--- title: "Spectrum Analyzer Online - Audio FFT Tool | CanDoYa" description: "Use a free online spectrum analyzer for audio files or your microphone. View live FFT frequencies and readable band levels privately in your browser." url: https://candoya.com/tools/spectrum-analyzer/ locale: en type: browser-tool --- # Spectrum Analyzer Online Category: Social & Creator ## What does an audio spectrum analyzer show? An audio spectrum analyzer shows how strongly different frequencies are present in a sound. Play a local audio file or use your microphone to view a live FFT display from bass to treble. A text readout also reports the strongest frequency, spectral center, and seven practical frequency bands. The graph uses a logarithmic frequency scale, so the octaves where human hearing is most sensitive get useful room instead of being squeezed against the left edge. Adjust the FFT size for the tradeoff you need: larger transforms separate nearby frequencies more clearly, while smaller transforms respond faster to short changes. The seven-band table turns the moving graph into a readable snapshot. Sub bass covers 20 to 60 Hz, bass reaches 250 Hz, and the midrange is divided around common vocal and instrument regions. These are practical production labels, not hard acoustic boundaries. ## How to use it 1. **Choose an audio source** - Drop or choose an audio file, play the sample tones, or start live microphone input. 2. **Start the signal** - Press play for a file, or allow microphone access when your browser asks. 3. **Read the spectrum** - Watch the logarithmic bars and compare the strongest frequency, spectral center, peak strength, and seven band levels. 4. **Adjust the response** - Choose a larger FFT for finer frequency separation or change smoothing for steadier or faster movement. ## Who it's for - **Musicians and producers** can spot bass buildup, harsh upper mids, or missing high-frequency energy while auditioning a mix. - **Podcasters and voice creators** can inspect room rumble, vocal presence, and bright sibilant energy before recording. - **Students** can connect audible tones with their measured frequency and see how harmonics appear above a fundamental. - **Audio troubleshooters** can compare a local file with live microphone input without installing a desktop analyzer. ## Expert note At a 48 kHz sample rate, a 4096-point FFT spaces bins about 11.7 Hz apart. That does not mean every reading is accurate to 11.7 Hz: windowing, leakage, noise, room response, microphone coloration, and the signal's duration still affect what the display reports. ## Frequently asked questions ### Is my audio uploaded or recorded? No. Audio files are decoded and analyzed inside your browser tab. Microphone input is routed to the analyzer in memory and is never recorded or saved. The page only asks for microphone permission when you choose that source, and stopping the microphone releases its media track. ### Is this online spectrum analyzer free? Yes. You can analyze audio files, use live microphone input, change the FFT resolution and smoothing, copy the readable results, and replay the sample without an account, payment, or watermark. Processing uses browser APIs on your own device. ### What file and frequency limits apply? The file limit is 150 MB, and playable formats depend on the codecs built into your browser and operating system. The graph covers 20 Hz to 20 kHz when the source sample rate permits it. A 44.1 kHz source has a theoretical upper limit of 22.05 kHz. ### Can I use my microphone as a live frequency analyzer? Yes, in a current browser on a secure HTTPS page. Choose Use microphone and approve access. Browser audio processing options are disabled where supported so the spectrum is less altered, but your microphone, room, and device can still color the measurement. ### What FFT size should I choose? Start with 4096 for a useful balance. A larger FFT such as 8192 gives narrower frequency bins and can separate steady nearby tones better, but responds more slowly. A smaller FFT such as 512 or 1024 follows quick transients more closely but groups more frequencies together. ### Why does the strongest frequency move around? Real audio contains many simultaneous frequencies, and the strongest FFT bin can change from frame to frame. Smoothing steadies the display, while a larger FFT can improve separation. Background noise, musical harmonics, microphone response, and spectral leakage also affect which bin appears strongest. ### Is this a calibrated sound level meter? No. The percentages are relative Web Audio magnitudes for comparing frequency regions, not calibrated dB SPL measurements. Accurate sound pressure readings require a calibrated microphone, known gain, and measurement software designed around that hardware. ## Related tools - [Audio Waveform Image](https://candoya.com/tools/audio-waveform-image/) - [Guitar Tuner](https://candoya.com/tools/guitar-tuner/) - [Tone Generator](https://candoya.com/tools/tone-generator/) - [Audio Normalizer](https://candoya.com/tools/audio-normalizer/) - [Audio Trimmer](https://candoya.com/tools/audio-trimmer/) --- *Markdown edition of , published for AI agents and other automated readers. Index of key pages: .*