Star Trek: How Do Sonic Showers Really Work?
Whether their day is filled with planetary surveys or Borg drone dodging, every Starfleet officer needs a place to wash away the sweat, stress, and occasional blood wine spill. For officers living their lives aboard Enterprise or another Federation starship from at least the 23rd century going forward, one of the most efficient ways to accomplish this is with the ever-convenient sonic shower.
In the world of "Star Trek," a sonic shower is a water-saving bathroom appliance that uses sonic waves to strip away everything from sweat and debris to hot cocoa carelessly spilled by a socially awkward ensign. They first show up in "Star Trek: The Motion Picture" (the movie William Shatner says finally showed the series' true potential) when the Ilia probe, V'ger's duplicate of the recently deceased Deltan Lieutenant Ilia (Persis Khambatta), appears in one located in the starship's crew quarters. Although brief, the scene reveals that some sonic showers seem to be equipped with a translucent door that offers some degree of privacy. It's also implied that Robo-Ilia's shower includes either replicator or transporter technology, as clothing appears on her before the Ilia probe exits the shower.
Although it's not clear exactly how the sonic shower works, one scene from the "Star Trek: Voyager" episode "Juggernaut" suggests the machine's sonic pulses may loosen unwanted particulates, causing them to fall away from the body for the replicator system to recycle them. The episode ends with B'Elanna Torres (Roxann Dawson) stepping into her sonic shower after a difficult mission. Inside the shower stall, she momentarily leans against a lit wall before using a voice command to activate the shower, causing the grime and debris to seemingly lift away from her body in particles.
Sonic showers have adjustable frequencies
Just as we can change the temperature and water pressure in our showers, the sonic showers in "Star Trek" can also be adjusted by frequency, a function Enterprise doc Joseph M'Benga (Babs Olusanmokun) demonstrates in the "Star Trek: Strange New Worlds" episode "Under the Cloak of War." Mirroring B'Elanna's post-trauma shower in "Juggernaut," M'Benga steps into his own sonic shower after killing Dak'Rah in the sick bay, directing the computer, "Set sonic shower to four." Similar to the variable temperatures of a hot or cold shower, this suggests that certain frequencies create a more intense experience.
This feature gets pushed to its limit in the "Star Trek: Lower Decks" episode "Kayshon, His Eyes Open." Unlike the ship's higher-ranking officers, the lower deckers on the Cerritos, who sleep in bunks rather than private quarters, use unisex communal sonic showers conveniently located near their barracks-style corridors housing the ensigns, Starfleet's lowest-ranking junior officers. Like M'Benga's and Torres' showers, the large communal shower features pulsing light walls along with translucent, waist-high dividers that seem to function more as something for hanging towels on than to provide privacy. As self-assigned "unofficial leader" of Beta shift, Ensign Mariner (Tawny Newsome) attempts to exert her authority over the newly-assigned Jet, the two ensigns take turns competitively cranking up the sonic frequency via their shared LCARS panel. The buzzing intensifies, causing the other panicked ensigns to grab their ears and flee before Mariner and Jet's noses begin to bleed from the sonic pulses.
Exactly how dangerous these pulses could potentially be is shown in the "Voyager" episode "Live Fast and Prosper," when Janeway's sonic shower frequency malfunctions, creating a high pitch that causes her mirror to shatter.