Android version of Pocket Ghost paranormal detector. Subsonic (infrasound), supersonic and audible IIR filters calculate the ParaNormal Quotient(PNQ) at your location. The magnetic field is also displayed.
An essential tool for the aspiring or professional ghost hunter!
Theory of Operation (Only for nerds) ...
It has been reported that paranormal activity is evidenced by sounds inaudible, or barely audible, to the human ear. Animals, whose hearing is more acute at higher frequencies than ours, are able to detect supersonic sounds, generally above 12-15 kiloHertz or so. For example, dogs are reported to behave oddly during supernatural events. Sounds of very low frequency, less than a hundred Hertz or so, are normally felt rather than heard by humans. The built-in microphone circuitry in most handheld devices is designed to detect frequencies in the audio range, but there is some residual response from the circuitry at the very low (subsonic) and very high (supersonic) frequencies.
Ghostroid uses fast software-based Infinite Impulse Response (IIR) filters to measure the level of sub- and super-sonic sound pressure waves arriving at the microphone. It also measures the audible sound level. The three ranges are shown on the Ghostroid display via three meters, which move dynamically and are updated several times a second. The Para Normal Quotient (PNQ) is calculated from a formula that sums the sound levels in the sub- and super- sonic ranges, and subtracts the audible range value. This yields a number which increases as the sub- and super- frequencies (which are difficult or impossible for us to hear) increase, as compared to the audible frequencies.
The PNQ value is shown by a set of concentric bands at the centre of the display. High PNQ values may be caused by a variety of events: Low frequency rumbling (e.g. from heavy trucks or machinery), High frequency noises (e.g. dog whistles, or keys jangling) as well as Supernatural phenomena (please don't drop your Android when you run away in fright!)