Some science behind the scenes
A transducer is a device that converts one type of energy to another. Energy types include (but are not limited to) electrical, mechanical, electromagnetic (including light), chemical, acoustic or thermal energy.
Many types of natural energy cannot give you a spiritual experience directly – heat cannot, light cannot, but when converted to mechanical energy including sound or electrical signals it can, thus the transducers that help to provide a spiritual experience convert energy that would normally have no effect spiritually into energy that does.
Thus a spiritual transducer is any device capable of converting electrical, mechanical, magnetic, electromagnetic (including light), chemical, acoustic or thermal energy into one of the forms of spiritually usable energies.
There are various types of transduction
Piezoelectricity - mechanical to electrical transduction [and vice versa] Piezoelectricity is the charge which accumulates in certain solid materials (notably crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress
Magnetic Induction - changes in an electric current or magnetic field can cause ("induce") changes in the other, according to Maxwell's equations and more particularly Faraday’s law. Faraday's law describes how a time varying magnetic field creates ("induces") an electric field. This aspect of induction is the operating principle behind many electric generators: for example a rotating bar magnet creates a changing magnetic field, which in turn generates an electric field in a nearby wire.
A changing [pulsed] magnetic field will induce an electric field in anything that will conduct it.
Geomagnetism - there are two possible ways in which a fluctuating geomagnetic field can induce an electric current:
The magnetic field itself may induce an electric current in us. So in some senses the electrical systems of the brain [or of the body for that matter] are being stimulated by remote magnetic fields to produce a sort of ‘false signal’ along the nerve cell of varying frequency depending on the radiation.
Or by standing in the focal point of an electric current from a Telluric current we may then receive the equivalent of a very mild electric shock, so direct electrical stimulation
Pyroelectricity - is the ability of certain materials to generate a temporary voltage when they are heated or cooled. Light and electromagnetic waves of any frequency will heat surfaces that absorb them. Electromagnetic energy in the form of light and infrared radiation can thus heat the crystals in bones and tendons, for example, to produce electrical energy.
Thermoelectricity - The thermoelectric effect is the direct conversion of temperature differences to electric voltage[and vice-versa]. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. Although the effect was first noticed in metals, any crystalline structure will demonstrate the effect
It is via transducers that stimulation usually works if indirect mechanisms of stimulation are used.