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'''''Pitch Shifting'' alters the pitch of your playing.'''{{Top-Level Crumbs|4}}{{Gear Crumbs|4}}{{Effects Crumbs|10}}
There are two basic kinds: '''chromaticPitch Shifting''' (or stepwise) and '''harmony''' (or ''intelligent'', or sometimes called a ''harmonizer''). '''Chromatic simply shifts alters the pitch by some set amount''', usually specified in terms of a chromatic interval (m2, M2, m3, M3, etc.), but often also allowing a continuous range of values in between the intervalsyour playing.
Additionally, there are devices that are not dedicated ''Chromatic'' simply shifts the pitch shiftersby some set amount, but make use usually specified in terms of pitch shiftinga chromatic interval (m2, M2, m3, M3, etc.), such as octavers and some kinds but often also allowing a continuous range of reverb/delayvalues in between the intervals.
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There are two basic kinds: '''chromatic'''A Harmony (or stepwise) and ''Intelligent'harmony') pitch shifter shifts the frequency by an interval of an ''unspecified(or '' quality (2nd, 3rd, 4th, etc.). It detects the pitch of the note being played and uses the corresponding interval in the scale selected'intelligent'''. For instance, if you use the scale of C Major with or sometimes called a shift of a 3rd and play a C note, the shifter would output an E, a M3 above C. However, if you played an A, it would output a C which is only a m3 above A. Advanced intelligent shifters allow various scales beyond all the Major and Natural Minor scales, such as Harmonic Minor (and some even allow you to program your own custom scales, including using tunings outside of equal temperament'''harmonizer''').
A ''Harmony'' (or Intelligent) pitch shifter shifts the frequency by an interval of an ''unspecified'' quality (2nd, 3rd, 4th, etc.). It detects the pitch of the note being played and uses the corresponding interval in the scale selected. For instance, if you use the scale of C Major with a shift of a 3rd and play a C note, the shifter would output an E, a M3 above C. However, if you played an A, it would output a C which is only a m3 above A. Advanced intelligent shifters allow various scales beyond all the major and natural minor scales, such as harmonic minor (and some even allow you to program your own custom scales, including tuning outside of equal temperament). Additionally, there are devices that are not dedicated pitch shifters, but make use of pitch shifting, such as '''octavers''' and some kinds of reverb/delay. While uncommon to guitar, '''auto-tuners''' or '''pitch correctors''' are also pitch shifters that detect the pitch of an input and shift it to match the pitch of the closest note within a given scale. I will not cover them here.
== Quality Considerations ==
Harmonizers additionally have the difficulty of detecting the pitch you are playing, which has to occur before it knows by how much to shift the pitch. This analysis requires buffering and analyzing a segment of audio, which can lead to greater latency than a simple chromatic shift. Many chromatic shifts, however, also use pitch tracking to assist in reducing artifacts and smoothing output, which again can lead to lag.
Your guitar signal isn't a periodic waveform like a perfect sine wave, but real-world audio with changing waveforms, even when a single note is sustained without vibrato. Sped-up audio segments must be repeated to consume the same amount of time as their original length. Slowed-down segments must be chopped, so they don't consume more time than the original segment. Additionally, piecing together segments can get ugly- in order to align the phase, pitch must be detected...but what about those noisy transients?
Even when using "nice" intervals like octaves, the shifting process leaves lots of artifacts in the tone. If you have two shifters available, try shifting up an octave then back down to the original note. It will likely sound nothing like the original note. Using less harmonic intervals will fare even worse. '''A good pitch shifter minimizes artifacts, or makes the artifacts somewhat musical, rather than crackly or overly alien-sounding.'''
== Advanced Features ==
=== Formant/Vowelizer ===
Some shifters allow you to target resonant peaks called '''formants'''. These are typically associated with the human voice, ''particularly vowels''. The shape of the mouth used to make vowels forms resonant peaks, which gives each vowel its particular sound, regardless of its actual pitch (although it does have to have a fundamental pitch below the formant peaks). By applying such peaks to the pitch shifted tone, you get a more vowel-y sound, with the tone resembling the human voice among other instruments.
=== Pure Tuning ===
For a harmony shifter, some have the option of using '''pure tuning''' rather than equal termperamenttemperament. See [[Equal Temperament and Alternate Tunings]] for more about the difference. Pure tuning is recommended - it will use the more harmonious ratios for the desired intervals, avoiding the beating that occurs when intervals slightly diverge from their pure interval ratio.
=== Special/User-Defined Scales ===
Simpler harmonizers only allow harmonizing against Major major and Natural Minor natural minor scales. More advanced ones will give greater scale options or even allow you to define a '''custom scale'''. This could be used for advanced/special scales such as Harmonic Minorharmonic minor, Jazz Minorjazz minor, Double Harmonicdouble harmonic, or Hungarian Minorminor.
Some go even further, allowing you to specify scale notes in terms of cents away from their equal temperament tuning. This would allow you to harmonize in ancient Greek scales, for instance.
=== Sequencers ===
Some pitch effects may have a [[Sequencers|''step sequencer'']], with different intervals programmed against a tempo.
== Advice ==
=== Harmony Lines ===
A harmonizer is designed to play at a near equal dry/wet mix, so it sounds like two guitars playing in harmony. You can use 4ths or 5ths, but these are most often P4 and P5 intervals, at least in the common Majormajor/Natural Minor natural minor scales. More interesting is 3rds or 6ths. 2nds and 7ths can be a bit dissonant.
Usually, harmony lines are played like leads, in higher registers. This, combined with delay/reverb can mask any pitch shifting artifacts fairly well.
=== Digital Sound ===
The artifacts from pitch shifting can sometimes be desirable to create a "digital" sound, as if you are not actually playing guitar. Using high mix and multiple intervals, especially with a step sequencer or formant option can really mask the nature of the guitar. This is more emphasized when placed after distortion, but works even in front of distortion or on a clean tone.
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