Analog Sound Detection Unit
Wondrous Item, common (requires attunement)
This off-white, boxy 90’s sound sensor has a small perforated speaker grille, a chunky sensitivity knob, and a row of colored LEDs that climb from green to red. The casing is scratched and slightly yellowed with age. A coiled cord trails from the back, even though it somehow still works without being plugged in.
When placed in a quiet area, the device emits a faint electronic hiss—like it’s straining to hear something just out of reach.
Sometimes the red light blinks… even in total silence.
Properties
Ambient Listening
As an action, you may place the sensor on a surface within reach.
It monitors a 30-foot radius for unusual noise.
If a creature or spirit makes sound within the area:
The LEDs spike upward.
You learn the direction the sound originated from.
This can detect:
Footsteps
Breathing
Scratching
Distant whispers
Even if the source is invisible or incorporeal.
Sound Pattern Read
Once per short rest, when the device triggers, you may focus on it for 1 round.
You learn whether the detected sound was:
Physical movement
Environmental noise
Or supernatural in origin
Early Warning
While you are within 60 feet of the active sensor:
You gain advantage on Wisdom (Perception) checks relying on hearing.
You cannot be surprised by undead or spirits that make noise within its range.
Old Tech Limitations
Loud environments cause false spikes
Requires a flat surface to function properly
Does not detect completely silent entities
Malfunction Quirks
Roll or choose:
The LEDs pulse like a heartbeat.
It occasionally plays a faint pop like a cassette stopping.
The sensitivity knob turns on its own.
It sometimes reacts to someone whispering a name.
Notes: Advantage: Perception, As an action, you may place the sensor on a surface within reach. It monitors a 30-foot radius for unusual noise. If a creature or spirit makes sound within the area: The LEDs spike upward. You learn the direction the sound originated from. This can detect: Footsteps Breathing Scratching Distant whispers Even if the source is invisible or incorporeal. Early Warning While you are within 60 feet of the active sensor: You gain advantage on Wisdom (Perception) checks relying on hearing. You cannot be surprised by undead or spirits that make noise within its range. Old Tech Limitations Loud environments cause false spikes Requires a flat surface to function properly Does not detect completely silent entities Malfunction Quirks Roll or choose: The LEDs pulse like a heartbeat. It occasionally plays a faint pop like a cassette stopping. The sensitivity knob turns on its own. It sometimes reacts to someone whispering a name. , Requires Batteries
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