will make the vocal track sound like a cartoon chipmunk . If we wanted to create the sound of that male vocalist actually sounding like he was that human singing up an octave , we ’ d need to account for the unique formants of his particular voice . Although I ’ m mixing metaphors a bit , one way to think of a formant is like the sonic fingerprint of a given source . The fancy technical definition ( via Wikipedia ) for formant is “ the broad spectral maximum that results from an acoustic resonance of the human vocal tract .” As we all know from our work on adjusting the EQ of different sources , there are certain frequencies that tend to be readily excitable and accentuated or attenuated across the sonic spectrum . If we simply double the frequency of a source without accounting for the particulars of these ‘ acoustic resonances ’, we end up with chipmunks from human voices . If we include some formant ‘ corrections ’, we can add back some of the variables that are in play for a given source and end up with something that is more human-like and less obviously tweaked .
As Woody Allen highlighted , there is probably a lot more to this that is necessary to study in order to really draw out the technical details . I recommend Perry R . Cook ’ s PhD dissertation with the snazzy title ‘ Identification of control parameters in an articulatory vocal tract model , with applications to the synthesis of singing ’ as a good starting point if you are really curious ( 1990 ). But even without this technical deep dive , we can turn to a few different example scenarios to give us a feel of how we might use formants to our mixing advantage .
Let ’ s imagine that you have two male background vocalists in your worship band and need to use pitch correction to thicken up the sound and artificially create a ‘ female ’ vocal line in the mix . As we ’ ve noted , you probably don ’ t want a chipmunk to join the praise band . Sure , they ’ ll work for peanuts — but their particular vocal qualities aren ’ t likely what the worship leader had in mind . In this case , we can adjust the formant on the generated octave up ‘ correction ’ of the male background vocalist to sound more like a female singer . We could also run this in the other direction if we had female vocalists and wanted to weave in something closer to the sound of a male tenor voice . To get a better sense of this effect in action , visit the Allen & Heath Vocal Processing webpage and play with some of the wet / dry settings on the audio examples : https :// www . allen-heath . com / hardware / dlive-series / rackultra-fx / vocalprocessing /
PUTTING IT ALL TOGETHER As noted in Part 1 of this series , there are a number of plugin suites available that offer this sort of formant correction . Allen & Heath offers a number of native pitch correction effects within the latest dLive V2.0 update ( via the RackUltra FX card ) to insert vocal processing within the console in realtime . As the website explains , “ Vocal Shifter radically alters vocals with a formant control and the ability to shift the vocal up or down by up to 12 semitones . Vocal Shifter can produce anything from pitch doubling to the unreal robotic and ageing effects heard in EDM and other electronic genres .” This ‘ shifting ’ effect includes a formant control so that you can decide how you ’ d like to color ( or ‘ age ’ or ‘ robotify ’) the signal according to your needs . “ Vocal Tuner is designed for natural sounding pitch correction , with minimal audible artifacts , suitable for all genres of music , and any situation where the performer may need a gentle helping hand .” This more simple tuning effect doesn ’ t include the complex formant parameter adjustments and as noted is more of a ‘ minimal ’ helper for really subtle pitch correction in more of an exposed solo ( perhaps lead vocalist ) scenario . “ Vocal Gridder produces faster , less natural-sounding pitch correction – as heard on countless hip-hop , pop , trap , and modern country productions – where notes “ snap ” to the target pitch almost instantly .” We ’ ll get more into the other pitch correction concepts in Part 3 of this series ,
but if Vocal Shifter is more about the ‘ shape ’ of the signal frequency formants , Vocal Gridder is more about the temporal ( timing ) aspects of the corrections . None of these descriptions are hard and fast rules , but hopefully they can serve as a good starting point to get our heads around pitch correction overall .
In short , if you don ’ t want a scurry of chipmunks up on the stage on Sunday , you ’ ll need to understand formants . And yes , a group of chipmunks is called a scurry . Now I need to dust off the ol ’ Chipmunk Punk album and get out my dancing shoes — see you next month for Part 3 as we dig into the fun topic of pitch correction in live sound .
Jeff Hawley A 20 + year music industry veteran — equally at ease behind the console , playing bass guitar , leading marketing teams or designing award-winning audio products . He currently heads up the marketing for Allen & Heath in the US .
96 September 2024 Subscribe for Free ...