Trigger Warning: Music Boxes and Microwave Motion Sensors

Investigators would wind them up and use their stillness as a motion detection indicator. Some devices combine the music box with proximity sensors: if movement is detected nearby, the haunting melody plays. 

Spine-tingling? Yes. 

Reliable? Not always.

Microwave motion detectors evolved from security and industrial applications. Instead of relying on passive infrared (like most motion sensors), they actively emit microwave pulses and measure the reflection to detect movement—even through light materials. When adapted to the paranormal field, devices like the NOVA and Chattergeist's newest 24GHz sensor offered a more data-focused, interference-resistant way to track motion in haunted locations.

Let’s compare what each device is actually doing:

 1. PIR (Passive Infrared) sensors

• Function: PIR sensors detect changes in infrared radiation (heat) within their field of view. All objects with a temperature above absolute zero emit infrared radiation. When a heat source, like a person or animal (or, allegedly, a paranormal entity), moves across the sensor's view, it disrupts the pattern of infrared radiation, triggering an alert.
• Use in Investigations: PIR sensors are placed in locations believed to be active, and if triggered while no investigator or known heat source is present, the activity is attributed to a potential spirit or entity. They can also be used to establish a perimeter around an investigation area to detect intrusions.
• Paranormal Theory: The use of PIR sensors in ghost hunting is based on the theory that spirits can manipulate or radiate energy, potentially causing temperature fluctuations that PIR sensors can detect.  

2. Microwave sensors

• Function: Microwave sensors emit microwave pulses and detect motion based on the reflected signals. When an object moves within the sensor's range, it causes changes in the reflected microwave signal, triggering an alarm.
• Use in Investigations: They are used similarly to PIR sensors to detect movement in areas of suspected paranormal activity.
• Paranormal Theory: Similar to PIR sensors, the use of microwave sensors in paranormal investigations relies on the premise that a spirit's presence or movement could affect the microwave signals, triggering the device.
• ⚠️Note: Microwave sensors can detect motion through most walls and doors. 

3. Ultrasonic motion sensors

• Function: Ultrasonic sensors use ultrasonic waves to detect movement. They emit sound waves at a frequency above the range of human hearing and measure the time it takes for the waves to reflect back after hitting an object. Any change in the reflection patterns indicates movement.
• Use in Investigations: These sensors are positioned to detect movement, especially in areas where it might be difficult to see or monitor manually.
• Paranormal Theory: The theory is that a spirit's presence or movement could interrupt the ultrasonic waves, causing a detectable change in the reflected signals. 

4. Other types of widely used equipment

• Grid lights: These devices project a grid pattern of light, typically on a wall or surface. If a shadow or disturbance interacts with the light grid, it is hoped to indicate a potential paranormal presence or movement.
• Cameras (infrared/night vision): These cameras capture images using infrared radiation and can function well in low-light or dark environments. They are often used to record areas of interest or placed in conjunction with other motion sensors to capture visual evidence of movement or anomalies.
• Vibration sensors: These devices detect minute changes in vibration or tactile sensation. Some models are designed to be sensitive enough to potentially detect a light touch or subtle environmental changes. 

⚠️Important Note: While these tools are commonly used by paranormal investigators, the scientific community largely considers the claims of their effectiveness in detecting ghosts as lacking scientific evidence. The interpretation of data from these devices often relies on personal beliefs and anecdotal experiences rather than verifiable scientific principles.  

What you need:

• A trigger music box motion sensor
• A microwave motion detector like Lauren Haunts' NOVA or Dimension Devices 24GHz Sensor addition for your Chattergeist device
• A narrow hallway or enclosed space
• Notebook and stopwatch

Steps:

1. Set both devices side-by-side, facing the same zone.
2. Start a controlled session: announce you’re beginning, ask a question, and stay silent.
3. Document any activations with time stamps.
4. Next, try blind movement from out of view (behind a curtain, around a corner).
5. See which device reacts—if either.

Goal: Compare sensitivity, reliability, and range. You’ll quickly see that the NOVA picks up more subtle, “non-obvious” motion patterns—especially when IR or temp shifts wouldn’t trigger other tools.

We moved to using the NOVA for its:

• Microwave-based detection: Less prone to false positives from temperature shifts
• Configurable sensitivity: Can be adjusted to environment size and layout
• Interference protection: Unlike PIR, microwave signals aren’t fooled by light beams or open windows
• Better storytelling: Correlates well with movement on video, EVPs, or EMF spikes

Music boxes? They’re a spooky mood, sure but too many false alarms for serious documentation.

PIR sensor based gear:

•  False alarms: They are susceptible to false alarms caused by moving heat sources, such as insects, heating systems, cooling systems, or drafts.
• Limited range and field of view: PIR sensors have a limited range and a specific field of view, so they may miss activity outside that range. They may also struggle to detect finer movements, particularly at a distance.
• Difficulty with temperature fluctuations: Their effectiveness can be affected by ambient temperature, as they rely on detecting temperature differences. In hot environments, the contrast in infrared radiation may not be significant enough to trigger the sensor.
• Inability to differentiate sources: They cannot distinguish between different heat sources, such as a human, an animal, or an inanimate object that emits heat.  

Microwave Sensor based gear:

• False alarms: Because of their sensitivity and ability to detect motion through solid objects, microwave sensors can be prone to false alarms caused by movement outside the area of interest or by vibrations in nearby structures or objects, like pipes or shifting furniture.
• Interference with other equipment: The emitted microwave signals can potentially interfere with other sensitive electronic equipment used during investigations.
• Higher power consumption: Compared to PIR sensors, microwave sensors may require a continuous power draw and can be more energy intensive.
• Limited discrimination capability: Similar to PIRs, microwave sensors are designed to detect movement and may not be able to identify the specific object or source of the detected motion. 

In general:

• Avoid placing either tool near radiators, vents, or reflective surfaces
• Always do pre-investigation tests to understand field range and blind spots

• Test both tools during setup to mark their limits
• Only rely on them if activations correlate with other data points (video, audio, environmental shift)
• If using during public investigations, clearly explain how each works to avoid dramatizing ordinary triggers

• Hellkson, L. (2023). NOVA Technical Specs and Usage Guide. Lauren Haunts Private Archive.
• Lauren Haunts – Tools and Tutorials for Microwave Motion Detection – [https://www.laurenhaunts.com]
• National Research Council. (1997). Radar and Microwave Remote Sensing Fundamentals.
• Graves, C. (2018). Paranormal Tech: Tools for the Modern Investigator.
• GhostStop.com – Motion Sensing Tools Overview: [https://www.ghoststop.com/motion-detectors/]