- Can you name this artist?

(catchy hip-hop music) Sounds like Jay-Z covering Nicki Minaj's "Chun-Li", right?

Or is Nicki Minaj just Jay-Z sped up?

This conspiracy has been floating around for years and it's hilarious.

(catchy hip-hop music) - What you're actually hearing is the effect of pitch shifting, the result of warping notes, voices, and other sounds to make them sound much lower or higher than normal.

It's a common tool found in guitar solos and hip-hop samples, even cartoons.

But how does it work and why do people use it?

(dreamy pop music) We're here with Dianna from Physics Girl.

(high pitch sound) (glass breaks) (gasping) - My head is not (screaming) - [Nahre] We were talking earlier about what musicians think of pitches, as is basically like-- - A high note is a high pitch, low note is low pitch.

So in science, we talk about those notes as low and high notes, as frequencies.

So check this out.

If I sort of slide up, I'm not a great whistler, but if I start to slide up the scale, like from low pitch to high pitch.

(high-pitch frequency) What did you notice?

- The recording just-- - Yeah!

- They shrink, come closer.

- They got closer together.

So using a wavelength, which is related to what we call frequency, shorter wavelength is higher frequency.

It just happens more often.

- Is that what's happening when we're pitch shifting?

We're just taking that and scrunching the wavelengths?

- Yes, you would be just taking your wave form and squeezing it, making those peaks closer together.

Or further apart if you pitch shift down.

- Before you hear our original song, let's talk about how other artists have used pitch shifting in their music.

("Chun-Li" by Nicki Minaj) - When we made Nicki Minaj sound like Jay-Z, we slowed down the song to 130%, which stretched out the waves to lower the pitch.

Many artists have used speed-altering techniques to manipulate pitch in their songs, but the band that really pioneered this style is one I'm sure you know.

("Bad Day" by Alvin and the Chipmunks) Songwriter, Ross Bagdasarian, was experimenting with the tape recorder in the late 1950s and discovered a sound that would define his career.

He used this technique to create a duet with himself in his hit song, "Witch Doctor" from 1958.

("Witch Doctor" by Ross Bagdasarian Sr.) Then one day while driving in Yosemite National Park, a chipmunk dashed in front of his car and well it all clicked.

(popping sounds) He recorded the vocals for Alvin and the Chipmunk at half the normal speed and played the tape back at full speed to create the effect.

Here's how they sound when you slow a chipmunk song back down to it's original speed.

(slow a cappella music) ♪ Where is the moment we needed the most ?

♪ This technique wasn't new.

For example, it was used in 1939 to give the Munchkins of the Wizard of Oz their unique sound.

- Follow the yellow brick road.

- Follow the yellow brick road.

- It was also used for cartoon characters like Tweety Bird.

- I thought I saw a pretty cat.

- Pitch shifting wasn't only used for cartoons and magical kingdoms, Chuck Berry didn't want to sound like a chipmunk, but his record label did speed up his recording of "Sweet Little Sixteen" just a little bit, so that he sounded younger.

("Sweet Little Sixteen" by Chuck Berry) When creating The Beatles's "Strawberry Fields Forever," John Lennon wanted to use parts of take seven and 26, but due to so much experimentation in the studio, the two parts were recorded at different tempos and in different keys.

Producer George Martin slowed one tape down so that the two matched.

You can actually hear where the splice happens.

Listen to the shift right before John Lennon says, "Going to."

("Strawberry Fields Forever" by The Beatles) You might've noticed John Lennon's vocal tape was slowed down, which is why it sounds dreamier, almost slurred.

In more recent years, producers like Kanye and Just Blaze took notes from Ross Bagdasarian and sped up soul and R&B samples, adding a new Alvin and the Chipmunks kind of flavor to their beats.

("Through the Wire" by Kanye West) - There's another way to affect pitch without adjusting the timing at all.

Artists like Jimi Hendrix use guitar pedals to digitally affect the pitch in real time.

In his song "Purple Haze", he played the guitar through a pedal called the Octavia, which electronically doubles the frequency of the notes that are being played, so that they sound an octave higher.

(high-pitch guitar riff) In more recent years, Jack White used the guitar pedal called the Digitech Whammy to do the exact opposite.

Because The White Stripes lacked a bass guitarist, Jack White pitched down his guitar to sound like a bass in the song "Seven Nation Army".

(bass guitar riff) Artist have also used pitch shifting to fix mistakes.

Auto-Tune was invented in 1997 to hide studio errors.

Notes that were sung a bit off were no longer going through a take.

Producers were able to shift frequencies of notes to make everything sound perfectly in tune.

- But then on October 19th, 1998, this happened.

("Believe" by Cher) Auto-Tune evolved from the audio version of white out into an instrument itself.

Cher didn't use it to cover up her mistakes.

Instead, she used it as a vocal effect.

Some purist still deride it as a crutch or a gimmick, while others like Radiohead, Lil' Wayne, and T-Paine saw it as another tool to make something unique.

- When singer, Casey Dienel, claimed that Justin Bieber and Skrillex's song "Sorry" infringed on the copyright of her song "Ring The Bell," Skrillex took to Twitter to show that he didn't steal the song, but actually used pitch shifting to create the song's chorus in a way that made it a very close match.

- [Skrillex] Now take this ♪ Ooooooh ♪ Pitch it up 12.

See my talents.

♪ Ooooooh ♪ - In recent years, there has been a wave of choruses that feature vocals with raised pitches and fragmented parts with producers contorting the human voice into catchy but alien-sounding hooks.

Think Major Lazer's "Lean On" (catchy pop music) or Skrillex, Diplo, and Bieber's "Where Are U Now."

(catchy pop music) - What do you think we can do with the pitch shift song?

- Maybe taking a sample of someone talking, because there are pitches that if you really examine it.

- Yeah.

- What if every element of the song is pitch shifted in song way?

- I feel like it's gonna sound really trippy because everything, every part of, there's nothing familiar in there anymore because everything has been altered.

- Trippy is good and is instant.

Trippy is great.

(laughing) - I hope it sounds trippy.

- I have the clip of Dianna speaking right now.

- Push it.

- Let me play it.

- [Dianna] I'm Dianna from Physics Girl and you're watching Sound Field.

- We should use her definition of pitch.

We can start the track just to give the clips of context but then gradually pitch shift it.

- Alright, so.

- [Dianna] Pitch is the frequency of the sound wave, which tells you how often your wave is moving back and forth.

Your wave is moving back and forth.

- Your wave is moving back and forth, back and forth.

(laughing) - Back and forth, back and forth, b-back and forth.

Back and forth.

Back and forth.

(table hitting) - Okay.

- We have our track.

(laughs) (electric synth music) - [Dianna] Pitch is the frequency of the sound wave, which tells you how often your wave is moving back and forth.

Wave is moving back and forth.

(electric synth music) - As for Jay-Z and Nicki Minaj, well Jay is the one that wrote, Death of Auto-Tune, to protest all this pitch shifting.

But then again, if he's Nicki's ghost rapper, wouldn't that be the right move to throw us all off?

(hip hop music) - [Nahre] I've been hearing this sound everywhere.

- We just want to give a shout out to, that's Tayo O for taking the beat we do on our trap episode and remixing it and rapping over it.

Check it out.

("Black Cronkite" by Tayo O)