It takes a quick man three years to learn how to tune a piano well in equal temperament by estimation of ear . . . --Hermann Helmholtz, "On the Sensations of Tone," 1854

Bosendorfers, Steinways, Baldwins, Young Changs, Kimballs, Conns, Curriers, Evretts, pianos, pianos, every piano this side of your own little upright in the basement where your daughter played "The Volga Boatmen" for the relatives after $650 worth of lessons and you played the first six chords of "I Can't Get Started" after you broke up with whats-his-(or her-)name. They even have a Hsinghai here, straight from the People's Republic. Every piano under the sun is under the Capital Hilton roof, but no one is playing, just tuning up.

Here's the proclamation from Mayor Marion Barry written pianissimo bureaucrati. Maybe it tells the story:

"Whereas, members of the Piano Technicians Guild contribute to the quality of life in America and have a special relationship with our city . . ."

It's "Piano Technicians Week," and piano tuners and refurbishers have come from New Zealand, the Virgin Islands, Japan, China, Canada, the U.S. and other corners of God's Little Soundboard for the 25th annual convention of the Piano Technicians Guild.

As you enter the exhibition area of the convention, you see a small slide show on the Piano Technicians Hall of Fame. The blurb on Charles F. Stein gives an indication of the seriousness of purpose on display here.

Stein is the Vince Lombardi of piano tuning: "He was unforgiving to his students and without sympathy for anyone who wouldn't put the piano ahead of everything."

Everything!?

Tuning isn't everything, it's the only thing?

Apparently. Or at least it's a bigger deal than you thought. The tuners are attending classes like "Installation of Upright Hammers, Shanks & Butts," "Vertical Piano Troubleshooting" and "From the Bottom Up," "a slide presentation of four representative grand trap systems." The classes are somber affairs, featuring so many overhead projectors and schematic drawings that they begin to look like one of the seminars on nuclear fission in "Oppenheimer."

While just about everybody else is in class, taking notes, raising their hands, Hall of Famer John Travis, author of "A Guide to Restringing" and "Let's Tune Up," is manning a display booth.

"When piano tuners get together, they talk pianos and tell tuning stories," says Travis, a 55-year veteran of the business. Travis wears a black-and-white checked suit with a Hall of Fame pin on the lapel. The Piano Technicians Guild insignia, at first glance, looks like the family crest of the McSomebodys of the Hebrides, but on closer inspection the crossed swords above a gladiator's shield are a tuning fork and a tuning hammer crossed above a grand piano.

A shield of pride. "I love being a tuner and will tune pianos as long as the good Lord lets me," says Travis, who has readied pianos for Vladimir Horowitz, Rudolph Serkin and Arthur Rubinstein.

"You bet," says Elwyn Lamb, a 75-year-old Los Angeles tuner who has worked for the University of Southern California and Lawrence Welk. "It's a great profession. You always go in the front door. It's better than being a doctor, who's always with someone when they're sick, and better than being a lawyer, who's always with someone when they're in trouble. We help people make music."

"You bet," says Travis. "I love it. I once was tuning a piano for a Jascha Heifetz recital. You know the standard world tuning for 'A' above middle 'C' is A-440, 440 vibrations per second. Well, Heifetz wanted 444! So, I said 'Jascha, don't worry. Go back to your hotel. Relax. I'll fix it.' You know what? Hell, I didn't touch it! And everything went fine.

"Vladimir Horowitz. Now there's the grandest guy who ever was. Once we were looking for a buzz in his piano. We looked all over the place. We said, 'By Gosh, where is it?' And do you know that he just accidentally leaned his arm on the fall board and the buzz went away? Well, all I had to do was tighten it up a little and everything was fine. But he said the nicest thing to me. He said, 'I am the artist in the evening for the audience, but you, sir, are the artist behind the scenes.' "

Nearly three centuries ago, Cristofori invented the piano in Italy and, ever since, soundboards have been warping with the barometric pressures of the ages. It was no problem for Bach--he denounced the piano's touch as heavy and stayed with the organ. But Bach proved a better composer than trend setter. Elwyn Lamb says there are 12 million pianos in the living rooms, barrooms and concert halls of the United States, and every last one of them needs a tuning.

"Twice a year at least," says Lamb. "But if everyone who owned a piano in the country wanted a tuning that often, there wouldn't be enough of us to go around. It's not an easy skill."

The stereotypical piano tuner is an older man, preferably foreign-born, perhaps blind, who extracts clunkers using nothing but his ear.

"No way," says Travis. "There's no such thing as perfect pitch, just tonal memory. It's relative. You have to use a tuning fork."

No way, agrees Helmholtz. (What Harvey was to blood, Helmholtz was to the science of aural sensations.) "No ear knows a priori what result it has to expect, or has any means of judging whether the result obtained is correct."

Most of the tuners at the convention seemed to favor a more conservative tuning-fork-and-a-good-ear approach, but a few high tech booths were in evidence; technicians sampled Sight-O-Tuners, Accuforks and Dampits ("the sensational new humidifier") between classes.

And while coffee was being served, a few people crowded around the bulletin board to read a curious message:

"Mason N. Hamlin, D.D.S. Announces the Opening of an Office For The Exclusive Practice Of:

PIANO DENTISTRY"

No fooling. The photo shows Dr, Hamlin "extracting a badly decayed ivory from the keyboard of a fine old Franklin." It seems that Hamlin is sick of "unruly children" and "patients with bad breath" and has now turned (naturally) to "orthoklavic" procedures, "the drilling and filling of chipped ivories."

The message says you can call Dr. Hamlin at (212) 976-3838.

But all you'll get is Dial-A-Joke.