Pitch shifting

Key takeaways

Pitch shifting belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pitch shifting to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pitch shifting from memory before moving on to harder problems.

Reference excerpt

Pitch shifting is a sound recording technique in which the original pitch of a sound is raised or lowered. Effects units that raise or lower pitch by a pre-designated musical interval (transposition) are known as pitch shifters.

Pitch and time shifting The simplest methods are used to increase pitch and reduce durations or, conversely, reduce pitch and increase duration. This can be done by replaying a sound waveform at a different speed than it was recorded. It could be accomplished on an early reel-to-reel tape recorder by changing the diameter of the capstan or using a different motor. As for vinyl records, placing a finger on the turntable to give friction will slow it, while giving it a "spin" can advance it. As technologies improved, motor speed and pitch control could be achieved electronically by servo drive system circuits.

Pitch shifter and harmonizer

A pitch shifter is a sound effects unit that raises or lowers the pitch of an audio signal by a preset interval. For example, a pitch shifter set to increase the pitch by a fourth will raise each note three diatonic intervals above the notes actually played. Simple pitch shifters raise or lower the pitch by one or two octaves, while more sophisticated devices offer a range of interval alterations. Pitch shifters are included in most audio processors today. A harmonizer is a type of pitch shifter that combines the pitch-shifted signal with the original to create a two or more note harmony. The Eventide H910 Harmonizer, released in 1975, was one of the first commercially available pitch-shifters and digital multi-effects units. On November 10, 1976, Eventide filed a trademark registration for "Harmonizer" and continues to maintain its rights to the Harmonizer trademark today. In digital recording, pitch shifting is accomplished through digital signal processing. Older digital processors could often shift pitch only in post-production, whereas many modern devices using computer processing technology can change pitch values virtually in real time. Pitch correction is a form of pitch shifting and is found in software such as Auto-Tune and Melodyne to correct intonation inaccuracies in a recording or performance. Pitch shifting may raise or lower all sounds in a recording by the same amount, whereas in practice, pitch correction may make different changes from note to note.

DJing Pitch shifting can be used in DJing for harmonic mixing, a technique of matching the musical key of tracks in a DJ mix to avoid dissonance and create harmonious mixes or mashups. If a DJ wishes to mix two tracks which are not in compatible keys, they can shift the pitch of one track so that its key is compatible with the other, allowing seamless transitions between tracks which might otherwise sound dissonant when played together.

Notable uses Numerous cartoons have used pitch shifters to produce distinctive animal voices. Alvin and the Chipmunks recordings with David Seville (aka Ross Bagdasarian) were created by recording vocal tracks at slow speeds, then playing them back at normal speeds. Voice artist Mel Blanc used pitch shifting techniques to create the voices of Tweety and Daffy Duck. In the 1970s, reruns of shows like I Love Lucy were sped up in order to run more advertisements during commercial breaks. The Eventide H910 Harmonizer was used to downward pitch-shift the characters' voices back to normal after the episode was sped up. South Park creators Trey Parker and Matt Stone have used pitch shifting for most of their characters throughout the show's run. One notable early practitioner of pitch shifting in music is Chuck Berry, who used the technique to make his voice sound younger. Many of the Beatles' records from 1966 and 1967 were made by recording instrumental tracks a half-step higher and the vocals correspondingly low. Examples include "Rain", "I'm Only Sleeping", and "When I'm Sixty-Four". Electronic musician Burial is known for including pitch-shifted samples of vocal melodies in his songs. Goregrind and occasionally death metal use vocals that are often pitch-shifted to sound unnaturally low and guttural. The famous bass intro to the song "Seven Nation Army" by The White Stripes, is the result of guitarist Jack White playing an electric guitar through a pitch shifting effects pedal set to an octave below. The band was a duo, who lacked a bassist and had never previously used one in any of their music, choosing instead to mimic the sound of a bass guitar. From 1986 to 1988, American musician Prince used pitch shifting to create his “Camille” vocals. The coda in the song “The Bewlay Brothers” by David Bowie features Bowie's voice distorted by varispeeding; this effect also appears throughout Bowie's 1967 song “The Laughing Gnome”.

See also Audio time stretching and pitch scaling DigiTech Whammy Pitch control Puberphonia

References

External links Pitch shifting explained Time Stretching And Pitch Shifting of Audio Signals by Stephan M. Bernsee pitchshift.js from KievII Pitch shifter algorithm in JavaScript, from KievII library

Illustrations

Worked examples

Example 1 — a first encounter with Pitch shifting

Start with the simplest possible case. Write down what Pitch shifting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Pitch shifting before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Pitch shifting ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Pitch shifting

In research: Pitch shifting appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Pitch shifting in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Pitch shifting is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio engineering, Digital signal processing, Effects units, so understanding it makes those chapters shorter.
In everyday life: Look for Pitch shifting outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Pitch shifting in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pitch shifting means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Pitch shifting out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pitch shifting in simple terms?

Pitch shifting is a sound recording technique in which the original pitch of a sound is raised or lowered. Effects units that raise or lower pitch by a pre-designated musical interval (transposition) are known as pitch shifters.

Why does Pitch shifting matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Pitch shifting?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Pitch shifting.