Voices Are Mental

"Jade-in-Jackie's-body: Why are there two of me? Jackie-in-Jade's-body: Why is your voice coming out of my body?"

- Jackie Chan Adventures, "Sheep In, Sheep Out"

When characters swap bodies, get possessed, are cloned, or otherwise change form, there has to be some way to remind the folks at home which character is doing what. The solution? Base the voice off of the "mind" (when bodies are swapped/stolen) or make it relevant to the personality (in instances of cloning).

If the result of possession, it may be lampshaded with another character noticing that "You sound different...", but if so it will be shrugged off or explained away, and will generally otherwise be ignored. It will be noticed in body-swap cases only as the plot demands and most likely the audience is expected to believe that in-universe, the voices didn't switch over. Sometimes, however, the other characters will notice the change, and the swapped person will have to disguise their voice to sound like the person whose body they are inhabiting.

Very prevalent in animation, where its much easier to pull off since the animation comes after the voice dubbing and where trying to make the switch apparent through body language and mannerisms may not work as well. In film and live-action television, using a different voice to come out of someone's mouth requires redubbing and is less likely to appear unless the possessor is someone with a voice worth hearing, such as The Devil. In purely visual media like Web Comics, it's usually averted, but may be played with using the colors, fonts, and styles of the respective characters' Speech Bubbles if one or both characters normally use special dialog bubbles.

Of course, in a body switch one wouldn't expect the subjects to sound the same as their current body usually does anyway (slight differences in mouth shape, lung capacity and the vocal cords themselves would make differences when somebody new tried to control them without practice), but nor should they sound like their real bodies as this completely ignores the physical aspect of speech. The way your voice sounds depends on the shape of your vocal chords and the shape of your mouth. No amount of brain swapping is going to change that.

Voices Are Mental is the "sound" aspect of Morphic Resonance. See also Eyes Are Mental.

Anime & Manga

 * Variation in Fullmetal Alchemist; Al sounds the same when his soul becomes affixed to a suit of armor, even though he doesn't even have a body anymore.
 * Played somewhat straight in the movie, where.
 * In the second anime, 's voice sounds different depending on who's in control at the time (which is probably based on how the manga indicated it with which side of his face his hair covered).
 * Late in the second anime, takes a much younger form, but his voice remains the same.
 * Alphonse's voice in the second anime is actually playing this much straighter when you take into account the revelation that yet his voice remained the same.
 * In Episode 148 of Inuyasha, we briefly witness an interesting variation: When Naraku takes Kikyo's form to make the protagonist think she betrayed him, his voice sure sounds like Kikyo's, but his internal monologue still sounds like himself, which leaves one weirdly surreal impression considering that you hear a deep male voice comming from a frail-looking girl. Something similar can be seen in a flashback when he transforms into a pretty girl to fool one of the protagonist's grandfather but stops bothering to disguise his voice when he finally confronts him and curses his family. This is averted both in thought and speech when he takes the form of a young nobleman, but this can be traced to Naraku's decision to permanently keep that appearance, and by extension, the voice, presumably because he liked them.
 * Originally averted in Cardcaptor Sakura's Freaky Friday Flip, but then played straight in the dub. Kero and Shaoran Li's voices remain the same, but their speech patterns and mannerisms are noticeably swapped.
 * Girls Bravo's Pool Episode not only had mental voices, but mental allergies.
 * The mental allergies were justified in that.
 * This was averted by, of all things, a Hentai OVA, fittingly called Body Transfer. Plausibly enough the voices of Internal Monologues remain the same from one body to another.
 * Happens in Pokémon Ranger and The Temple of The Sea, when the three members of Team Rocket swap bodies thanks to Manaphy's Heart Swap attack.
 * Happens in Slayers Evolution-R:.
 * The Japanese version of Digimon Tamers gave the Biomerged Digimon unique voices, However, the American dub blended the voices of the two partners. Because the identities of those involved are well established, this doubles as Viewers Are Goldfish.
 * Dragonball Z: Used repeatedly with Captain Ginyu, who can switch bodies with people. First he switches bodies and voices with Goku; then with a frog (it actually said "ribbit" in Ginyu's voice), and finally with Bulma. Nobody seems to notice this big drill sergeant voice coming out of normally-sized woman. Making this even weirder is the fact that he needed to say the attack's name for it to work, and a frog being unable to talk is exactly why he was stuck that way.
 * The voice difference was only to distinguish him from Goku, as to the characters, the voice that came out of Goku's mouth was Goku's own. Maybe they thought we wouldn't be able to tell or something?
 * In Darker Than Black, Intellectual Animal Mao is actually a Contractor with the ability to possess animals. He switches bodies a couple of times, so we get to see that he sounds exactly the same as a cat, a bird, or - all of which sound like his original voice, as seen in a flashback.
 * Subverted in Bleach, where unlike the example with Mao above, Yoruichi's voice in human form and animal form differs Hilarity Ensues once other characters (and the audience) figure this out.
 * One Omake in which Rukia and Renji swap gigai plays this completely straight.
 * Used in the second bonus OVA of Daphne in the Brilliant Blue when Maia and Gloria are switched. The switch in voices is brought up, but treated in such a way as though the other characters fully expect it to come with the territory.
 * Played with in Kämpfer,  and vice versa. Along with Unusual Ears and a tail this creates a Paper-Thin Disguise.
 * In Naruto except the female one have the voice of the first one we saw, even though that's not the same voice as the one controlling them.
 * Averted with Ino; when she uses her Mind-Body Transfer jutsu, she always speaks with her host's voice.
 * In original Japanese dub of Murder Princess Alita and Falis switch voices when they switch bodies. However, this trope was purposely averted in the English dub.
 * Subverted very creepily in Black Lagoon with
 * Inverted in the Japanese and Latin American versions of Detective Conan. "Conan's" young voice isn't just used when he's talking but also most of the time when he is thinking. In the dub he thought in the older voice.
 * Tony Tony Chopper from One Piece can take the form of a giant reindeer-man, but has the same little kid voice. The 4Kids! dub averted this, but it's generally agreed that the voice used for his large form sounded horrible.
 * Happens in RahXephon:
 * Taken to another level in Yu-Gi-Oh!, with mental voices as well. Yami and Yugi normally have different voices, but this also applies when they're thinking; if the two Mind Meld, then their Inner Monologues have Yugi's voice. If it's only Yami, then it's his own voice.
 * In the first OVA for the To Love Ru first anime, Rito is turned into a girl, but has the same voice. Averted in the second anime, as "Riko" instead has a female voice (but the same voice actor) for speaking while his Inner Monologue remain in his male voice.
 * The ghost Amanojaku manages to retain his original voice in Ghost Stories even after possessing Kaya, a cat, despite the fact that cats don't even have a vocal tract capable of producing language, and Kaya appeared to be nothing but an ordinary cat before the possession.

Fan Works

 * Inverted in a Freaky Friday Flip fanfiction of X-Men: Evolution in which each body uses the right voices for each body -- even the accents. So using the body of someone German automatically gives one a German accent.
 * Impressively averted in Dragon Ball Abridged when Goku and Ginyu switch bodies but are stuck with each other's voices and talk like themselves.

Films -- Live Action

 * Inverted in Face/Off. The swapped guys have the voices of the actors who play them- but not before and after...
 * Happens on and off in the Harry Potter films, via the Polyjuice Potion, though its averted in the books and is most likely for the audience's benefit since in Harry Potter, Draco never catches on to Harry & Ron as Crabbe and Goyle, and in Deathly Hallows, when the potion is used, a disguised Ron briefly spoke in the voice of the person he was impersonating until he realized he was talking to Harry. In the fourth film, this is definitely confirmed when is definitely not voiced by, because this wasn't revealed until after.
 * Happens in The Movie of Scooby Doo when the cast's souls were trying to find their original bodies.
 * Happens at the end of X-Men: The Last Stand
 * In the 2006 movie Its a Boy Girl Thing, voices stay with the bodies, but the thoughts of the characters are given as voiceovers in the possessors' voice.
 * Day Watch has Anton and Olga switch bodies in order to avoid Anton being dragged in by the Day Watch for a suspected murder. The voices carry over with the personality, and they each have to perform a small glamour in order to sound like who they look like.
 * The Ur Example may be Universal's The Ghost of Frankenstein (1942), in which the monster takes on the voice of Ygor (Bela Lugosi) after a brain transplant.

Literature

 * An inversion of this concept appears in Animorphs, where characters communicating mentally will pause frequently if they are out of breath, as if panting between words. Presumably this is simply because we're used to pausing if attempting to speak when out of breath, and the characters never trained themselves out of the habit for thought-speak.

Live Action TV

 * The Farscape episode "Out of Their Minds" begins with this, just so the viewers get what's going on immediately, by blending the voices of the two people involved. Later in the episode, though, the characters have all reverted to the body's voice, with each actor just using the other's body language and vocal patterns (or trying to).
 * Gilligans Island episode "The Friendly Physician". Mad Scientist Dr. Boris Balinkoff takes the castaways to his own island for mind-switching experiments. Each castaway speaks with the voice of whichever character's mind is inhabiting it.
 * And by the end, a cat and dog are speaking with the voices of the scientist and his mook.
 * In the first episode of Now and Again, John Goodman's character is heard "speaking" to Dennis Haysbert who informs him that he's just a brain hooked up to a computer now. Still sounds like Goodman. However, this may just be the character's mental reconstruction of his own voice; when he wakes up in his new body, we still see him as John Goodman until he takes a look in the mirror, at which point he becomes played and voiced by Eric Close for the remainder of the series.
 * In the Red Dwarf episode "Bodyswap", Rimmer and Lister switch bodies and their voices also switch.
 * If memory serves, there's a special feature on the DVD to watch it without the dubbed voices. They actually did a pretty good job of capturing each other's speech patterns. A missed opportunity to avert this trope, really.
 * Especially given that Chris Barrie (Rimmer) did voices for Spitting Image.
 * And earlier, when Lister has the mind of Executive Officer Carol Brown put into him so he can stop an auto-destruct sequence, he speaks with her voice.
 * In the Star Trek: The Original Series episode "Return to Tomorrow", several Enterprise personnel were (voluntarily) possessed by alien mental entities. When speaking, their voices were very different (louder and a different pitch, like in an echo chamber).
 * The trope is averted in the actual bodyswap episode "Turnabout Intruder".
 * In "Spock's Brain", the disembodied organ of the title manages to speak through the computer system it's plugged into. For some reason, it talks in Spock's voice without having his vocal cords. And this is actually not the biggest logic failure in the episode.
 * In the Super Mario Bros Super Show, Mario gets his mind swapped with that of Frank N. Stein's monster. It's not exactly the best dub job out there, but they did follow the trope. A knock on the noggin with a hammer for each of them is enough to swap them back.
 * In the Dollhouse episode "A Love Supreme",.
 * The trope is averted when Victor is imprinted with Topher's personality, though the viewer might think it was followed: Victor's actor Enver Gjokaj manages an uncannily good impersonation of Topher's voice.
 * This is actually playing the trope straight - the person swapped (or in this case imprinted) into a different body sounds exactly the same as they normally do. The show's creators just accomplished this in an unusual way.
 * Actually, this is exactly what it should be. The body (that is, the actor) tries to talk like the soul (the character). Since Enver Gjokaj is a freaking genius we don't really notice it, but there is slight differences.
 * Subverted in the Mork and Mindy episode "Metamorphosis-The TV Show" where Mork and Mearth switch bodies. They talk in each other's voices but in this case there are no dubovers involved - instead Robin Williams and Jonathan Winters expertly imitate one another.
 * In an episode of Warehouse 13, Pete and Myka switched bodies (thanks to an artifact), but their voices remained the same. To emphasis the switch, the actors (rather impressively) mimicked the other character's mannerisms.
 * El Chapulin Colorado redubbed For the Lulz when swapping the High-Toned Damsel in Distress and the baritone Big Guy. And when everyone got better they did it again with one scientific and the Right Hand Dog.
 * In Stargate SG-1, this trope was averted in the body-swapping episode. The various actors did a hilariously good job of adopting each others' mannerisms, so it was still obvious who was in whose body.
 * Averted in an episode of The Avengers when two enemy agents switch bodies with Steed and Mrs. Peel. Sort of unavoidable, since the bad guys were supposed to be infiltrating British intellence.

Video Games

 * Used in Kingdom Hearts, when Ansem possesses Riku. First he speaks with both voices at once, then eventually only Ansem's.
 * Then in the sequel, Riku has taken on Ansem's form. He has Ansem's voice till Sora discovers who he is, then suddenly he has David Gallagher's voice! It was a little bit unnerving, and it was also probably just symbolic.
 * Players of the original might not even notice the symbolism because Ansem/ suddenly changed voice actors between games, making an already confusing situation even stranger.
 * Let's just say Kingdom Hearts loves this trope.
 * But the most effective use of this trope is with  while retaining her original voice makes effective for Nightmare Fuel.
 * Another interesting version of this trope is used in Birth By Sleep
 * Then, there's Vanitas, who's  He shares   voice actor in both versions, although it isn't noticeable at first, because they just do a that darn good job at sounding evil. Once you figure it out, however, it leads to a lot of Fridge Brilliance.
 * Played with to a certain extent in the Metal Gear Solid series. In Metal Gear Solid 2, when Liquid possessed Ocelot, he'd speak with Liquid's voice. In the fourth game "Liquid Ocelot" always speaks with Ocelot's voice in the English version, and Liquid's voice in the Japanese version due to the unfortunate death of KÃ´ji Totani.
 * Averted and played straight in Nicktoons: Globs of Doom whenever Big Bad Globulous Maximus speaks through SpongeBob SquarePants. First, it's merely SpongeBob acting evil; the second time, we start with evil SpongeBob who switches to Globulous' voice mid-sentence (which is the cue needed for Jimmy Neutron to note that he's speaking through him and for Invader Zim to complain about Globulous being a larger ham than him. Yep.) and after that, it's pretty much a hammy Dee Bradley Baker "voicing" the yellow guy.
 * Averted in the video game adaptation of JoJo's Bizarre Adventure part five. Near the end of the game, everyone switches bodies, but they retain the voice of the bodies owner. Their Stands swap with them, though.
 * In response to the ninth Pokémon movie example above, strangely averted in Super Smash Bros. Brawl with Manaphy's Heart Swap attack when it comes out of a Poke Ball. Of course, making Zelda sound like Donkey Kong and vice versa would be a little weird, in retrospect.
 * When Momohime is being controlled by Jinkuro in Muramasa: The Demon Blade she still uses her own voice actor, but at a noticeably lower register. She also switches pronoun use to a pronoun commonly used by old men.
 * Remember 11 goes back and forth on this. When Kokoro and Satoru switch bodies, they retain the same voice actors (ie. Kokoro in Satoru's body still has Kokoro's voice), but the fact that people have trouble telling them apart, as well as things such as recordings made by Satoru-in-Kokoro's-body having Kokoro's voice, imply that their voices do stay with the bodies in-universe, but the player hears them with the associated mind for convenience.
 * Both applied and averted in season 3 of Telltale's Sam and Max series, The Devil's Playhouse. In episode 3, They Stole Max's Brain!, However, in episode 5, The City That Dares Not Sleep,
 * Also in Season 2, when Sam and Max swap bodies. Then there is the Monster, which can hold 2 souls simultaneously, switching between voices as (t)he(y) talk(s). And let's not forget about the demons, who emulate the possessed's voice - but sometimes fail.
 * In Disgaea 2: Cursed Memories, any character that gets transformed into a monster by the Dark Sun retains their original voice.
 * It's hard to tell whether this applies to Prototype, since we don't know exactly how the main character's shapeshifting works. He can mimic other people's voices in cutscenes, but in gameplay, he always makes the same grunts regardless of who he's impersonating. (From a Doylist perspective, the explanation is that they didn't bother to program alternate grunts for him; a Watsonian one could be that Alex himself doesn't bother messing around with his vocal cords for every single form he ever takes.)
 * It's hard to tell whether this applies to Prototype, since we don't know exactly how the main character's shapeshifting works. He can mimic other people's voices in cutscenes, but in gameplay, he always makes the same grunts regardless of who he's impersonating. (From a Doylist perspective, the explanation is that they didn't bother to program alternate grunts for him; a Watsonian one could be that Alex himself doesn't bother messing around with his vocal cords for every single form he ever takes.)

Web Comics

 * In Gunnerkrigg Court, Speech Bubbles are colored differently to distinguish the different characters' voices. And Reynardine's bubbles are the same color regardless of whose body he's possessing. Word of God clarifies that his voice is always recognizably his own, but he doesn't sound exactly the same in different bodies.
 * Which is reasonable. Different people have different ways of speaking with their Verbal Tics and accents. Plus, vocal chords are different for every person and species of animal. It still doesn't explain how he can make a stuffed wolf toy talk, though.
 * Might it perhaps involve magic?
 * Also suggested in Looking for Group when Richard is summoned back from the Plane Of Suck and ends up in Pella's body. Richard's trademark speech bubble is there, clearly indicating who is supposed to be the one doing the speaking. This is also used when Richard takes over a stone golem.
 * Of course, given that Richard is a lich of some sort, this might be justified in that he's using magic.

Web Original

 * Red vs. Blue plays with this trope a few ways. The first time Church possess someone (Sarge) he speaks as Church pretending to be Sarge, later when possessing Donut, he speaks in his normal voice, who Tucker and Caboose hear as Church and Grif and Simmons hear it as Donut. Later, when Church possess Lopez, he speaks in his normal voice in a different language, apparently because Lopez is physically unable to speak English, Grif and Simmons still dont notice a change however.
 * The reason behind the first change is because the writers couldn't decide if Burnie (Church's VA) would pretend to be the character he was possessing or if they would have the possessed character's VA do thier voice different or try to sound like Church. Ultimately Burnie decided that because his Donut impression sounded too much like another character, that they would do away with it and just have Church's voice.
 * Another curious example, Church's second robot body is seen only speaking French, yet Church speaks English in his normal voice when inhabiting it, inverting the Lopez example.

Western Animation
"Luthor (In Flash's Body): If nothing else, I can at least learn the Flash's secret identity. (removes mask, Beat) I have no idea who this is."
 * Given that Freaky Friday Flip is one of many stock Plots in Western animation, it might be easier to list the shows that avert or avoid this trope.
 * Played straight and averted in The Adventures of Jimmy Neutron. When Jimmy and Cindy switches bodies, the "brains" retains their voices, but when Jimmy creates imperfect clones of himself, each has a different voice related to their personalities.
 * Danny Phantom has this happen whenever someone is possessed, leading at least twice to one character arguing with themselves with two distinct voices.
 * Like the temporary eye colour change of possessed people, it is somewhat confusing as to whether this is actually happening in the DP world or merely a cue to help the audience follow what's going on. The other characters never notice it, at any rate.
 * Happens in the pilot of Dexters Laboratory, where Dexter and Dee-Dee end up in each others' bodies at the episode's conclusion.
 * The DuckTales episode where the Beagle Boys impersonate Huey, Dewey and Louie, thanks to Magica DeSpell's magic.
 * Happens in Lilo and Stitch: The Series, where the title characters swaps bodies in one episode.
 * Happens in Captain N the Game Master.
 * Happens in Darkwing Duck.
 * The Tick vs. Science had a lot of fun with this, with human characters suddenly saddled with the vocalizations of a giant sentient tongue and so forth.
 * Teen Titans played this straight in "Switched"
 * A fun story from one of the writers: the voice actresses for Raven and Starfire were originally supposed to switch roles, with "Starfire" speaking in monotone and "Raven" speaking cheerfully. It then turned out that both actresses were so good at mimicking the other character's voice that they could barely tell a switch had been made, leading the writers to simply drop the idea.
 * An aversion (in a sense) from the same show comes in the form of Jericho, a Heroic Mime who only seems to be able to speak when he's possessing someone who can speak. As he has no voice of his own, it can be assumed that he uses their voice to speak (though this would be a more definite assertion if the only time the viewer was shown this wasn't when he was possessing Cinderblock...)
 * A brief aversion in the Larry episode "Fractured" - reality was broken, mouths were traded around, so characters talked with other voices. Particularly charming, Cyborg talking smack via Starfire's voice.
 * The Jackie Chan Adventures episode "Sheep In, Sheep Out" provides the quote at the beginning of this page.
 * Although they averted this trope in the episode with the Chinese Vampire. Through a series of "Chi transfusions" Tohru acquires Jade's mannerisms and Jade acquires Uncle's, while everyone's voice actors stay the same.
 * At first averted, then played straight in the Ben 10 episode "A Change of Face".
 * Again played straight in "Ghostfreaked Out" whenever Ghostfreak possesses someone. (Also, their eyes change.)
 * Later averted in Ben 10 Alien Force, when an alien is turned into a clone of Ben that's just has much more serious and stilted inflection. Of course, this was probably so it would be hard for the audience to figure out before The Reveal, and because the guy was apparently an alien like Greymatter before it would have sounded even more ridiculous than usual.
 * The largest aversion is that Ben's alien forms are voiced by several different voice actors, all of them different from Ben's normal voice actor but Upgrade (who seems to be synthesizing his voice). In contrast, Ben's Evil Counterpart Kevin 11 retained the same voice in all his forms when he was shapeshifting into several of Ben's different alien forms.
 * Played straight in an episode of Ultimate Alien where Kevin and Gwen are each turned into several of Ben's alien forms, all of which were their voice actors impersonating the voices those aliens normally had (including Gwen's VA impersonating Rath).
 * Averted in the Justice League Unlimited episode "The Great Brain Robbery", when Lex Luthor and Flash exchange bodies. They use the voices belonging to the bodies. The writing staff wrote the ep solely as an Actor Allusion for Smallville fans, since live action Lex and animated Flash are both played by Michael Rosenbaum. A significant portion of the episode's comedy also comes from the usually sinister vocal stylings of Lex's voice actor, Clancy "The Kurgan" Brown, playing the goofball Flash for an episode. Among the jokes that saved the episode:

"("Lex" tries to leave the men's room) Dr. Polaris:Aren't you going to wash your hands? Lex:No, because I'm evil."
 * It gets better, as Lex's regular voice actor performs a hilarious Flash in Lex's body trying very hard to sound evil but coming off as Poke the Poodle instead.


 * Also averted in the episode "Dead Reckoning", where characters don't change voices when possessed by Deadman. They do, however, gain his accent and mannerisms.
 * In The Powerpuff Girls, when the girls were Freaky Friday Flipped with the Professor, the Mayor, and Miss Bellum, they not only retained their voiced but their powers, too. Granted, it was mainly because as the Professor's Techno Babble explained, they switched outer "layers" rather than their entire bodies being swapped.
 * Code Lyoko plays this straight. In "A Fine Mess", when a computer glitch in Lyoko switches Odd's and Yumi's bodies, they also switch voices. The same in episode "Nobody in Particular", where a disincarnated Ulrich still retain his own voice while possessing Jim -- or Kiwi, actually talking through the dog.
 * That last part is actually quite ironic since Ulrich and Kiwi have the same voice actress.
 * Notably averted in Gargoyles; Coldstone has three different personalities, all of which use Coldstone's voice with minor inflections when they're in control of the body. The female personality, the first time she controlled the body, even said "My voice. It's different!" In a later episode, Puck switches the minds of various members of the cast (including all three of Coldstone's alternate personalities) and everyone's voice matches the body, rather than the mind, of the speaker.
 * This is worked into the plots of said episodes, as it allows them to conceal which personality is in control of a body until The Reveal.
 * Between those two it was sort of used, sort of averted when Wolf was possessed by the Viking Hakon, his ancestor. Both characters are voiced by Clancy Brown, and the ep was written to highlight his ability to talk to himself in the voice of either character, making possessed Wolf sound subtlely different from Wolf.
 * Averted similarly in Transformers Animated with Blitzwing, who also has three personalities and, bizarrely, associated faces; they use the same voice and accent (mostly, since Hothead actually has an Austrian rather than German accent), but have remarkably different inflection.
 * Averted again, later in "Where Is Thy Sting?":.
 * Speaking of Transformers, played straight in the Beast Wars episode "Possession" where Waspinator is possessed by Starscream's spark; he consequently sounds like a G1 Starscream soundalike.
 * Both averted and subverted in the original G1 series. Starscream's ghost possessed Cyclonus, and could do both his voice and Cyclonus' voice. When he cried out in surprise, however, his troops noticed that he sounded like Starscream.
 * Also averted in the Freaky Friday Flip episode of Pirates of Dark Water. Probably for the sake of hearing the monkey-bird's voice do Hulk Speak.
 * Partly averted in Tale Spin. Baloo and Kit switch bodies but don't switch voices. Instead, the voices stay with the bodies, but Kit's voice is pitchshifted down and Baloo's is pitchshifted up.
 * Notably, it's shown that it's not just a case of Rule of Perception but something other characters can notice, as they had to trick Rebecca into thinking there was something wrong with her hearing.
 * Subverted in an I Am Weasel short. Owing to a surgical mishap, Weasel and Baboon's brains are switched. Michael Dorn (Weasel-in-Baboon) imitates Charlie Adler's goofy way of speaking, while Adler (Weasel-in-Baboon) speaks with Dorn's dry precision. The effect is pretty hilarious.
 * Kim Possible did it with two different brain swaps in the Freaky Friday Flip episode. In both cases, Shego thinks it's just a hoot.
 * Lampshaded but handwaved by Kim, who explains away her regular voice as "puberty".
 * American Dragon Jake Long had a Freaky Friday Flip with his little sister, with this trope hard at work.
 * Averted in a Freaky Friday Flip episode of the 1980s version of Teenage Mutant Ninja Turtles. Splinter and Shredder were swapped, but the voices stayed with the bodies.
 * Played straight and averted with Deadman in Batman the Brave And The Bold: when he possesses Batman Deadman's VA speaks, but when he possesses Speedy, the same VA just imitates Deadman's New York accent. Later, when Batman and Batwoman go through a Freaky Friday Flip, they keep their voice actors, who imitate each others' acting (albeit Bader is acting much more effeminate than Batwoman ever really did).
 * In Batman Beyond, this trope serves as the Reveal that
 * It's a bit odd given that the body's real voice is also accessible.
 * Perhaps he practiced so as not to creep himself too much.
 * The Real Ghostbusters had Egon and Slimer switch minds and voices. On top of that, Egon's vision problems apparently transferred over with his mind, because Egon (in Slimer's body) insists on wearing his glasses.
 * Averted in an episode of Two Stupid Dogs: the dogs switch minds, but they still have the same voices. It's their mannerisms and the way they talked that switched.
 * Happens in a Family Guy episode, where Peter and Lois accidentally switch bodies, when they try one of Stewie's inventions.
 * Averted in a Lloyd in Space episode where Lloyd and Francine switched minds. The voices stayed with their respective bodies and only their personalities and mannerisms switched. Possibly done because Lloyd's genius friend Douglas would have noticed the obvious change in voice.
 * Used in the Jimmy Two-Shoes episode "Monster Mutt". Especially weird since one of the subjects was an animal.
 * Ditto in The Fairly Odd Parents episode "Presto-Change-O", though you could just say it was due to the magical way they switched bodies.
 * An early episode where Timmy changed bodies with Vicky's dog averted this: when in Timmy's body Doydle sounded like Timmy and when in Doydle's body Timmy could only bark/"speak dog" and there's what's obviously a voiceover to let us know what he's really trying to say.
 * Shown in the Futurama episode "The Prisoner Of Benda", where virtually the entire cast, plus a washbucket and an Emperor, switch bodies but retain their voices. It's necessary, though, since the sheer amount of body-swapping would confuse anyone if they didn't keep their original voices. Additionally, it may be for the audience's benefit, since the characters still need to tell each other who's who.
 * Considering at least 3 of the chars switching are played by Billy West...
 * Men in Black once had Kay turned into a baby but retain the same voice. This wasn't just for the audience, he sounds the same to all the characters, which Frank finds weird.
 * Another episode takes this trope to its logical conclusion when Zed's brain is removed, and the disembodied brain talks with Zed's voice.
 * "Does This Duckbill Make Me Look Fat?" was a switch-a-roo episode on Phineas and Ferb where Candace and Perry switch body, cue Candace being able to talk and sound like herself in Perry's body and Perry chattering while in Candace's.
 * Averted in the sound recording of the Invader Zim episode Ten Minutes to Doom. Which is to say, when Dib gets "possessed" by Zim he still sounds like Dib. Just... more evil.
 * Averted in the '90s Mega Man cartoon, when Mega Man and Snake Man were switched, but Mega Man even spoke Sssssnaketalk (Snake Man's Verbal Tic) rather than just getting his voice. Snake Man might have been chosen for the plot since he and Mega Man shared the same voice actor, though.
 * Subverted in The Real Adventures of Jonny Quest: Jeremiah Surd performs a "neural cyber-transfer" with Race Bannon. At first he talks in Surd's voice but then when he explains how he plans to sneak up on and kill Dr. Quest, he clears his throat, then finishes his sentence in the voice of Race Bannon, hammering home how perfect his possession of Race's body is. Race-in-Surd's body talks like Race but with a noticeable electronic echo, representing the breathing apparatus Surd's crippled body uses.
 * Superman: The Animated Series: When the Parasite absorbs Earl Garver's personality, Garver takes control of the Parasite's body and talks in his own voice. Makes sense since the Parasite already demonstrated the ability to copy the voice of a person whose energy he drains.

Real Life

 * Larynx transplants have been possible since 1998, and, in at least one case, the recipient sounded like he did before his own larynx was crushed, rather than sounding like the donor. So voices are partly mental.
 * The larynx actually has very little to do with how voices sound, but it's not much mental, either. The larynx is a bit like the mouthpiece of a brass instrument. All mouthpieces sound about the same alone, but the sound quality changes drastically depending on whether its attached to a trumpet or tuba. In this case, the entire human head acts as the actual "instrument."
 * Of course, any accent or Verbal Tic would not be removed if switching bodies was somehow made possible.
 * For the mind or the body?