Tuned to 94.7 MHz. Signal strength 0 percent.
Signal strength 000
Standby
About Spirit Box
Spirit Box
Spirit box devices work by sweeping a radio dial fast enough that no station holds, leaving fragments of whatever the receiver passes over. This one is fully synthesised: a static bed generated by an AudioWorklet, a formant voice built from a sawtooth glottal source and three bandpass resonances, and a receiver chain of filtering, saturation and compression that both pass through together.
Nothing here is a recording and nothing is transmitted. The voice does not say words - it produces syllabic motion, because an unresolvable almost-voice is more interesting than a clear one and honest about not being a real transmission. Sweep rate, static level, bandwidth and instability are all under your control.
How to use Spirit Box
- Put on headphones. The static bed and the voice share the same frequency range, and small phone or laptop speakers lose most of the detail that makes the sweep interesting.
- Press Initialize signal. Browsers do not allow a page to make sound until you ask it to, so nothing plays before this.
- Set the Scan control. A faster sweep holds each frequency for less time, so fragments become shorter and more broken; a slower sweep lets each one run longer.
- Balance Static against the transmission controls. A high static bed with rare, weak transmissions sounds like a classic hardware sweep; turning transmissions up makes the voice more present.
- Hold the dial to tune by hand. While held, the sweep stops and you choose the frequency yourself, which is useful for lingering on one part of the band.
- Optionally load a local audio file as the transmission voice. It is decoded in your browser and passed through the same receiver chain; it is never uploaded.
Tips
- Sessions work best in a quiet room at a moderate volume. Loud static is tiring, and fatigue makes everyone hear more in noise.
- If you want to review a session properly, record it with the EVP Recorder on a second device, or use Ghost Box, which logs what the signal did and when.
Questions
What is a spirit box?
A spirit box, also called a ghost box, is a radio receiver modified to sweep continuously across the AM or FM band without stopping on any station. The result is a stream of static broken by split-second fragments of speech and music. Frank Sumption’s “Frank’s Box” in the early 2000s popularised the idea, and commercial units such as the P-SB7 followed.
Does this spirit box tune real radio stations?
No. Everything you hear is synthesised in your browser: the static, the receiver colouring and the voice. Phones and computers have no FM tuner the web can reach. If you want genuine broadcast fragments, Ghost Radio scans real internet radio stations instead.
Can a spirit box communicate with spirits?
There is no evidence that it can. The human brain is very good at finding speech in noise — a form of auditory pareidolia — and rapid fragments of sound are exactly the material it works best on. This tool is built to make that experience vivid while being clear about where the sound comes from.
What is the difference between Spirit Box and Ghost Box on this site?
They share the same sweep engine. Ghost Box adds session logging: live analysis of the signal, timestamped events and markers, and an export you can review afterwards.
Why can I not hear anything on my iPhone?
Check the ring/silent switch. Safari can route web audio through the ringer, so silent mode mutes it. Then make sure you have pressed Initialize signal and that the volume is up.
Is anything recorded or uploaded?
No. The audio is generated on your device and nothing is sent anywhere. There is no account and no install.
This is an instrument and a sound tool, provided for entertainment and experiment. It describes what it measures and does not identify the cause of anything it shows.
Related tools
Guides
Also available as an Android app: Spirit Box
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