production
Analyze instrument timbre characteristics, identify frequency peaks, and assist with EQ adjustment and mixing decisions.
Scenario 2: Acoustic Debugging
Detect room resonance frequencies, analyze noise spectra, and assist with acoustic treatment design.
Scenario 3: Education
Visually understand Fourier transform principles, observe timbre differences across instruments, and learn acoustic fundamentals.
Technical Background
Spectrum analysis is based on the Fourier transform, which decomposes complex signals into sinusoidal components of different frequencies. The Web Audio API's AnalyserNode provides getByteFrequencyData (frequency domain data) and getByteTimeDomainData (time domain data) methods for retrieving spectrum and waveform data respectively. The FFT size determines frequency resolution: at fftSize=2048 with a 44100Hz sample rate, the frequency resolution is approximately 21.5Hz.
📖 FAQ
What is an online spectrum analyzer?
An online spectrum analyzer is a tool that analyzes audio frequency components in real-time through a browser. It uses the Fast Fourier Transform (FFT) algorithm to convert audio signals from the time domain to the frequency domain, visually displaying the amplitude distribution of each frequency to help users understand the frequency characteristics of audio.
What audio input methods are supported?
This tool supports two input methods: 1) Real-time microphone input — obtains microphone access through the browser to analyze environmental sounds or instrument performances in real-time; 2) Audio file upload — supports common formats like MP3, WAV, OGG, and FLAC for analyzing pre-recorded audio files.
What is FFT (Fast Fourier Transform)?
FFT is an algorithm for efficiently computing the Discrete Fourier Transform. It decomposes time-domain signals (waveforms varying over time) into frequency-domain signals (amplitudes of each frequency component), and is the core algorithm of spectrum analysis. FFT precision depends on the sample rate and window size (fftSize) — larger windows give higher frequency resolution but lower time resolution.
What do the colors in the spectrum represent?
The colors in the spectrum represent the amplitude (volume) of each frequency. Typically: blue/dark colors indicate low amplitude (quiet), green/yellow indicate medium amplitude, and red/bright colors indicate high amplitude (loud). Color mapping can be adjusted in settings.
Is audio data uploaded to a server?
No. All audio analysis is performed entirely in your browser using the Web Audio API's AnalyserNode. Whether using microphone input or file upload, audio data never leaves your device.