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[[quoteright:275:[[ComicBook/DisneyDucksComicUniverse https://static.tvtropes.org/pmwiki/pub/images/bonnie_4.png]]]]
[[caption-width-right:275:If you're tone-deaf, you're out of luck.]]
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->''"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 HiddenInPlainSight. The tune itself may be significant/ironic, or the [[DiegeticSoundtrackUsage Theme Tune]] or {{Leitmotif}} of a character.

Subtrope of SolveTheSoupCans. Compare with MusicalTrigger. Can be related to OnlySmartPeopleMayPass, if actual musical ability is required. SisterTrope to OpenSesame, when the password is a spoken phrase.

----
!!Examples
[[foldercontrol]]

[[folder:Anime & Manga]]
* In ''Anime/MyOtome'', a specific song, from which each of the three main characters knows one verse each, is one of the three requirements for activating [[spoiler:the Harmonium]].
[[/folder]]

[[folder:Comic Books]]
* In the 60s ''ComicBook/{{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.
* ''ComicBook/DisneyDucksComicUniverse'':
** In a ''Scrooge [=McDuck=]'' story by Creator/CarlBarks that's a riff on ''Literature/TheHunchbackOfNotreDame'', 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 (ItMakesSenseInContext), 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 ''WesternAnimation/DuckTales1987'' comic written for ''Magazine/DisneyAdventures'' 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, [[VoiceChangeling who's good at impressions...]]
* One shows up in Creator/WarrenEllis' ''Comicbook/IgnitionCity'', triggered by the owner's favorite song - "[[https://www.youtube.com/watch?v=kyofs0mreCc A Nightingale Sang In Berkeley Square]]".
* In one issue of ''Comicbook/TheIncredibleHulk'' the Leader's time machine is programmed by playing a piano keyboard.
* In one issue of the ''Muppet Babies'' comic [[note]]Based on WesternAnimation/MuppetBabies1984[[/note]], 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.
[[/folder]]

[[folder:Film -- Animated]]
* ''WesternAnimation/DespicableMe2'': The entrance to El Macho's lair is protected by the tune of "La Cucaracha." HilarityEnsues as Gru tries to play the tune and his nacho sombrero hinders him every step of the way.
* ''WesternAnimation/MonstersVsAliens'': The security lock to the central core of Galaxar's ship is protected by a musical sequence which seems to be right out of ''VideoGame/DanceDanceRevolution''.
[[/folder]]

[[folder:Films -- Live-Action]]
* In ''Film/BatmanBegins'', the Batcave is accessed from Wayne Manor by playing a specific sequence of keys on the piano. This is carried over to ''Film/TheDarkKnightRises''. It does not, however, happen in ''Film/TheDarkKnight''; a different "Batcave" is in use in that film, due to Wayne Manor being under reconstruction.
* In ''Film/TheGoonies'', a creepy pirate organ opens a door or collapses the floor depending on whether you play the right tune or not.
* In ''Film/HudsonHawk'', 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).
* ''Film/JamesBond''
** In ''Film/ForYourEyesOnly'', 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 ''Film/TheSpyWhoLovedMe'' (2 films earlier); it is less obvious, though, because Q stops after 5 notes and Film/JamesBond fills in the final 2 a few seconds later.
** In ''Film/{{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 ''Film/CloseEncountersOfTheThirdKind''.
* In ''Film/Paddington2'', 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 ''Film/{{Prometheus}}'', the Engineers' ship is activated by pressing buttons in order and by playing notes on a flute-like instrument.
* The film adaptation of ''Film/RichieRich'' 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 [[spoiler:that contains valuable mementos, not real valuables]]). The parents only sing the rest of the verse out of nostalgia and [[SickeninglySweethearts a need to be saccharine]].
* The movie ''Film/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 ''Film/WhatACarveUp'', Ernie [[LuckBasedSearchTechnique accidentally activates the secret door]] in the music room by pulling out the stops on the organ while Syd is searching the walls.
* ''Film/WillyWonkaAndTheChocolateFactory''. 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 [[KnowNothingKnowItAll Mrs. Teavee]] claims.
* In ''Film/YellowHairAndTheFortressOfGold'', 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.
[[/folder]]

[[folder:Literature]]
* In book two of ''Literature/The39Clues'', the search for the Clue eventually leads Amy and Dan to [[spoiler: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 [[spoiler: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 ''Literature/AtlasShrugged'', although it's not sung. Backed up with SelfDestructingSecurity for anyone who tries to force their way in.
* In ''Killashandra'', part of Creator/AnneMcCaffrey's ''Literature/CrystalSinger'' 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 Literature/JamesBond in ''Literature/DevilMayCare'' is sent for a mission to Afghanistan on the behalf of the BigBad, 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 ''Literature/TheMouseWatch'', [[BigBad 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".
* ''Literature/OldKingdom'': 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 [[spoiler:except when all the bells are rung together]] (it sends the ringer into Death).
* Pops up ''everywhere'' in Sharon Shinn's ''Literature/{{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 UnReveal.
[[/folder]]

[[folder:Live-Action TV]]
* An episode of ''Series/{{Chuck}}'' involved a hidden compartment opened with a high C note. [[spoiler:Casey uses his choir-boy background to produce the note.]]
* ''Series/{{CSI}}'': In "Suckers", they investigated the robbery of a hotel vault. At the end Grissom realises that [[spoiler:the lock was programmed so the tones of the numerical keys would tap out the melody for "Three Little Maids From School" from ''Theatre/TheMikado''. A tune that would be familiar to the thieves; the manager was co-operating with them to carry out an insurance scam]].
* ''Series/DoctorWho'': In "[[Recap/DoctorWho20thASTheFiveDoctors The Five Doctors]]", the Fifth Doctor played a harp to get into the villain's lair. The tune itself was HiddenInPlainSight.
* In one episode of ''Series/KyleXY'' 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 ''Series/{{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 ''Series/{{MacGyver|1985}}'' ("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 ''Series/TheMole'' 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.
* ''Series/MurderSheWrote'': In "A Murderous Muse", the killers set up a system whereby when the VictimOfTheWeek plays a certain chord on the piano, it unlocks the secretary behind him and fires the gun hidden within.
* ''Series/{{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 ''Series/StargateAtlantis'', Janis, an Ancient scientist, used three different tones played in order to hide his secret lab.
* ''Series/StarTrekTheOriginalSeries'': in "[[Recap/StarTrekS3E3TheParadiseSyndrome The Paradise Syndrome]]" the obelisk left by the {{Pre|cursors}}servers 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.[[/note]]
* ''Series/StarTrekPicard'': In a callback to "[[Recap/StarTrekTheNextGenerationS1E1EncounterAtFarpoint Encounter At Farpoint]]", [[spoiler:Moriarty]] is deactivated by whistling "Pop Goes The Weasel".
* ''Series/Titans2018''. Near the end of season one, Dick Grayson [[ItMakesSenseInContext 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 ShoutOut to the ''Film/BatmanBegins'' and ''Film/TheDarkKnightRises'' examples in the Live Action Film section.
* In the ''Series/WhiteCollar'' 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.
* ''Series/WonderWoman''. 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.
[[/folder]]

[[folder:Radio]]
* One ''Radio/AdventuresInOdyssey'' 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.
[[/folder]]

[[folder:Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons''
** 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 PlayerCharacter 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 Gate}}s 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.
** ''Magazine/{{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 ''TabletopGame/{{Planescape}}'', gates to other planes can be opened this way.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/TheSeventhGuest'' has one [[https://www.youtube.com/watch?v=9nSDedyBnzg&feature=search shown here]] involving a piano. Technically, though, it's more of a [[SimonSaysMinigame Simon Says puzzle]] in this case.
* ''VideoGame/AlidaTheEnigmaticGiant'': 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 ''VideoGame/AnotherCode'' 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 ''VideoGame/{{Aquaria}}'', Naija uses her songs to [[VoluntaryShapeshifting 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 [[spoiler: Li's cage near the end of the game]].
* In the text adventure ''VideoGame/AugmentedFourth'', 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 ''[[VideoGame/BaldursGate Baldur's Gate: Dark Alliance II]]'', you have to open a secret passage by playing a harpsichord.
* ''VideoGame/BrutalLegend'' has various Guitar riff sequenced that activate certain powers, up to and including opening new areas.
* In ''VideoGame/ChronoCross'', each element has a unique tone when cast in battle. Playing [[spoiler: the Song of Life]] with these tones when fighting the FinalBoss will instantly win the battle and free [[spoiler: 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 ''VideoGame/ChronoTrigger'' playing an organ always reveals hidden doors.
* Getting through one BonusDungeon in ''VideoGame/CosmicStarHeroine'' requires playing a sequence of notes on a piano. In practice this is a simple LockAndKeyPuzzle as you don't personally choose any notes, you simply need to find a piece of paper and then get to the piano.
* ''VideoGame/DreamChronicles'' 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 ''VideoGame/TheElderScrollsIIIMorrowind'', 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.
* ''VideoGame/EternalDarkness: Sanity's Requiem'' has you play one song three times: twice on an organ, once on a piano.
* ''VideoGame/EternalSonata'' has you play increasingly long portions of [[spoiler: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.
* ''VideoGame/{{Fallout 3}}'''s quest Tranquility Lane, set in a LotusEaterMachine, 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 ''VideoGame/FalloutNewVegas: 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 ''VideoGame/FinalFantasyII'', 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.
** ''VideoGame/FinalFantasyVII'' has the final LimitBreak for Tifa that is obtained by playing the right notes on the piano.
** ''VideoGame/FinalFantasyVIII'' has an organ that needs to be played to open a gate.
** A dungeon in ''VideoGame/FinalFantasyIX'' has bells as InterchangeableAntimatterKeys.
** ''VideoGame/FinalFantasyX2'' has a puzzle involving repeating notes.
* ''VideoGame/GoatSimulator3'': The locked mausoleum can be opened by playing "[[Franchise/StarWars The Imperial March]]" on the bell tower's bells.
* Near the end of ''VideoGame/GodOfWarIII'', there's a puzzle that doesn't even bother trying to hide what it is, as the "notes" are copies of the Platform/PlayStation's four main buttons and the tune you play is the franchise's {{leitmotif}}.
* ''VideoGame/IllusionOfGaia'' requires protagonist Will to play specific tunes on his flute to open several gates.
* The main objective in ''VideoGame/ImpossibleMission 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.
* ''VideoGame/TheJourneymanProject 3'' has a set of Buddhist Prayer Wheels on which the player must playt a prayer chant. [[spoiler:One of them is squeaky and must be oiled first.]]
* ''VideoGame/KingsQuestIVThePerilsOfRosella'' 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).
* ''VideoGame/KingsQuestVIIThePrincelessBride'' 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 ''VideoGame/LawnmowerMan'' 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.
* ''Franchise/TheLegendOfZelda'':
** ''VideoGame/TheLegendOfZeldaOcarinaOfTime'': 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 [[PlatformActivatedAbility 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.
** ''VideoGame/TheLegendOfZeldaMajorasMask'': 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 [[WarpWhistle warped you to the temples' whereabouts]].
** ''VideoGame/TheLegendOfZeldaTheWindWaker'': 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.
** ''VideoGame/TheLegendOfZeldaSpiritTracks'': 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.
** ''VideoGame/TheLegendOfZeldaSkywardSword'': 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 [[spoiler:the Silent Realm area of Skyloft and also holds the key to unlock the final dungeon in the game]].
** ''VideoGame/TheLegendOfZeldaBreathOfTheWild'': Compared to previous games, the game has a reduced presence of this trope. One of the [[MiniDungeon 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.
* ''VideoGame/{{Loom}}'s'' MagicMusic starts you off with the "Opening" draft, which works as a universal one of these (where [[ThePasswordIsAlwaysSwordfish The Password Is Always]] E-C-E-D).
* In ''VideoGame/TheLostCrown'', 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 ''VideoGame/LufiaIIRiseOfTheSinistrals'' where you have to step on "musical note" tiles in a certain order to open the locked doors.
* ''VideoGame/LuigisMansion3'': One of the collectible gems is unlocked by using the air from Luigi's [[WeaponsThatSuck Poltergust]] to play the franchise's main melody on a group of bottles.
* ''VideoGame/LunarTheSilverStar'' 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 DreadfulMusician duo, while Nash is too worried about stepping on Mia's notes to harmonize.
* ''VideoGame/{{Myst}}'':
** The Selenitic Age Descriptive Book is accessed via a five-note combination. Then to enter TheMaze, 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 ''VideoGame/{{Riven}},'' the combination to unlock Catherine's cell is revealed by listening to [[spoiler: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 [[GuideDangIt will figure it out eventually]].)
** ''VideoGame/MystIVRevelation'' 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 [[spoiler: 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.
* ''VideoGame/NancyDrew'' '''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'')
** [[BizarreInstrument An entire set of stairs]] (''Blackmoor Manor'')
* The drawbridge passtune in ''VideoGame/NetHack''. You find it out by either playing Mastermind or by having your god tell it to you.
* At one point in ''VideoGame/TheNeverhood'', 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.
* ''VisualNovel/NineHoursNinePersonsNineDoors'': 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 ''VideoGame/{{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...
* ''VideoGame/PhantasyStarII'': 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.
* ''VideoGame/PrinceOfPersiaTheSandsOfTime''. In the GBA version, there are several levels that are passed by playing a certain tune in a certain sequence.
* ''VideoGame/ResidentEvil'' 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 ''VideoGame/ReturnToMysteriousIsland'' 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).
* ''VideoGame/SacredEarthPromise'': 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.
* ''VideoGame/{{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.
* ''VideoGame/SchizmMysteriousJourney'' 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.
* ''VideoGame/{{Seiklus}}'' uses a giant piano. The keys are colored, and you have to jump on them in a sequence [[EnterSolutionHere found elsewhere.]]
* Such a puzzle exists in ''VideoGame/SilentHill1'', 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 ''VideoGame/SilentHillShatteredMemories'', as a ShoutOut to the original game.
* ''VideoGame/StarFoxAdventures'': 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 [[MiniDungeon Krazoa Shrine]] opens.
* ''VideoGame/{{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 ''VideoGame/TheTrappedTrilogy'', the ''VideoGame/TrappedSeries'') requires you to play the tune from a music box on the piano to open a secret door.
* Several times in the ''VideoGame/{{Ultima}}'' series, the Avatar has to play a simplified version of the song 'Stones' in order to gain a PlotCoupon or MacGuffin.
* An optional puzzle in ''VideoGame/{{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. [[spoiler:The reward's only barely worth it, though.]]
* ''VideoGame/WonderBoyInMonsterWorld'' requires you to remember short ocarina sequences to open the doors in the first dungeon.
* Frequently in ''VideoGame/ZorkNemesis'', 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.
[[/folder]]

[[folder:Webcomics]]
* The ''Webcomic/MSPaintAdventures'' series ''Webcomic/ProblemSleuth'' has the same puzzle as ''VideoGame/ResidentEvil'' as a ShoutOut. It also [[ZigZaggedTrope plays with]] this trope by occasionally ''literally'' using musical instruments as security measures (eg. wedging a door shut with an oboe) - [[http://www.mspaintadventures.com/?s=4&p=001649 at one point]] "security measures" is even {{Pot Hole}}d to a Google Image Search for "woodwind instruments".
[[/folder]]

[[folder:Web Original]]
* In the ''WebVideo/{{lonelygirl15}}'' story "lonelygirl15 Season One Finale", the door to the Order base would only open if certain musical notes were played in sequence.
[[/folder]]

[[folder:Western Animation]]
* ''WesternAnimation/AlvinAndTheChipmunks'' 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.
* ''WesternAnimation/BatmanTheAnimatedSeries'':
** 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. [[spoiler: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.
* ''WesternAnimation/DuckTales2017'': In "The Secret(s) of Castle [=McDuck=]!", Dewey and his brothers follow a note left by their MissingMom Della, one part of which involves using the string of an old bow to play the notes "B", "A", and "G".
* In the ''WesternAnimation/FostersHomeForImaginaryFriends'' 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. HilarityEnsues as the others try to figure out the combination one note at a time.
* ''WesternAnimation/InfinityTrain'': In [[Recap/InfinityTrainS1E4TheCrystalCar "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. [[spoiler: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 Music/{{Cameo}}, which she used to sing with her parents on road trips.]]
* An episode of ''WesternAnimation/JimmyTwoShoes'' had Heloise enter her secret lab in the AbsurdlySpaciousSewer by tap-dancing in rhythm on a manhole.
* ''WesternAnimation/JosieAndThePussycats in Outer Space'', episode "The Hollow Planet". A prison door unlocks when a whistle with a specific pitch is blown twice.
* ''WesternAnimation/ScoobyDoo'':
** 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. Franchise/ScoobyDoo ''likes'' this trope.
* In ''WesternAnimation/ScoobyDooMysteryIncorporated'', Mr. E opens his vault by playing the first few notes of his signature theme.
* An episode of ''WesternAnimation/TheSimpsons'' which parodied ''Literature/TheDaVinciCode'' 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 RubeGoldbergMachine that reveals the next part of the puzzle.
* ''WesternAnimation/SouthPark'':
** 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 OverlyLongGag. 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.
* ''WesternAnimation/StevenUniverse'': [[Recap/StevenUniverseS1E38TheTest "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 ''WesternAnimation/TaleSpin'' two-parter "For Whom the Bell Klangs". The ancient civilization of [[MeaningfulName Tinabula]] based all its technology around sound, including [[spoiler: the sonic superweapon that [[BigBad 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:''' "[[{{Pun}} She said 'B', not 'B Flat']]!"
* In ''WesternAnimation/XiaolinShowdown'', the vault for the [[MacGuffin Shen Gong Wu]] is opened by playing specific notes on wind chimes.
[[/folder]]

[[folder:Real Life]]
* Averting this trope in RealLife is why tonal keypads at [=ATM=]s ''don't'' use different pitches for each number, preventing eavesdroppers from copying other peoples' [=PIN=]s 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, [[DisabilitySuperpower 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, [[FreePrizeAtTheBottom 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 Creator/{{Apple}} co-founder Steve Wozniak ever sold.
[[/folder]]

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