A tactile transducer or "bass shaker" is a device which is made on the principle that low bass frequencies can be felt as well as heard. They can be compared with a common loudspeaker, just that the diaphragm is missing. Instead, another object is used as a diaphragm. A shaker transmits low-frequency vibrations into various surfaces so that they can be felt by people. This is called tactile sound. Tactile transducers may augment or in some cases substitute for a subwoofer. One benefit of tactile transducers is they produce little or no noise, if properly installed, as compared with a subwoofer speaker enclosure. Applications A bass-shaker is meant to be firmly attached to some surface such as a seat, couch or floor. The shaker houses a small weight which is driven by a voice coil similar to those found in dynamic loudspeakers. The voice-coil is driven by a low-frequency audio signal from an amplifier; common shakers typically handle 25 to 50 watts of amplifier power. The voice coil exerts force on both the weight and the body of the shaker, with the latter forces being transmitted into the mounting surface. Tactile transducers may be used in a home theater, a video gaming chair or controller, a commercial movie theater, or for special effects in an arcade game, amusement park ride or other application. Related to bass shakers are a newer type of transducer referred to as linear actuators. These piston-like electromagnetic devices transmit motion in a direct fashion by lifting home theater seating in the vertical plane rather than transferring vibrations (by mounting within a seat, platform or floor). This technology is said to transmit a high-fidelity sound-motion augmentation, whereas "Shakers" may require heavy equalization and/or multiple units to approach a realistic effect. Virtual reality There are other products which employ hydraulic (long-throw) linear actuators and outboard motion processors for home applications as popularized in "virtual reality" rides. These products differ radically from tactile transducers in that they require the manual composition and synchronized playback of motion signals, in addition to the standard soundtrack that the motion is meant to accompany. Designs Various designs for tactile transducers have been presented since the 1960s, most of which fall under the "shaker" category. Shakers create a vigorous vibration by moving a mass (usually a magnet) which is bolted to a final mass (like a chair or couch). A simple example of this