Songs in the Key of Lock

If you're tone-deaf, you're out of luck.

"Rhythm is the key
as you open up the door"

— Hive, Ultrasonic Sound

Using music and musical instruments as security measures. Pianos or similar instruments are common, as you are dealing with keys. Can often be the way to conceal your secret lair by being Hidden in Plain Sight. The tune itself may be significant/ironic, or the Theme Tune or Leitmotif of a character.

Subtrope of Solve the Soup Cans. Compare with Musical Trigger. Can be related to Only Smart People May Pass, if actual musical ability is required. Sister Trope to Open Sesame, when the password is a spoken phrase.

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Examples

Anime & Manga

• In My-Otome, a specific song, from which each of the three main characters knows one verse each, is one of the three requirements for activating the Harmonium.

Comic Books

• In the 60s Archie story "That Way Out Sound", Mr. Lodge shows off a vault with a door that can only be opened by the "unearthly, weird, way-out sound" produced by a one-of-a-kind tuning fork. Unfortunately, Archie accidentally locks him inside the vault, tuning fork included. A variant ensues as Archie and his friends free him by reproducing the "way-out sound" with their rock band instruments; it turns out there's no sound the Archies don't hit sooner or later.
• Disney Ducks Comic Universe:
  • In a Scrooge McDuck story by Carl Barks that's a riff on The Hunchback of Notre Dame, Scrooge programs his vault so that it can only be opened by playing "My Bonnie Lies over the Ocean". Trying to protect his secret by using a wishing well (It Makes Sense in Context), he inadvertently reveals it to the hunchback (who lives near the bottom of the well scooping up the coins people throw in and eavesdropping on their wishes in the process), which kicks off the plot.
  • A DuckTales (1987) comic written for Disney Adventures had a similar plot, in which Scrooge has a voice-activated lock to the vault on his money bin which only opens when it hears him singing the opening lines of "Comin' Through the Rye". And the Beagle Boys just so happen to have a cousin, Baritone Beagle, who's good at impressions...
• One shows up in Warren Ellis' Ignition City, triggered by the owner's favorite song - "A Nightingale Sang In Berkeley Square".
• In one issue of The Incredible Hulk the Leader's time machine is programmed by playing a piano keyboard.
• In one issue of the Muppet Babies comic ^note Based on Muppet Babies (1984), the group imagines that the world is running out of music. In their imaginations, it turns out that it's being eaten by the Note-All, with approval from Piggy, who wants her music to be all there is. His staff puts the rest behind bars. When the Note-All eats Piggy's singing, as well, she decides to go free her friends. When physical keys don't unlock the bars, Rowlf suggests a musical key. When Piggy hits high C, the bars open.

Film — Animated

• Despicable Me 2: The entrance to El Macho's lair is protected by the tune of "La Cucaracha." Hilarity Ensues as Gru tries to play the tune and his nacho sombrero hinders him every step of the way.
• Monsters vs. Aliens: The security lock to the central core of Galaxar's ship is protected by a musical sequence which seems to be right out of DanceDanceRevolution.

Films — Live-Action

• In Batman Begins, the Batcave is accessed from Wayne Manor by playing a specific sequence of keys on the piano. This is carried over to The Dark Knight Rises. It does not, however, happen in The Dark Knight; a different "Batcave" is in use in that film, due to Wayne Manor being under reconstruction.
• In The Goonies, a creepy pirate organ opens a door or collapses the floor depending on whether you play the right tune or not.
• In Hudson Hawk, the villains use a ridiculous-looking set of handcuffs with colour- and sound-coded buttons. Which makes it trivial for Hawk to get out of them (in fairness, it's probable that they intended him to escape eventually).
• James Bond
  • In For Your Eyes Only, the Identigraph room in Q's lab has a musical lock. The 7-note key is the title passage of "Nobody Does It Better" from The Spy Who Loved Me (2 films earlier); it is less obvious, though, because Q stops after 5 notes and James Bond fills in the final 2 a few seconds later.
  • In Moonraker, access to Drax's base is controlled by a musically coded keypad. The tune is the same five notes used to communicate with the aliens at the end of Close Encounters of the Third Kind.
• In Paddington 2, Madame Kozlova's fortune is hidden in a secret compartment inside a fairground organ which unlocks when a specific series of notes is played.
• In Prometheus, the Engineers' ship is activated by pressing buttons in order and by playing notes on a flute-like instrument.
• The film adaptation of Richie Rich had this with the parents unlocking the family vault by singing along with the code tune, "Side by Side", as a duet. The villain was not amused.
  • The lock stops recording after the first line, "Oh, we ain't got a barrel of money," which means that this is the actual key (as ironically befits a massive vault that contains valuable mementos, not real valuables). The parents only sing the rest of the verse out of nostalgia and a need to be saccharine.
• The movie WarGames has the main character locked in a holding cell. He gets out by recording the musical tones from the keypad to his cell and playing them back from a microcassette recorder.
• In What a Carve Up!, Ernie accidentally activates the secret door in the music room by pulling out the stops on the organ while Syd is searching the walls.
• Willy Wonka & the Chocolate Factory. In Willy Wonka's factory, the door to enter the Chocolate Room (with the chocolate river) had a musical lock. The tune for the lock is the Overture from "The Marriage of Figaro," by Mozart, not Rachmaninoff, as Mrs. Teavee claims.
• In Yellow Hair and the Fortress of Gold, Man-Who-Knows tells the Pecos that the horn is the key to gaining access to the Tulpani's secret cave system. Arriving at the seemingly dead end box canyon, Pecos blows through the horn and the reverberations cause a secret entrance to open.

Literature

• In book two of The 39 Clues, the search for the Clue eventually leads Amy and Dan to the house of a man named Fidelio Racco; specifically, a keyboard in his house that Mozart played. Playing a certain song (a unique version of Mozart's "KV 617" left in the Parisian Catacombs centuries ago) on this keyboard causes a trapdoor in the floor to open, revealing two swords made of a tungsten alloy, tungsten being the Clue. The trigger even works when a booby-trapped key causes the instrument to explode before the song can be finished.
• John Galt likes using a sound lock to protect things he doesn't want outsiders to see in Atlas Shrugged, although it's not sung. Backed up with Self-Destructing Security for anyone who tries to force their way in.
• In Killashandra, part of Anne McCaffrey's Crystal Singer series, the lock hiding the illegal computer equipment inside the organ is opened by playing a (supposedly) original melody. Fortunately, the protagonist knows Beethoven's fifth symphony, and can play the opening line "accidentally" while tuning it.
• As captured James Bond in Devil May Care is sent for a mission to Afghanistan on the behalf of the Big Bad, he and Chagrin come across a vault door which requires a code to be opened. Each press for a five-digit code that opens it emits a sound of its own, and Bond memorizes it to teach it to his fellow prisoner Scarlett.
• In The Mouse Watch, Dr. Thornpaw captures and imprisons several of the titular heroes. Bernie and her teammates figure out that Thornpaw is using a musical lock, and then Bernie realizes that the solution is to sing "Three Blind Mice".
• Old Kingdom: A shortcut to Abhorsen's House in Sabriel will only open to the sound of Mosrael, a bell which is otherwise never used in the series except when all the bells are rung together (it sends the ringer into Death).
• Pops up everywhere in Sharon Shinn's Samaria series. All angels are born with perfect pitch and singing voices, with which they can pray for all manner of divine intervention - rain or sunshine, cures for plagues, or even a good old-fashioned smiting. Meanwhile, enterprising mortals have come up with musical locking boxes and other such aural toys. The theme of musical control is so heavily emphasized that the nature of the Samarians' god winds up being something of an Un Reveal.

Live-Action TV

• An episode of Chuck involved a hidden compartment opened with a high C note. Casey uses his choir-boy background to produce the note.
• CSI: In "Suckers", they investigated the robbery of a hotel vault. At the end Grissom realises that the lock was programmed so the tones of the numerical keys would tap out the melody for "Three Little Maids From School" from The Mikado. A tune that would be familiar to the thieves; the manager was co-operating with them to carry out an insurance scam.
• Doctor Who: In "The Five Doctors", the Fifth Doctor played a harp to get into the villain's lair. The tune itself was Hidden in Plain Sight.
• In one episode of Kyle XY Kyle and Jessie called Kyle's girlfriend to get her to play a song that opened a lock.
• This was done in the season 3 finale of Lost: Charlie had to enter a code to the tune of a Beach Boys song to unjam the signal going out from the island.
  • Good Vibrations, to be specific.
• There's an episode of MacGyver ("The Heist") featuring an ultra-high-tech (for the time) lock which requires four tones emitted by a remote control. This being MacGyver, he improvises by playing some wineglasses.
• The first season of The Mole ended with a complex, multi-part puzzle that involved one of the remaining contestants stuck in a locked room with a xylophone and sheet music. The door would only open if he could play "Mary Had a Little Lamb"... and he couldn't read music.
• Murder, She Wrote: In "A Murderous Muse", the killers set up a system whereby when the Victim of the Week plays a certain chord on the piano, it unlocks the secretary behind him and fires the gun hidden within.
• Psych: One of Gus's Blackappella bandmates sent the group an encrypted e-mail just before he was murdered that could only be opened if all of them sang "It's So Hard to Say Goodbye to Yesterday". Once Shawn stepped in as the harmony, they unlocked a video revealing who set the victim up to be killed.
• In Stargate Atlantis, Janis, an Ancient scientist, used three different tones played in order to hide his secret lab.
• Star Trek: The Original Series: in "The Paradise Syndrome" the obelisk left by the Preservers had a door that opened in response to a specific sequence of sounds (musical notes or speech tones). ^note  In this case it matched the sound of a communicator opening.
• Star Trek: Picard: In a callback to "Encounter At Farpoint", Moriarty is deactivated by whistling "Pop Goes The Weasel".
• Titans (2018). Near the end of season one, Dick Grayson goes into an extended dream sequence about returning to Wayne Manor. He accesses the Bat Cave from one room by playing a sequence on the piano; possibly a Shout-Out to the Batman Begins and The Dark Knight Rises examples in the Live Action Film section.
• In the White Collar episode "Empire City", the safe in the Cotton Club opens for a few bars of the jazz classic "Harlem on my Mind" as sung by the proprietor. Neal sneaks a vinyl recording of this music past the metal detector in order to open the safe.
• Wonder Woman. In the 1st season two-part episode "Judgment From Outer Space", Wonder Woman meets a space alien named Andros. During Part 1 she hears him whistle a six note musical phrase, and in Part 2 she uses that same phrase to both open the outer hatch on his space ship and deactivate a force field inside the ship.

Radio

• One Adventures in Odyssey episode had the characters facing an organ with the clue to "Start in the center and play 'a deaf cabbage.' Robin has had music lessons, so she realizes that the phrase can be played on the organ and does so, opening a hidden door.

Tabletop Games

• Dungeons & Dragons
  • 2nd Edition AD&D adventure OA6 Ronin Challenge. The Su-Rai Vault has a dangerous gas trap. One of the doors in the vault is covered with the notes of a simple tune. If a Player Character with the Singing or Music proficiency sings the tune or plays it on a musical instrument, the valve that releases the gas trap will stay sealed for 24 hours, allowing the party to explore the vault without being gassed.
  • 2nd Edition AD&D supplement The Ruins of Undermountain II: The Deep Levels. The Undermountain dungeon has a number of Cool Gates that allow access to it. In the Campaign Guide booklet, the table of Random Gate Effects includes a gate that is activated by the playing of a specific musical tune.
  • The 3rd Edition Dungeon Master's Guide mentioned a note played upon a lute as a possible key to open a magical door.
  • Dungeon magazine
    • Issue #49 adventure "Castle of the Blind Sun" has several magical doors which will open only if the notes B, G and C are played in that order on a musical instrument.
    • Issue #63 adventure "Hunt for a Hierophant". The door that leads to the place where the Hierophant druid Leander lies sleeping can only be opened by a specific set of musical notes played on a silver Harp of Charming.
  • In Planescape, gates to other planes can be opened this way.

Video Games

• The 7th Guest has one shown here involving a piano. Technically, though, it's more of a Simon Says puzzle in this case.
• Alida The Enigmatic Giant: Vaults scattered around the island are fitted with sensitive microphones which pick up the sound from the island's massive, fully functional electric guitar. Each and every component of the guitar must be set correctly - and that includes the peghead, switch, and potentiometer dials, before the guitar's sound can open the doors, provided a designated door has been primed to receive the sound, that is. The same game also has a small keyboard of tubular bells that unlocks the tram to the Switch.
• One early area of Another Code has you play the piano to open a secret passage, and later using a music box to open a fireplace passage.
• Most of the time in Aquaria, Naija uses her songs to change into a form that is best suited for passing a certain obstacle, i.e. using the Beast Form to swim past strong currents. However, there are a couple of cases where just singing is enough to remove an obstacle, such as the door in the Song Cave, the whale in The Abyss, and Li's cage near the end of the game.
• In the text adventure Augmented Fourth, the player character has occasion to play a piece called "The Well-Tampered Xylophone", which consists of exercises in "twenty-five keys". The extra one turns into an actual key.
• In Baldur's Gate: Dark Alliance II, you have to open a secret passage by playing a harpsichord.
• Brütal Legend has various Guitar riff sequenced that activate certain powers, up to and including opening new areas.
• In Chrono Cross, each element has a unique tone when cast in battle. Playing the Song of Life with these tones when fighting the Final Boss will instantly win the battle and free Schala from Lavos. This unlocks a better ending than the player would get by killing the boss. Being able to pull it off successfully is hard because the boss can interrupt (or help) the melody with his own magic.
• You don't actually have to solve a puzzle, but in Chrono Trigger playing an organ always reveals hidden doors.
• Getting through one Bonus Dungeon in Cosmic Star Heroine requires playing a sequence of notes on a piano. In practice this is a simple Lock and Key Puzzle as you don't personally choose any notes, you simply need to find a piece of paper and then get to the piano.
• Dream Chronicles series loves "repeat the sequence" puzzles involving pressing the keys of some musical instrument (even if it's just the key order you have to memorize, not the tune itself - you can see which keys are being activated).
  • The original game has the piano room, where clicking portraits on the wall will produce different tunes for you to repeat; completing them all opens the door to the outside.
  • The second game has the organ room, where you need to repeat several tunes in order to unlock the passage to the second floor. Another floor has a puzzle requiring you to put several musical instruments in proper order, indicated by a book found in the library.
  • The third game has another organ-like instrument, where the same sequence-repeating type of puzzle protects several items you need to obtain.
• In the Bloodmoon expansion for The Elder Scrolls III: Morrowind, the Ritual of Earth requires you to listen to a set of geysers from some stalactites and then activate the stalactites in the same order.
• Eternal Darkness: Sanity's Requiem has you play one song three times: twice on an organ, once on a piano.
• Eternal Sonata has you play increasingly long portions of Chopin's "Nocturne" on a large piano in order to progress through the Xylophone Tower of the Shining Keys. It doesn't unlock door or gate, but it does cause a sloped ramp to appear each time.
• Fallout 3's quest Tranquility Lane, set in a Lotus-Eater Machine, has a possible ending where the player character can activate the simulation's failsafe by reproducing the ubiquitous Leitmotif on a collection of tuned household items.
• In Fallout: New Vegas: Dead Money, you have to play Vera's song holotape to unlock the vault elevator (or have Christine say the password with her new voice), after retrieving the music tracks from the receptionist terminal.
• In Final Fantasy II, the entrance to Kashuan Keep can only be opened by the voice of a member of Kashuan's royal family or the ringing of the Goddess's Bell.
  • Final Fantasy VII has the final Limit Break for Tifa that is obtained by playing the right notes on the piano.
  • Final Fantasy VIII has an organ that needs to be played to open a gate.
  • A dungeon in Final Fantasy IX has bells as Interchangeable Antimatter Keys.
  • Final Fantasy X-2 has a puzzle involving repeating notes.
• Goat Simulator 3: The locked mausoleum can be opened by playing "The Imperial March" on the bell tower's bells.
• Near the end of God of War III, there's a puzzle that doesn't even bother trying to hide what it is, as the "notes" are copies of the PlayStation's four main buttons and the tune you play is the franchise's leitmotif.
• Illusion of Gaia requires protagonist Will to play specific tunes on his flute to open several gates.
• The main objective in Impossible Mission II is to collect six pieces of a song (two of the eight pieces are duplicates) that unlocks the express elevator to the penthouse control room.
• The Journeyman Project 3 has a set of Buddhist Prayer Wheels on which the player must playt a prayer chant. One of them is squeaky and must be oiled first.
• King's Quest IV: The Perils of Rosella features an organ at the top of a tower in a haunted house. The organ has a secret drawer in it, which opens if the organ is played correctly (Rosella has to find the sheet music first).
• King's Quest VII: The Princeless Bride has another music puzzle in Etheria involving a harp, which will transport Valanice to a sort of pocket dimension where she can speak with the Three Fates if she plays the right notes on it. The clues to the notes are given by the faerie dragons flitting around in another area of Etheria.
• The FMV Lawnmower Man game has a very basic Simon-like musical keyboard level, but it takes forever to watch the player character enter the code after you do.
• The Legend of Zelda:
  • The Legend of Zelda: Ocarina of Time: Just as when its predecessors in the franchise often removed something barring your progress (except in A Link to the Past), Link's ocarina can be used for the same purpose. Zelda's Lullaby will trigger mechanisms if Link stands on "the Crest of the Royal Family" a.k.a. the Triforce; the Song Of Time removes and summons blocks with the Door Of Time's design on it, starting with the Door Of Time itself; and the Song Of Storms opens up the Bottom Of The Well.
  • The Legend of Zelda: Majora's Mask: Each of the four temples in Termina requires playing a specific song to open its entrance (or, in one case, simply reach it): "Sonata of Awakening" for Woodfall Temple, "Goron Lullaby" for Snowhead Temple, "New Wave Bossa Nova" for Great Bay Temple, and "Elegy of Emptiness" for Stone Tower Temple. This contrasts the temple songs from Ocarina of Time, which simply warped you to the temples' whereabouts.
  • The Legend of Zelda: The Wind Waker: The two temples whose sages empower the Master Sword require Link using the eponymous baton to conduct sacred melodies onto the newly-elected sages so they can open the temples' entrances, as well as inner parts afterward: "Earth God's Lyric" for Earth Temple and "Wind God's Aria" for Wind Temple. Notably, these two songs also make up for the game's title screen theme as well as the credits music.
  • The Legend of Zelda: Spirit Tracks: The Spirit Flute, which utilizes the DS microphone, has magical properties enabled with the songs learned. Playing duets with the Lokomos help restore the Spirit Tracks, which enable you to go to new areas.
  • The Legend of Zelda: Skyward Sword: The "Ballad of the Goddess", when played with the Goddess Harp, activates and opens the Gate of Time in Faron Province. The following three melodies open the entrance spot to the Silent Realm areas for the mainlands of the surface, tailored for the chosen hero. The last melody ("Song of the Hero") grants access to the Silent Realm area of Skyloft and also holds the key to unlock the final dungeon in the game.
  • The Legend of Zelda: Breath of the Wild: Compared to previous games, the game has a reduced presence of this trope. One of the Ancient Shrines, located in an area close to Rito Village in Tabantha, requires a quintet of Rito girls to sing in a specific order (and be assisted by Link waving a Korok Leaf to bring wind onto holey stones) in order to erect it.
• Loom's Magic Music starts you off with the "Opening" draft, which works as a universal one of these (where The Password Is Always E-C-E-D).
• In The Lost Crown, Nigel must repair a church organ and then play a specific sequence of notes to banish an evil ghost which blocks his path to a vital clue.
• There are a couple of puzzles in Lufia II: Rise of the Sinistrals where you have to step on "musical note" tiles in a certain order to open the locked doors.
• Luigi's Mansion 3: One of the collectible gems is unlocked by using the air from Luigi's Poltergust to play the franchise's main melody on a group of bottles.
• Lunar: The Silver Star has a duet between true lovers as the key to one dungeon. A long-distance duet between the leads opens it. Kyle and Jessica make for a Dreadful Musician duo, while Nash is too worried about stepping on Mia's notes to harmonize.
• Myst:
  • The Selenitic Age Descriptive Book is accessed via a five-note combination. Then to enter The Maze, you have to play the five ambient sounds in the proper order. Furthermore, the sounds in the maze indicate the compass direction you need to go.
  • All the Myst games seem to have at least one sound puzzle each. In Riven, the combination to unlock Catherine's cell is revealed by listening to Gehn's watch.
  • Riven also has the overarching animal-sounds puzzle that is scattered across the islands. There are five balls with a D'ni number carved in them, and each makes a Riven animal sound when spun (using at least one fictional animal.) The code makes perfect sense, as it would only be understandable by someone well-versed in both Riven and D'ni culture (it was intended for Atrus, but the player will figure it out eventually.)
  • Myst IV: Revelation involves using Sirrus' Spider Throne to vibrate four different pieces of minerals, so that all of them being pushed out of their literal "locks" deploys a bridge to a bomb factory. The musical element comes from the tones Spire's crystals give off when their electrical charge fades, which the Throne channels via huge cables within the Age.
• Nancy Drew MANY. After thirty three games, the series has an orchestra's worth of musical locks, including;
  • Piano keys (Message in a Haunted Mansion, Secret of Shadow Ranch, Blue Moon Canyon, Warnings at Waverly, Silent Spy)
  • Harmonica (Haunted Carousel)
  • Glockenspiel (Captive curse)
  • Music box (Sea of Darkness)
  • Bagpipes (Silent Spy)
  • Banjo embedded in a well (Crystal Skull)
  • Zeusaphone (Deadly Device)
  • Musical ventriloquy dummy (Crystal Skull)
  • An entire set of stairs (Blackmoor Manor)
• The drawbridge passtune in NetHack. You find it out by either playing Mastermind or by having your god tell it to you.
• At one point in The Neverhood, you have to open a door by spitting into a series of tubes to make them whistle the same tune as another series of tubes.
• Nine Hours, Nine Persons, Nine Doors: Unlocking the exit door to the First Class Cabin requires playing a piano. After collecting the sheet music, it's revealed that the piano is tuned incorrectly, so the actual puzzle is matching the proper notes to their altered locations. It's actually one of the easiest puzzles in the game, as the set of keys you're able to choose from is quite small, and after playing the first line correctly, the game completes the rest of the song for you. Notable in that the piece of music played isn't a character theme, scare chord, or in any way related to the game's soundtrack, but the Westminster Chimes. This prompts a comment from one of your companions as to Zero's motives and nothing else.
• In Outcast you had to put the right pipes (as in flute pipe) into the right sockets on an altar (or something) to play a certain melody. After accomplishing this, you'd get another key for something else...
• Phantasy Star II: In order to get the card keys to open the Dams, you need to play a keyboard, however you must learn the Musik skill to even be able to play the keyboard. At one point, you trade away one of the songs you no longer need.
• Prince of Persia: The Sands of Time. In the GBA version, there are several levels that are passed by playing a certain tune in a certain sequence.
• Resident Evil has a piano you play Beethoven's "Moonlight Sonata" on to unlock something. Jill knows piano; Chris has to find Rebecca.
• One way of getting control of the Nautilus in the game Return to Mysterious Island involved playing a few bars of music solely on the black keys of the Nautilus's organ (as, apparently, Captain Nemo specialized in playing music that required only the black keys).
• Sacred Earth - Promise: The harpies in Fimbulvetir Forest set up doors that can only be opened by musical plants to play a specific sequence of notes. The forest also contains an underground ruin where the player has to go through the exits of a looping room in a specific order based on the notes that are made upon passing through.
• Safecracker has a fairly easy puzzle in the Crabb & Sons mansion/office's music room, used to unlock a well-hidden safe inside a piano. The code is the first 14 notes of Twinkle Twinkle Little Star.
• Schizm: Mysterious Journey runs in a similar vein as the above, with a set of Argilan prayer grinders. After an alien priest shows up and speaks a string of words that open a hidden door, you have to play it back using these devices.
• Seiklus uses a giant piano. The keys are colored, and you have to jump on them in a sequence found elsewhere.
• Such a puzzle exists in Silent Hill, the only clue being a poem about birds (and interestingly, the correct solution produces no music because the keys you have to press are all broken). A puzzle involving a child's toy piano with pictures of birds on it appears in Silent Hill: Shattered Memories, as a Shout-Out to the original game.
• Star Fox Adventures: Despite its strong inspiration in The Legend of Zelda games, the trope only occurs once in this game. After Fox retrieves the Gold Fruit to its owner in SnowHorn Wastes, he initiates a test where he has to play the Dinosaur Horn while standing on pads located strategically in key parts of the region, and do so before time runs out (it's recommended to clear the associated paths before starting to save time later). Once he succeeds, the gate to the next Krazoa Shrine opens.
• Startropics has a giant organ with eight keys, representing the notes of a musical scale. The solution comes from a parrot that says "Do me so far, do me?" This, of course, means playing "Do Mi So Fa Do Mi" on the organ.
• One of the adventure games in the Trapped series (not The Trapped Trilogy, the Trapped Series) requires you to play the tune from a music box on the piano to open a secret door.
• Several times in the Ultima series, the Avatar has to play a simplified version of the song 'Stones' in order to gain a Plot Coupon or MacGuffin.
• An optional puzzle in Undertale features this, where you must play the first few notes of a tune heard in a room a little bit ahead on a piano. The reward's only barely worth it, though.
• Wonder Boy in Monster World requires you to remember short ocarina sequences to open the doors in the first dungeon.
• Frequently in Zork Nemesis, since the element of water is associated with music and the alchemist of water was a music teacher. The first one is a fountain which can be opened by turning on streams of water which correspond to the notes in a melody played on pan pipes.

Webcomics

• The MS Paint Adventures series Problem Sleuth has the same puzzle as Resident Evil as a Shout-Out. It also plays with this trope by occasionally literally using musical instruments as security measures (eg. wedging a door shut with an oboe) - at one point "security measures" is even Pot Holed to a Google Image Search for "woodwind instruments".

Web Original

• In the lonelygirl15 story "lonelygirl15 Season One Finale", the door to the Order base would only open if certain musical notes were played in sequence.

Western Animation

• Alvin and the Chipmunks once got press-ganged into traversing an ancient temple, with traps that get disabled through singing. It seems, though, that any song will do as long as it's in chipmunk voices, since a second group of chipmunks go through it later by singing a completely different song than Alvin and his brothers did earlier.
• Batman: The Animated Series:
  • The episode "The Cat and the Claw" featured one of these where the keys of a piano had to be pressed in the right order - the first few bars of Beethoven's Ode to Joy - to open a secret door. Catwoman, having had piano lessons, played that out with ease and then continued...showing the hidden parts of the room.
  • In "If You're So Smart, Why Aren't You Rich", another puzzle, this one courtesy of the Riddler, featured a door and three keys, labelled "A", "C" and "D". Batman tries the "D" key, which releases two saw blades that he and Robin dodge. He's about to try the "A", when Robin stops him saying that will release three blades. This is because they are based on major scales; the scale in the key of C has no sharps, and safely opens the door.
• DuckTales (2017): In "The Secret(s) of Castle McDuck!", Dewey and his brothers follow a note left by their Missing Mom Della, one part of which involves using the string of an old bow to play the notes "B", "A", and "G".
• In the Foster's Home for Imaginary Friends episode "The Big Cheese", no one knows the combination to disable the new security system. No one, that is, except Cheese, who is singing the beeps the keypad made when it was entered. Hilarity Ensues as the others try to figure out the combination one note at a time.
• Infinity Train: In "The Crystal Car", Tulip, One-One and Atticus find that the exit door from the titular car is locked and inaccessible. The only way to get the door unlocked and a new staircase placed is by singing an emotional song. It turns out that the song has to specifically be one that has personal meaning to the singer, and Tulip is mortified when she ends up having to sing "Word Up" by Cameo, which she used to sing with her parents on road trips.
• An episode of Jimmy Two-Shoes had Heloise enter her secret lab in the Absurdly Spacious Sewer by tap-dancing in rhythm on a manhole.
• Josie and the Pussycats in Outer Space, episode "The Hollow Planet". A prison door unlocks when a whistle with a specific pitch is blown twice.
• Scooby-Doo:
  • One episode involved an organ, and the phrase "feed the organ" to open a secret passage. Which was also the sequence, "F", "E", "E", "D" keys.
  • Another episode, "Phantom of the Country Music Hall", had a musical code "FEBAG" that opened a secret passage. And yet another episode had the villain's name, Ace Decade, spelled out in a piece of sheet music. Scooby-Doo likes this trope.
• In Scooby-Doo! Mystery Incorporated, Mr. E opens his vault by playing the first few notes of his signature theme.
• An episode of The Simpsons which parodied The Da Vinci Code features Lisa on a hunt to find a mysterious treasure guarded by an order of nuns. A clue to the treasure informs seekers to devote themselves to God with "heart and soul"; Lisa realizes that this is a reference to the song of the same name and plays it on the convent's organ, activating a Rube Goldberg Machine that reveals the next part of the puzzle.
• South Park:
  • In the episode "Towelie", Towelie attempts to remember the code to enter the "Secret Government Base". The buttons make a noise as they are pressed and Towelie plays the tune to "Funky Town". Which doesn't open the door.
  • The episode "Imaginationland" uses this as an Overly Long Gag. Whoever wants to travel to the idyllic world of imaginary characters must sing its name multiple times and with a very precise tempo and tone, or else it won't work.
• Steven Universe: "The Test" has this in Pearl's room, where Steven must step on four lights in the correct order to open up the stairs. Afterwards, he must then dodge swinging axes. When Steven finds out that Garnet's room was rigged, he returns to Pearl's room and found out that the axes phase through him, and that the same panels always allow the stairs to open regardless if he steps on the right panels or not.
  Steven: It didn't even matter?!
• Appears prominently in the TaleSpin two-parter "For Whom the Bell Klangs". The ancient civilization of Tinabula based all its technology around sound, including the sonic superweapon that Klang is after, as well as the city's self-destruct mechanism. Unsurprisingly, they encounter a door early on that is meant to open with a precise musical note: archaeologist Katie Dodd has the perfect pitch necessary to open it, but the hapless mook who tries first isn't so lucky.
  Klang: "She said 'B', not 'B Flat'!"
• In Xiaolin Showdown, the vault for the Shen Gong Wu is opened by playing specific notes on wind chimes.

Real Life

• Averting this trope in Real Life is why tonal keypads at ATMs don't use different pitches for each number, preventing eavesdroppers from copying other peoples' PINs by sound.
• If you use a phone number a lot, eventually you'll be able to tell if you've entered a wrong digit by sound alone.
• The earliest hackers (known as Phreakers) would use a tone of 2600 Hz which caused a telephone switch to think the call was over, leaving an open carrier line which could be exploited to provide free long-distance and international calls. The tone was discovered in approximately 1957, by Joe Engressia, a blind seven-year old boy. Engressia was skilled with perfect pitch, and discovered that whistling the fourth E above middle C (a frequency of 2600 Hz) would work. For extra fun, free whistles given out in Cap'n Crunch cereal boxes also produced a 2600 Hz tone when blown. An electronic gadget for doing this was the first product that Apple co-founder Steve Wozniak ever sold.

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