THRESHOLD: Spirit Box & EVP

THRESHOLD is a spirit box, EVP recorder and paranormal field kit, built as one serious instrument for ghost hunting. It sweeps noise and real recorded voices, listens to the room, writes down the words a speech model hears, and keeps every sensor reading on the same clock as the sound. When something happens, you have the moment, the audio and every reading around it.

YOU NEVER HAVE TO BE RECORDING

The rig always holds the last sixty seconds, and keeps running with the screen off in your pocket. Hear it first, then save it.

GRAB saves the 15, 30 or 60 seconds before you pressed it, from the notification too.
MARK drops a mark on the timeline; hold it to name what happened.
REC records until you stop; left alone, the screen goes dark so it won't light the room.

Every capture keeps what you heard and a clean copy from before the effects, so a heavy reverb never ruins the evidence.

THE SOUND

Nine layerable sources: WHITE, PINK and BROWN noise, HISS, GRAIN, DRONE, FORMANT, and VOICE and REVERSE, which sweep real recorded human speech and start every grain at a word boundary. Three public-domain voice packs come installed: men, women, and languages you may not speak. MIC brings in the room instead.

A six-pedal FX rack: gate, band-pass, tape saturation, pitch, echo and reverb, in any order.

Presets A to D hold the whole sound: sources, levels, pedals, sweep rate, squelch and voice packs. Four tuned by ear come installed, so your first sweep is ready.

MACHINE TRANSCRIPTION

Whisper runs entirely on your phone. It reads the untouched signal, before the effects, onto a backlit readout and a word log, labeled ASR INTERPRETATION. It reads the TAPE RECORDER too, marking each word it hears on an all-night tape.

THE INSTRUMENTS

The visualizer puts four readings on one clock: speech, audio, the magnetic field and motion, or pressure, light, temperature and knocks where your phone has the sensors. Its center lights up as each reading rises.

Five field tools, a tap away while the rig keeps running:

EMF meter: the five-light K-II scale ghost hunters know, driven by the phone's magnetometer against the room's normal, with an alarm at the light you choose.
Magnetic pendulum: swings to one of eight words as the field moves, and can say them in a recorded voice. Swap any for your own.
Field lamp: turns on the flashlight when the field jumps past the room's normal.
Music box: a wind-up box that plays only while the field is changing.
SLS camera: draws a stick figure on each shape the pose model reads as a person. Take photos and video, or let it watch and save a clip when something moves or a figure appears.

The TAPE RECORDER records only the room: the oldest ITC method, where a voice turns up only on playback. The QUESTION SESSION marks each question you ask and counts the silence after it.

REVIEW AND EXPORT

Sessions keep each night's recordings, marks, readings, notes and site name together. Loop a phrase, play it from 0.25x to 2x or backwards, see its spectrum, and crop a region into a new capture. Grade each EVP A, B or C. BLIND hides the transcript and notes so a second listener writes down what they hear first.

VIDEO turns a clip into a vertical video to post, with the words as captions.

EXPORT writes one zip: both copies of the audio, transcripts, notes, marks, sensor readings and timestamps, with a Markdown index any computer can open.

THE WATCH

A Wear OS companion remote for THRESHOLD on your phone. While THRESHOLD runs there, pick a tool on the watch's dial, start and stop the sweep, and take photos or video on the SLS camera. It also shows the time, date and battery, in the phone's skin.

PRIVACY

No account, no ads, no analytics, no subscription, no in-app purchases. The speech model and every voice pack ship inside the app, which has no internet permission, so it works in a basement with no signal. Recordings stay on your phone until you share them. GPS tags use the phone's location lookup, which may contact Google.

Recent changes:
1.0.37: In a clip's mark list, every mark keeps its time in the same right-hand column. The clock over the waveform sits on its own plate, so marks near the start no longer run through it. In your first session, BY SESSION now says your clips are under CURRENT SESSION.