These are songs or themes which start with one instrument, and then the rest of the instruments appear up to two at a time. The voice may appear (or not) at any point of the song in question, either at the beginning, in the middle, or as the last instrument.
For example, in a four-piece ensemble composed of guitar, bass, drums and keyboard, you may have the drums play a beat, then the bass joining in order to shape the song, then the keyboards to add ambience to it, and finally the guitar joins in for the full explosion before the lyrics start.
This is a common happening in live performances, where each musician is introduced with their respective instrument by the main singer, then the singer himself is introduced by another singer, usually one that plays an instrument.
Compare Variable Mix, where the music in a game gradually evolves based on what's happening in the game. Also compare Big Rock Ending, where every instrument ends the song in a big note, disappearing one at a time. Not to be confused with Explosive Instrumentation, which is a very different trope.
- Several whole genres of composition, such as the Round, the Canon, and the Fugue, are specifically designed to have the voices enter one at a time, imitating the notes from the previous parts. They're designed in such a way that the harmony arises naturally as each voice is added. You can try it yourself by getting together a couple friends and singing "Row, Row, Row Your Boat," "Frére Jacques," or the like.
- Da Vincis Notebook opens their cover of "Stuck in the Middle with You" with a vocal version, one at a time.
- During the Renaissance Music era it was a common pastime for groups of friends (or drinking buddies) to sing elaborate "Catches", usually Drunken Songs and often Bawdy Songs, on the principle of Rounds where each voice imitates the previous one as it enters. In many cases they were composed cleverly so that a secret message would be revealed in the combined voices by highlighting syllables that would appear innocent on the page. (One infamous example makes very naughty use of the phrase, "In a country churchyard...")
- "Sumer Is Icumen In" (in modern English, "Summer has come in") is a 13th-century composition for six voices, four of which enter in a round one after the other.
- Live's "Lightning Crashes". It starts with the guitar, then at 0:26 the vocals, then 1:58 the bass, and finally at 2:27 the drums appear.
- The Cure' "Just Like Heaven" starts with the bass, then drums come in, then the guitar, keyboards and finally the vocals by Robert Smith.
- "The Examination" by His Name Is Alive starts with just synths, then gradually adds in guitar, bass, and drums with each measure, ending with the vocals.
- Talking Heads does this over the course of several songs in their concert film Stop Making Sense, introducing each member of the band in turn. The first song is just David Byrne on guitar (with a drum machine providing a beat). Tina Weymouth (bass) comes out for the next song, then Chris Frantz (drums), and then Jerry Harrison (second guitar). Then the fifth and sixth songs introduce some guest musicians (percussion, keyboard, and two soul singers), and that fully expanded band plays for the rest of the concert.
- Pepe Deluxé's "Queenswave" (off the album Queen of the Wave) begins with an ambient synth and acoustic guitar, then gradually adds bass, a single cymbal, an electric organ, bells, a full drum kit, a flute, an electric guitar, and for the song's climax, a Tesla coil.
- The Young Persons Guide To The Orchestra by Benjamin Britten is explicitly designed to do this, starting with the full orchestra, then breaking it down section by section and instrument by instrument (with accompanying narration in some versions) to demonstrate how the entire sound of an orchestral movement is constructed.
- Maurice Ravel's "Boléro" was inspired by Russian actress and dancer Ida Rubinstein. It starts with a flute and keeps adding more and more instruments, in essence just one melody repeated over and over again for 15 minutes, but it's one of the most popular and exciting compositions of all time.
- Pachelbel's Canon: The "canon" in the name indicates a form where each instrument enters one at a time, following the previous instrument by a set number of beats but playing the exact same notes, which are composed in such a way that they harmonize exactly.
- The Fugue is a related form widely used in Baroque Music, similar to the canon in that each voice enters one at a time, but imitating each other rather than always playing the same literal notes. The most famous examples are by Johann Sebastian Bach, although many other composers before and after him have tried their hands at it.
- The first movement of "Jeux venétiens" by Witold Lutosławski consists of eight alternating fast and slow sections, each of which commences and terminates with an identical percussive clap. The fast sections have all the musicians playing more or less independently of each other, but from the same parts, for a specified number of seconds. Only the woodwinds play during Section A; Section C has kettledrums playing along with the winds; (muted) brass are added to the mix in Section E; and the piano plays with all of the foregoing in Section G.
- Inverted for comic effect in Joseph Haydn's "Farewell Symphony." The final movement concludes with the instruments dropping out one at a time, extinguishing their lights and leaving the stage, until at the end there are just two muted violins playing. The story goes that Haydn wrote the piece to let his boss, Prince Nicolas Esterházy, know that the musicians felt they had stayed too long at his summer residence and were ready to go back home. The prince took the hint and they returned home the next day.
- The Bonzo Dog Band's "The Intro and the Outro" is three minutes of lampshading this, endlessly introducing one ridiculous instrument after another.
- Neil Cicierega' "The Starting Line" is (almost) entirely built from samples of various songs' opening lines. At the beginning, the samples are introduced one by one, gradually building up the sound collage that forms the main part of the song.
- All of Orbital's music is structured like this. Samples are gradually added to the track, one by one, until they are all playing in crescendo. Samples are then removed one by one to reveal a new background sample underneath, and the process starts again - now using a mixture of both familiar and completely new samples. This happens repeatedly throughout a track, with the crescendos becoming more intense each time. The climax ends with samples leaving the track one by one until none remain. "The Girl with the Sun in Her Head" is a straightforward example of the technique.
- Mike Oldfield's "In Dulce Jubilo" opens with a guitar, then a recorder melody backed by guitar and piano, with additional instruments being introduced each time the melody repeats.
- Extremely common in instrumental folk music, especially Celtic; a tune may be started with wind instrument, have percussion added in the second movement, strings in the third, and bagpipes for the full crescendo.
- Bauhaus' song "Bela Lugosi's Dead". Starts with a drum beat, then the bass joins, then the guitar slowly comes, then the voice appears.
- Death Cab for Cutie do this in "I Will Possess Your Heart." It starts with a pair of piano bars, then the bass joins, then the guitar appears subtly, then the drums join, then after a very long intro, the voice joins at the end.
- A favorite tool of The Naked and Famous. Showcased quite nicely in "Girls Like You"; the vocals start right away, but another instrumental track is layered in every few measures, building the song from a quiet start to a banger of an album closer.
- Chatmonchy - "Shangurira", starting with drums, adding cymbals, then bass, then guitars, then vocals.
- Alestorm's "Buckfast Powersmash": guitar > drums > keyboards > bass > voice.
- The Dark Element's "Someone You Used to Know" starts with just Anette and a piano and gradually adds in other instruments until the whole band is playing soft rock by about the three-minute mark.
- Iron Maiden's "The Clairvoyant": bass > guitar 2 > guitar 1 > drums > voice.
- Limp Bizkit's "Take A Look Around" has the following starting sequence: guitar > bass > drums > DJ > vocals.
- On Nightwish's album, Dark Passion Play, the last song, "Meadows of Heaven", starts with just a single instrument and a voice, and builds up into a grand finale with the whole orchestra and choir and band.
- Sly and the Family Stone has each performer introduce his own instrument in "Dance to the Music."
- Alter Bridge's "Metalingus" starts with bass, drum and guitar doing an intro then the voice joins. In live performances, this intro starts with the drums, then the bass joins, then the guitars, and once the song exploded, the voice joins.
- "Nightclubbing" by Iggy Pop begins with drums/percussion alone, then adds keyboards, bass, various electronic instruments, and piano.
- "Celebrate" by Kid Rock: starts with drums, then keyboards and bass, then guitars, then voice.
- "New Orleans" starts with what sounds like a drum sample, then guitars, then trumpet, then voice, then sax, then piano and claps, and finally the rest of the band.
- "Stairway to Heaven" by Led Zeppelin. It starts with an acoustic guitar, then flutes are added after the first bar, then after several more bars Robert Plant starts singing. After several bars, the acoustic bass enters, and halfway through the lengthy 8:03 song, the drums finally kick in.
- The Who's "Baba O'Riley". It starts with a synth, then a guitar piece, then the drums, then the bass, and finally Roger and later Pete.
- The Doors "Wild Child" starts with guitar, then drums, then bass, then keyboard, then finally Jim keys in.
- Dire Straits "Walk of Life" does this for a full minute before the vocals begin. It starts with the keyboard playing background chords, then an acoustic guitar strums single chords while the keyboard begins playing the hook and the drummer taps the hi-hat, then the drummer goes into the full rhythm and the electric guitar and bass join in, and finally the vocalist completes the ensemble.
- "Memphis Soul Stew," by King Curtis, which is also performed on The Simpsons Sing the Blues as "Springfield Soul Stew," introduces each part separately.
- At the climax of Beck, everyone but Koyuki has given up, so he is left on his own on stage, and begins to play without the rest of the band. Inspired, one by one the rest of the band joins in, building on the song this way. The song in the original Japanese audio was The Beatles' "I Got A Feeling," but it was changed for the dub.
- The Little Mermaid's "Kiss the Girl", where the various animals jump in one at a time.
- "Trashin the Camp / Doo Bad Shi Doo" from Disney's Tarzan, in which some playful gorillas and an elephant find a human camp and use the random objects they find there to play a (very destructive) impromptu song.
- "Hedwig's Theme" from the Harry Potter series opens with a celeste solo, after which the rest of the orchestra is brought in gradually: first the strings, followed by the woodwinds, and finally the brass.
- A rare literary example, the Song of Iluvatar in J. R. R. Tolkien's The Silmarillion is described as this. Each of the Valar adds their voice to the rest, one by one, and Iluvatar adapts the song to fit each new voice, including Melkor when he attempts to turn it into a dirge...
- The one-episode Fake Band in Even Stevens planned to play their debut concert on the school roof, but each member dropped out for various reasons and only Lewis (drummer) showed up. Refusing to let the band die, he proceeds to play the beat and sing his vocals until the other members join in one-by-one.
- Happens twice in Conker's Bad Fur Day:
- The Bomb Run music, heard while Conker is taking a large Cartoon Bomb from the Rock Solid clubhouse to the heart of the Uga Buga volcano, gradually adds notes from different instruments as the character approaches the required destination (bagpipes at first, piano, drums). It culminates with the addition of a tense, fast-paced African Chant.
- After Conker defeats the Experiment (and the Little Girl controlling him), he has to escape from the Tediz island before it explodes. The Countdown music will start playing and, the closer Conker gets to the coast, the more intense it gets and more instruments are added (marching drums at first, cymbals, synthetized trumpet sounds). Once Conker reaches the coast, it's replaced altogether by military reprise of the game's standard boss music.
- Done in Golden Sun: Dark Dawn during the start of the Grave Eclipse, where the soldiers inside the opera house notice that the music from the orchestra pit is getting more and more instruments included, getting ambushed by monsters at the end.
- The Temple level of Journey is a tower, which you ascend by activating light emitters at its core, one floor at a time. Each time you light up a floor, additional instruments join the background music, starting from complete silence at the start of the level and going to the full orchestra by the time you reach the top.
- The Legend of Zelda:
- This can be done optionally in The Legend of Zelda: Link's Awakening by playing the Wind Fish's Ballad in front of its egg before all of the Siren's Instruments are obtained. Each instrument will materialize and play its own separate section of the ballad, with or without the necessary accompaniment.
- In The Legend of Zelda: Majora's Mask one minigame features Link performing a music test in the milk bar. As he assumes each of his four forms and plays their respective instruments, an illusion of the previous forms playing their parts appears and the music gets more complicated as instruments are added. Finally all four Links are somehow on stage playing at once. See this here.
- A dynamic example in The Legend of Zelda: Spirit Tracks: As more sections of the tower become accessible, the music that plays in higher sections contains more instruments.
- The Legend of Zelda: Breath of the Wild: Each Divine Beast has its own introductory theme as you enter it for the first time, which changes completely the moment Link activates the Beast's first terminal. From then on each terminal activated gradually adds a new layer to the lingering dungeon theme until all five terminals are activated, and from then the song's tempo is bumped up to increase the tension before entering the boss room.
- The menu music from Mario Kart Wii adds a new instrument as you move from one page of the menu to the next.
- In NieR: Automata, the final version of "The Weight of the World" ending theme, which plays over Ending E, starts off with a simple Chip Tune leitmotif, before adding more instruments, then the vocals, and finally a choral as certain plot events unfold.
- Night in the Woods features certain levels where you search for four ghosts. Each area starts off silent, but as you locate each one, they'll begin playing an instrument, until the entire band is performing.
- In Persona 3, the music in Tartarus works like this. The first block (of 6) has a simple beat in the background. Each new block has an additional instrument added.
- In Pokémon Black and White, as you pass the Badge Gates for Victory Road more instruments get added to the song until the full Victory Road theme starts playing.
- In Super Smash Bros. for Wii U, the remix of "Escape" from Metroid starts with the original 8-bit chiptune, then gradually adds in a couple orchestral instruments every few bars. By the song's third loop, it's a full orchestra.
- During the final leg of the trip to meet the Disc-One Final Boss, Undertale's titular track begins with acoustic guitar, which is slowly joined by a gentle electronic beat, piano, strings, flute, and drums as characters onscreen explain the events that kicked off the plot. Each of these, in turn, fade out at the end of the song.
- Xenoblade Chronicles:
- Zanza's theme in the final boss fight starts with a voice, then adds an electric guitar, then a piano, then a violin. it works surprisingly well.
- The god-slaying sword plays in the same boss fight and starts with an organ, adds a choir, adds bells, strings, and then brasses.
- The Level Select theme of all Yoshi's Island games adds an instrument for every world completed.
- Homestuck tie-in album "The Felt" features "Omelette Sandwich", a song about a character who repeatedly travels back in time to amass an army of himself whenever he needs to fight. True to form, the song itself periodically "rewinds", layering in new instruments and speeding up each time to reflect how the character grows more frenzied as he brings in more copies of himself. At the very end, the instruments cut out in the reverse order as the song slows back down.
- Homestar Runner: The toon "One two, one two". This one uniquely features a custom mixer that lets you add or remove instruments interactively.
- Potter Puppet Pals has a variant with "The Mysterious Ticking Noise", which only has one instrument — the ticking — but gradually incorporates vocals from more and more people.
- In Pocoyo, Pocoyo and friends try to make a music band by themselves, then usually one starts with an instrument and the other members added gradually until make the song complete.
- The Powerpuff Girls do it twice in the very short song "Love Makes the World Go Round," first with drums > bass > guitar, then with vocals.
- The rendition of "Dreidel Dreidel Dreidel" from the South Park episode "Mr Hankey's Christmas Classics", which layers in more and more vocal parts from various characters as it goes.