Because helium is lighter than air, when you inhale it and try to talk, the sound waves travel faster through the lower-density gas, resulting in reedy, duck-like voices that can be used to great comic effect. This can be tried in real life, although it should be noted that helium displaces oxygen in your lungs, so breathing it too long can be harmful.
Gasses that are heavier than air, such as sulfur hexafluoride and xenon, have the opposite effect, resulting in a temporarily evil- or gruff-sounding voice, but this rarely appears in fiction probably because the gas is less widely known. They're also a lot more dangerous; for obvious reasons, it's easier for a heavier-than-air gas to build up in your lungs than a lighter-than-air gas. Unless you're standing on your head.
Because it is easy, plausible in many settings, and can be very funny, helium voice often shows up in fiction.
It should be noted that contrary to popular belief, helium actually changes the timbre (as in the quality) of one's voice, not the pitch. Regardless, those who favor the easy and cheap way of getting things done or just didn't do the research still go for artificially pitch-shifting the characters' voice in spite of this tidbit.
Instant Soprano is a more-painful way to induce higher-than-normal vocal pitches in fiction.
- Used in this his Twix commercial.
- A 2003 ad for Toys R Us has Geoffrey the Giraffe making an announcement from a hot-air balloon, and he gets this because his head is too close to the helium.
- Used in a State Farm ad in which a helium truck is involved in an accident. Two grown men have fun saying "fender bender" in munchkin voices.
- The Pokémon episode "The Case of the K-9 Caper!" involved Team Rocket using the rather smart plan to disrupt the voices of an Officer Jenny and the other Trainers using helium, so their Pokémon wouldn't recognize their commands. Then they used voice changers to imitate the Trainers' usual voices. It fails because the Pokémon are able to tell who their real Trainers are in the end.
- The Cowboy Bebop episode "Waltz For Venus" features an expedition to the titular planet, whose atmosphere consists largely of helium when the series takes place. Naturally, it has the expected effect on the characters' voices.
- In episode three of Wandaba Style, The Professor's latest experiment involves the girls of MixJuice and Satellite Girl Kiku#8 taking a blimp filled with experimental helium into the stratosphere. On the way up, they end up losing most of their air supply, and Kiku replaces it with "extra" air. Unbeknownst to any of them, the air was actually some of the helium, which they find out when they're giving a concert.
- Fat Buu talks like this in the English dub of Dragon Ball Z, when in the Japanese he sounds more like a jovial old man.
- In the Robin Williams stand-up routine Weapons of Self Destruction, he states that this is the reason why we need to invent cars that run on helium. Because there would be nothing funnier than two angry guys getting out of the car after a wreck and having them going "I'm gonna kick your ass... Crap, I think one of us has a gas leak."
- An old short bit on The Dr. Demento Show ran like this:
Man: Well, first it was, y'know, just a social thing....
Interviewer: Right, mmm-hmm....
Man: ....then I found myself hangin' around supermarket openings, and kids' birthday parties, y'know, anywhere there was balloons.
Announcer: This man has a problem.
Man: And now it's every couple of hours. [sound of balloon deflating, breathing in; in helium voice] Here, y'wanna hit?
Announcer: This man is hooked on helium. Today, one in every two hundred million Americans is a habitual helium head. It may begin with a single heart-shaped balloon, but just a few birthday parties later — this could be you:
Man: I think, uh, I realized I was in trouble on Thanksgiving Day.
Interviewer: What happened then?
Man: I was at the Macy's Day Parade, and, uh, I must've blacked out or something, I don't know... next thing I know, I was a hundred feet in the air, and.... [sound of balloon deflating, breathing in; in helium voice] ...I was sucking Snoopy's tail.
Announcer: Helium. Please... just say, "No, tanks." [sound of balloon deflating, breathing in; in helium voice] A message from the National Helium Foundation.
- During Mark Waid's Fantastic Four run, a shrink-rayed Ben is combing the Baxter Building's air ducts for an alien bug. Reed, talking to him via intercom, keeps cracking up over his "little helium voice" and asks him to say "It's clobberin' time."
- In one FoxTrot strip, Jason imagines himself floating to the ceiling after inhaling helium, only to express his disappointment (in curly letters) that it only makes his voice funny.
- On The Far Side, some big dogs take turns inhaling helium balloons and barking like small dogs.
- There's a MAD gag where two men come across a vending machine labeled "A hit of helium - $1.00." The first man takes a hit and then speaks in a squeaky voice (represented by a lot of whitespace in his speech balloon). The second man, having only a quarter, puts his money in a machine labeled "Helium substitute," and a boot comes out to kick him in the 'nads, having a similar effect on his voice.
- In Ice Age 3: Dawn of the Dinosaurs, "deadly gas" turns out to be helium which, as mentioned before, can become deadly after extended periods. The characters' discovery leads to an Alvin and the Chipmunks impersonation and Hilarity Ensues. Until Buck points out the dinosaur skeletons that died laughing.
- Mune: Guardian of the Moon: When the protagonist are about to dive in the waters of the Big Blue Hole, Mune picks up some glowing fungus that he describes as rich in oxygen, and that will allow them to breathe underwater. However, as a prank the first batch he shows to Sohone are actually rich in helium, and when the big guy promptly eats one, his voice gets all squeaky.
- Used to get the voices of the Toy Story Martians, rather than artificially speeding up the voices.
- In Up, Alpha's malfunctioning collar makes him talk like this. The collar's normal voice is deep and menacing, of course.
- During the party in The Angry Birds Movie, Judge Peckinpah inhaled helium from a balloon (while floating InflatingBodyGag) and says some stuff.
- Turned on its head in the first Alvin and the Chipmunks movie: there's a scene where Alvin inhales helium, but since his voice is already high-pitched, it becomes low-pitched instead. A definitive Artistic License Physics moment, even if it is funny.
- Broadway Danny Rose: Woody Allen with a helium voice. Heh heh.
- Robin Williams has this in Club Paradise when he went diving and found out that he bought helium tanks instead of oxygen.
- In Flubber, Philip Brainard's flubber experiment causes a helium gas tank to leak open and you know what happens after that.
- In Hot Shots! Part Deux, the President of the United States, played by Lloyd Bridges, questions while diving why he brought helium instead of air — with the voice shift at an appropriate point of the Inner Monologue.
- The Martians in Mars Attacks! get the same effect from huffing a nuclear explosion. It even makes sense if it was a fusion bomb, since they work by fusing hydrogen to, well, helium.
- Max Keeble's Big Move had Robe trying to pass the time waiting for Max to arrive for his going away party by blowing up balloons to get the desired effect. As soon as he does get it, he shouts "Yee-haw!" in a very high-pitched voice, and sounds this way for the remainder of the scene.
- Police Academy 4: Citizens on Patrol has characters switching helium and oxygen bottles to play a trick on Captain Harris.
- Sneakers: Carl does this during a party at the team's HQ, much to the amusement of the other hackers.
- Who Framed Roger Rabbit: The villain does this at the end to unnerve Eddie.
- Possibly subverted in that, as Eddie explains earlier, this is actually how the villain actually sounds.
Eddie: I never did find out who that guy was. All I remember was him standing over me laughing, with those burning red eyes and that high, squeaky voice.
- Possibly subverted in that, as Eddie explains earlier, this is actually how the villain actually sounds.
- World Without Sun: The special air mix that the two guys in the underwater "deep cabin" breathe at 30 meters deep includes helium. So they get the high-pitched voice, as one researcher humorously demonstrates.
- The Eye of Argon is often read aloud this way.
- In James P. Blaylock's Homunculus, the oxygenator device spews out blasts of helium and chlorophyll whenever it's activated. Willis Pule mistakes it for another MacGuffin and steals it, only to be hit in the face by one of these blasts when he tries to open it, freaking out when he hears his own altered voice.
- In Judgement at Proteus, the fifth Quadrail Series book, Frank Compton uses this to disrupt the Shonkla-raa's ability to control the Modhri through a special hummed tone. This may have been inspired by the Doctor Who example below.
- In one Remnants book, the cast find themselves inside the body of a colossal Living Gasbag. The gases the creature runs off turn out to be helium and nitrous oxide, meaning that they not only develop helium voices but also think it's hysterically funny. They have to get out of the creature before they suffocate, but only the most humorless among them are able to take it seriously.
- Star Wars Legends: In Fate of the Jedi: Outcast, Luke Skywalker's teenage son Ben removes his oxygen mask on a planet with a lot of helium in the atmosphere (Plo Koon's homeworld in fact). He then goes on to sing a song to the annoyance of his father. A very sad song. Until you imagine it in a helium voice.
Where fields once grew, a road runs through, and buildings hide the sun,
Where grass of green could once be seen, are only gray and brown.
My childhood home, while I did roam, became a place of sadness.
Now I return, my heart does yearn for times of light and gladness.
- The title character of Stepsister From Planet Weird is from a shapeshifting alien race that lives off helium. When her Earthling stepsister walks in on her sucking the helium from a party balloon as a snack, the alien tries to explain herself and is surprised that her human form suddenly has a high, squeaky voice.
- One death in 1000 Ways to Die (#226, to be exact) involved a teenage couple breaking into a large helium-filled basketball due to this trope. By the time they realized they couldn't breathe, they were in no state to find the seam again. Presumably based on this 2006 Darwin Awards story.
- In an episode of The Adventures of Brisco County, Jr. Brisco and several of his companions board a blimp created by Professor Wickwire. The blimp uses helium, and the trope is invoked.
- The Big Bang Theory:
- In the episode "The Vengeance Formulation", when Sheldon appears on the National Public Radio talk show Science Friday, his enemy, Barry Kripke, fills his office with helium.
- In the episode "The Launch Acceleration", Leonard shows Penny how the sulfur hexafluoride he uses in his experiments causes deep voices.
- On Cheers, Norm and Cliff sing "Lollipop" this way at Rebecca's bridal shower until Frasier stops them. They then join in his rendition of "Isn't It Romantic" after inhaling helium again, whereupon Frasier pops one of their balloons in a rage.
- CSI: In "The Finger", a kidnapper inhales helium capsules to disguise their voice when making ransom demands.
- The Day Today uses the trope to particularly hilarious effect in a report on Sinn Fein. In a case of Art Imitates Life, The Day Today mastermind Chris Morris, as a junior in radio, released helium into The BBC's air vents just as the news was about to be broadcast.
- Doctor Who uses this for a non-comedic purpose in "The Robots of Death". After the villain controlling the robots orders them to kill the humans (except himself), the Doctor gets Leela to open a cylinder of helium so that robots won't recognize the villain's voice and kill him. The Doctor is unaffected by the helium, due to his Bizarre Alien Biology.
- On her talk show, Ellen DeGeneres decided to put deep-voiced American Idol winner Scotty McCreery to the test. The results, or lack thereof, were amusing.
- The Eureka episode "What Goes Around Comes Around" has a particle accelerator that's cooled by liquid helium. Naturally the cooling line breaks and everyone becomes squeaky for about half a scene until they can shut the line off.
Carter: Why are we talking like Chip N' Dale?
- In Farscape, Rygel will, if nervous or angry, fart helium. Anyone in close proximity to him will start speaking in a high-pitched voice.
- One episode of Friends has Chandler inhaling helium and singing "I Will Survive".
- On Genius, Dave Gorman and guest Neil Innes couldn't resist giving this a try when someone suggested Helium-filled bubble wrap.
- The Spanish Game Show El gran juego de la oca (The Great Game of the Goose) had this as one of the challenges. The contestant was blindfolded and had to guess the voices of the show's hosts and characters after they sucked helium from a machine.
- The Helium Chorale. Scottish comedy duo Hale and Pace slaughter Händel's "Hallelujah" chorus. Cue instant loss of dignity.
- An episode of Hannah Montana had Miley and Jackson throw a makeshift party for Robbie Ray and invite a few people, one of whom is the guy who blows up the balloons.
- One episode of Hell's Kitchen had Sabrina and Tek messing around with helium while blowing up balloons for a dinner party, even going so far as to imitate Ramsay.
- On the February 23, 1987 episode of Jeopardy!, an Audio Daily Double in the category of "Chemistry" saw host Alex Trebek inhale helium before delivering the clue "Type of gas I just inhaled that makes me talk like this."
- Kaamelott: After messing around in Merlin's laboratory, Perceval and Karadoc manage to make a potion that makes them sound like this. It also makes them invulnerable, but apparently they kept talking throughout an entire battle, because Lancelot snaps and tries to kill them.
- In one episode of Late Night with David Letterman where the theme of the night was audience voting, the audience voted to have Dave's and his guest's voices electronically modified to sound as if they had inhaled helium. Dave's guest (Jane Pauley) refused to talk after that.
- In My Name Is Earl:
Randy: [inhales balloon air; in helium speech] We represent the lollipop guild, the lollipop guild, the lollipop—
Darnell: Randy, those aren't helium balloons.
Randy:' [normal voice] Aw, too bad.
- MythBusters not only does this during experiments where helium is involved, but they've also used Sulphur Hexafluoride, a gas six times denser than air, to get the opposite effect, with a "Don't try this at home!" warning from Adam right before he starts inhaling the stuff ("And my voice gets really low, although somehow I'm still funny. It's scientific! HAHAHAHAHA!") Watch it here.
- Once on The Price Is Right, announcer Rich Fields inhaled helium before reading the prize copy as part of a Showcase skit. He then did it again for his signoff.
- One episode of the Canadian sketch show The Red Green Show opens with Red demonstrating how to cheat on a physical exam using helium to reduce your weight by inflating a swimming pool floaty with the helium and putting it in your pants. Needless to say, the plan backfires when the floaty explodes as soon as Red closes the door to his van. "Oh, the Humanity!" he exclaims in a helium voice.
- Scorpion: In "Dam Breakthrough", the team needs helium balloons. Toby inhales from a tank and starts singing "Grandma Got Run Over by a Reindeer". Cabe, looking incredibly serious, also inhales some and continues singing. Happy breathes some in and finishes the verse, culminating in a rare slight giggle from her.
- In a scene from Scrubs, J.D. talks about a nervous patient who accidentally inhaled air from a helium tank.
- In one episode of Special Unit 2 they found the Pied Piper of Hamlin (or at least one of his species) acting as a kid's show host and using his music to make the viewers commit crimes. The agency determined that they needed to alter his instrument so it dropped half an octave to break his control, then discovered that the instrument was fake and that the music was his own voice, so Nick shot a few nearby balloons while he was playing.
- Top Gear once tested how well the roofs of old convertibles had held up by putting the presenter in their vehicle with an open tank of helium. James and Jeremy's roofs were in good condition and held in the helium, resulting in them getting squeaky voices. Richard's heavily-modded convertible allowed the helium to leak and didn't change his voice at all, much to his disappointment.
- There was also an episode of Wheel of Fortune where, on a set decorated with balloons, neither Pat Sajak nor Vanna White could resist.
- Wayne Brady of Whose Line Is It Anyway? was known for pulling this off without actual helium.
- Parodied in Will & Grace, where Jack and Karen attempt this trope. Jack successfully pulls it off, but Karen's voice doesn't change, due to it already being high-pitched.
- Rayman uses this practically in the opening of Rayman Raving Rabbids 2. You'll see.
- Guybrush in Monkey Island 2: LeChuck's Revenge, shown through giving his dialogue lines a tiny font (the remake of the game has voice acting, so you get to hear it). Also used in The Curse of Monkey Island, which had voice acting as well.
- Helium is an important element of several puzzles in one of the Sam & Max games, since it lets Sam sing high notes. Badly.
- The Science Vessel in StarCraft has this as one of their Stop Poking Me! sounds:
I think we may have (shift) gas leak.
- In Conker's Bad Fur Day, if you use the first Context-Sensitive Button for a second time after Conker's hangover is healed, he'll pull out a helium canister, which Birdy will snatch and huff (as if he was drinking a beer, actually):
Really nice helium, heheheh.
- In The Simpsons Game one of Homer's powers is inflating himself in which he'll say random dialogue in helium speech. "I'm slightly lighter than air".
- In Guilty Gear Xrd, one of items Faust can throw at random is a bottle of helium that serves no purpose other then giving the one who touches it a comically high pitched voice for a lengthy period of time.
- Miis in Mario Kart have become (in)famous for the pitch of their voice. They dont actually inhale helium, though.
- In Crysis 2, Commander Lockhart's hammy exhortations to his men to kill you can be made even more comical via an easter egg that you can trigger to release helium into his room.
- In Kingdom Hearts III, an optional conversation in the Toy Box can be triggered by striking the valve of a helium tank or popping balloons, which causes everyone's voice to become high pitched. They all have some fun talking in their new helium-induced voices... Except Donald, who isn't affected at all.
- Used in the prologue of Ever17. Before visitors can enter the underwater theme park of LeMU, they must go through a compression chamber and adjust to the change in air pressure via helium. Earphones are given to each visitor to make everyone's voices sound normal, but when Takeshi removes them and talks to an already high-pitched Coco...
- Happy Tree Friends: Cuddles pulls this in "A to Zoo" with a helium tank for inflating balloons. Of course, it's Happy Tree Friends, so eventually he manages to impale and inflate his eyeball with it, which later traumatizes Flaky.
- Homestar Runner:
- Played with a bit in the appropriately named SBEmail. Strong Mad tries to do this, but it has no effect on him:
Strong Mad: [usual guttural half-shout] THIS IS MY FUNNY VOICE! [speaks louder for emphasis] THIS IS MY FUNNY VOICE!!!!
- However, we later find that sucking up bandwidth has this effect on Strong Mad. Don't ask.
- Played with a bit in the appropriately named SBEmail. Strong Mad tries to do this, but it has no effect on him:
- DSBT InsaniT: This is emulated with Balloon's voice.
- In the Bad Call TV episode "You Got the Flight Stuff, Baby," one man winds up with this voice after consuming enough Pepsi to gain the Seven Million Pepsi Points required for a Harrier Jump Jet that was (jokingly) mentioned in the commercial. Sadly, this is only partly fictional. No, one man didn't actually drink that much Pepsi, but he did manage to convince enough people to give him their Pepsi Points to try for the plane.
- A young couple earned a mention on the Darwin Awards web archive, having remained inside a large helium-filled (and oxygen-deficient) inflatable chamber, laughing about their own altered voices, long enough to pass out and die.
- Daniel Floyd of Extra Credits constantly narrates his videos with a voice that sounds like it's been computer-shifted into this.
- In the Musical Episode of Flander's Company, Armand Trueman breathes in a helium balloon so he can sing with a high-pitched voice.
- Happened unintentionally to Earthworm Jim in the animated series, with Peter Puppy being unable to stop laughing.
- Used in Clerks: The Animated Series; Silent Bob inhales helium and stands in silence for several seconds. Jay tells him in exasperation, "It's only funny if you talk, stupid."
- In an episode of Sealab 2021 in which a Predator was running around the place killing people, Dr. Quinn had the bright idea to mess around with the station's atmosphere in an attempt to hinder the alien aggressor. This ended up pumping a lot of helium into the air vents, which resulted in the crew laughing uproariously over how one of them sounded like a Chipmunk... who is then killed by the Predator, the crew laughing at his high-pitched screams of agony.
- A Family Guy cutaway shows Stewie doing helium at a birthday party:
Stewie: I'm a female! I have a high voice! I have reproductive organs inside of me, and I buy groceries!
- Another episode had Peter shooting a parade balloon of Brian after the latter becomes the new Pawtucket Patriot mascot, causing everyone on the ground to talk like this. Except for Jerome, who says he's impervious to it.
- Bob's Burgers has one episode at a party where Tina and Louise inhale helium. Bob then asks Tina for some, and sucks some in.
- The Simpsons's Sideshow Bob, while broadcasting his plan to destroy Springfield from inside the Duff blimp in "Sideshow Bob's Last Gleaming"; Lisa figured out where he was from the squeaky voice, and she and Bart head out for the Duff blimp. After Bob finishes his speech in his chipmunk voice, he says "Pesky helium! Shoo! Shoo!" and waves his hands, and his voice goes back to normal.
- This happens to Krumm in Aaahh!!! Real Monsters where he swallows a helium tank that not only causes his voice to be high-pitched, it even causes him to float in the air, being supported by a string to keep from floating away.
- In Home Movies episode "It Was Supposed to Be Funny," Brendon and Jason take balloons and candy over to Melissa's house, and after she says, "It'll take more than balloons and flowers for me to forgive you, Brendon Small," and upon her departure her dad says to the boys, "Could I have some of that candy?" the three male characters suck in helium on Melissa's dad's couch — the moment highlights that they're all very stuck in boyhood.
- Batman: The Brave and the Bold: Batman teams up with the Metal Men, a team of periodic element-themed robots, to fight the Gas Gang, a team of slightly-less periodic element-themed animated gas clouds (one of them's named Chloroform) in the episode "Clash of the Metal Men". Helium's only power is to give people Helium Speech. Luckily for him, he's the kind of guy who thinks that gag never gets old. Truthfully though, when used on Batman, it's hilarious.
- Robot Chicken depicts Alvin and the Chipmunks as having fairly deep voices until Dave floods the recording studio with helium in an attempt to asphyxiate them, but kills them in the process.
- In Phineas and Ferb, one of Dr. Doofenshmirtz's evil plans involved filling the entire tri-state area with "Doofelium" making his high squeaky voice lower in comparison, because making his own voice lower would be too much of a hassle. Ended up affecting himself and yelling out his catchphrase ("Curse you Perry the Platypus!") in helium speech.
- Happens once in Fanboy and Chum Chum when Boog's plastic bubble gets filled with helium, right as he's about to punch the titular characters. He notes that it's VERY hard to sound threating with his voice like that.
- Total Drama:
- The Looney Tunes short "Long Haired Hare". Bugs Bunny replaces an opera singer's throat spray with liquid alum; as he does warm-up exercises singing Figaro, each time he says it his head shrinks and his voice becomes higher-pitched.
- In the Screwy Squirrel cartoon "Lonesome Lenny" at one point Screwy sticks Lenny's head into a bucket of alum and he says while his head is shrinking "Why did you put my head in the bucket, George? You shouldn't have put my head in the bucket, George, why did you do it?" in a high pitched voice.
- In an episode of Rocket Power, Sam accidentally spreads the "Fiji Flu" to his friends, where one of the side effects is having a very high-pitched voice.
- In an episode of Class of 3000, helium is released into the cooling vents as a practical joke. Those affected included Sunny Bridges, Kam, Li'l D, and Principal Luna. Notably, it didn't affect Philly Phil, who thought his voice would sound weird.
- Falsetto Jones, the villain of the week on Kim Possible, has an extremely high-pitched voice due to a freak accident involving helium (hence his name).
- The Amazing World of Gumball: Alan the balloon, and all his family members, all have pitched up voices.
- An early Beavis and Butt-Head episode had the duo steal balloons from a vendor in order to get high from the helium, after they inhale it and comment how funny they sound they exclaim "Oh no, we're neutered!"
- Donald Duck: Trope Codifier and he could be the Trope Namer. The Other Wiki even has him as the Trope Namer!
- Averted with Plo Koon in Star Wars: The Clone Wars, who speaks in a low, deep voice, despite the fact that he breathes helium.
- The Looney Tunes Show: Daffy starts speaking like this in "Mr. Wiener" after he inhales a tank of helium to stretch his stomach to win a hot dog eating contest.
- Futurama: The Planet Express crew have to rescue "helium miners" from inside the Sun. Bender convinces them to sing Camptown Races.
Leela: Attention, helium miners! Can you hear me?
Miners: For God's sake, help us! We're in agonizing pain!
[Fry, Leela and Bender giggle]
- Inverted in The Smurfs episode "The Magic Egg", where Clumsy gets a deeper voice when he is turned into a giant.
- In South Park, there's the dwarf Dr. David Nelson in the Season 11 premiere "With Apologies to Jesse Jackson". Trey Parker inhaled helium to do his voice.
- Characters in Totally Spies! speak in a high-pitched voice when chibified, but only in the sixth season.
- In an episode of Jonny Quest: The Real Adventures, this briefly happened to Jonny and Hadji because helium is sometimes used in deep sea diving equipment to reduce the risk of the Bends. Hadji commented it makes them sound like cartoon characters.
- One episode of The Proud Family had Oscar and Felix trying to remove a mouse from the Proud house, culminating in them deciding to fumigate the place and then accidentally filling the tent with helium, causing the house to be uprooted and fly off with Suga Mama still inside. When they get the house back down offscreen, Suga Mama lambastes Oscar in a high-pitched voice.
- Tony Shalhoub used it in the Men in Black movies, for the bits when Jack Jeebs's head is growing back after being blown off by either Agent J or Agent K, but the rest of the time, he uses the same voice he uses on Monk.
- This trope often shows up in works set deep underwater, like the book Sphere. This is Truth in Television to some extent; the nitrogen in normal air becomes toxic at very high pressure, so deep divers breathe a gas mixture which has had some or all of the nitrogen replaced with helium. However, films in such settings often purposely ignore the effect when it should be present. Having live actors breathe helium for every line would be distracting to the audience, not to mention being somewhat dangerous and ridiculously expensive.
- A new trend around anime conventions: getting voice actors to say their characters' famous lines after inhaling helium. Hilarity Ensues, usually.
- Lilo & Stitch: Chris Sanders when providing the voice for Stitch.
- Inversion: sulfur hexafluoride.
- Subverted, then inverted progressively harder as you continue down the noble gases, as demonstrated here. By the time the guy gets to xenon, he sounds like Zordon.