There has always been a good deal of mystery surrounding the pinch harmonic, or, as hip players like to call it, "pick squeal". A pick squeal is simply an artificial harmonic, or high-pitched sound, produced by choking up on the pick and allowing the thumb or thumbnail to catch the string in just as it is picked. The result, of course, resembles a squeal. Or a squawk. Or a scream. Anyhow, what was once the domain of blues-rock string benders is now a staple for most metal guitarists. Here be the dudes who made it so.
10. Greg Howe
Sure he’s moved on to smoother and faster fusion pastures, but early on in his rock career, velocity merchant Greg Howe used the pinch harmonic like it was going out of style. Listen to Howe II to hear him bend notes into frequencies perceptible only by canines. Sure, it went out of style. But it came back.
09. John Sykes:
A speed freak of the scalar variety, Sykes really showed his know-how for the squeal upon joining Thin Lizzy for their 1983 swan song Thunder And Lightning. The repeated, howling fills in "Cold Sweat" were the precursor of the exaggerated squeals that became rampant in metal guitar playing during the decade. Later, Sykes would Top 40-fy the technique on Whitesnake’s "Still Of The Night."
08. Shadows Fall:
Jonathan Donais and Matthew Bachand haven’t merely led the return of melodic thrash to the America. No. They’ve punctuated their intricate leads with pinch harmonics, helping to bring the technique back into prominence in extremely heavy music. It’s like havin’ Zakk Wylde and John Sykes in one band!
07. Skid Row:
A Skid Row song without a scream or 300 from the guitar just wasn’t complete. In fact, the band’s self-titled debut may have more pick squeals than Van Halen had David Lee Roth squeals. And speaking of frontmen, the pinch harmonics of guitarists Scotti Hill and Snake Sabo were the antidote Sebastian Bach Eighties-metal wailing.
06. Eddie Van Halen:
Look no further than Van Halen’s landmark debut. With his aggressive pick attack, Ed sounds almost as if he’s using some weird wah-wah effect when he pinches the strings in the hyperboogie riffs of "I’m the One" and "Jamie’s Crying." And how about the opening riff of "Ain’t Talkin’ Bout Love"? Rock guitar changed at this point.
05. Dimebag Darrell:
By the time Pantera made the transformation to Metallica-inspired power metal, the Dime had moved from inserting EVH squeals in his solos to writing riffs around pinch harmonics, as in "Cemetary Gates." When that song came out, death-metal bands immediately started taking their cues from Mr. Abbott.
04. Steve Vai:
The Big V has been making weird guitar noises since his infancy—when Frank Zappa’s wolf pack adopted and raised him. But it all came together, pinchwise, on Flexable’s chromatic tour de force "Attitude Song." Later, Vai merged commercial success, whammy bar, and pick squeals on David Lee Roth’s version of "Tobacco Road," and the technique all but dominated the boogie tune "Juice," from Alien Love Secrets.
03. Roy Buchanan:
The late and lamented Buchanan gets credit for inventing the technique, back in the Sixties. The way he laid into his strings made it so that virtually every bend had a harmonic overtone of some sort. Yep, he was chicken pickin’, and the notes they were squawkin’. Some of his most over-the-top pinch harmonics—produced without the aid of ridiculous distortion—can be found on the album Live Stock.
02. Zakk Wylde:
A 19-year-old feller rejuvenates Ozzy’s band by twisting steroid-enhanced riffs into "Miracle Man" and interspersing pick squeals in just about any gap that opens up. Wylde realized he was onto something; the technique is now integral to his rowdy playing style. Indeed, when he touches off his A squeal, it sounds as though the string is screaming for help.
01. Billy Gibbons:
The fact that The Beard sustained a large portion of his "La Grange" solo with harmonic squeals puts him in the books as a master of the technique. The fact that song is a tribute to a house of ill repute makes the sound effects—the squeals—ever more appropriate. According to lore, Gibbons attains his signature squeals by picking with an old coin. The thicker the pick, the louder the squeal louder, or so they say.
Thanks for the report to GuitarWorld.com.
he was one of the earliest to use it anyway, and La Grange was a pretty influential song. And yeah, I'd have liked to see KsE in there too. Oh well.
!!!!! 
Great to see The Rev. Willy G. get the top spot. I am a huge fan of ZZ Top and he deserves it.