Possibly the most revolutionary change in piano technology has been the widespread acceptance of the electronic tuning device. Electronic tuning devices, or ETDs, have been around for years, but with the more recent advancements in technology they have become commonplace to the point that most piano tuners use them. (Full disclosure: I do too.)
30 years ago most tuners tuned by ear, and the first “Sanderson Accu-Tuners” were beginning to be produced and sold for about $1,000 each. (This is in the early 1980s.) Today the “Accu-Tuner IV” goes for about $1,600, but there are other options available as well. “Cybertuner”, “Verituner”, and “Tune Lab” apps are available in the Apple app store for $1,000, $600, and $300 respectively, and can be downloaded onto any iPhone or iPod, making a convenient tuning device. (In my experience, Cybertuner, Verituner, and Accu-Tuner all produce very high quality tunings, while Tune Lab has some problems around the tenor section.) This tuning software, combined with the huge advances in mobile technology, have effectively lowered the barrier of entry to become a piano tuner.
Electronic tuning devices make piano tuning easier, simply put. It’s possible now to get a very good tuning without counting and comparing beats or setting a temperament. Pitch raises are easier too. The downside is, well, it’s too easy. Anybody can download a $300 app, buy a cheap $35 wrench on ebay, call themselves a “piano tuner”, and start charging people $120+ for tunings. Don’t get me wrong, some people who do this might actually tune well, but my fear is that many won’t. The software will be a crutch. In relying so much on sight, and having never learned how to use their ears, tuners will make mistakes without even knowing it. Without having spent hours listening for beats in thirds, sixths, fourths, and even fifths, they won’t know which checks to use where, whether intervals are supposed to be wide or narrow, and won’t know the harmonic series by heart. The other downside will be the tuners who only tune and don’t know how to fix anything else. (These are what some piano technicians call “tooners”.) When it’s no longer necessary to go to school, or at least undergo a formal apprenticeship to become a piano tuner, these charlatans will proliferate. (Yes, humor was intended there.)
Just to be clear, I believe that the best tunings come from using a combination of aural and ETD-assisted tuning. Also, if you are reading this and are thinking about becoming a piano tuner/technician, may I highly recommend that your first purchase be a book, not an app. Learn the hard way, and it will pay off, and consider apprenticing yourself to an established technician or enrolling in a piano technology school or program. If you are someone who wants your piano tuned, my advice to you is to make sure your piano technician knows what he or she is doing. If they tune your piano without making any repairs or other improvements, that might mean something.
One last note about tuners: The $300 app, so far as I know, is the cheapest app that can tune a piano. The free tuning apps in the app store or Android market, or guitar/violin tuners are most definitely not for pianos, and won’t be able to tune a piano. Real tuning devices or software must account for inharmonicity, and should be able to be precisely calibrated to an accurate frequency source.
Addendum: 4 years after writing this post I have published a new Android app for tuning pianos called Easy Piano Tuner. It measures inharmonicity, as described above, and calculates a custom tuning curve for each piano. The app is free to try, and will cost about $100 to unlock the full “professional” functionality and only $20 to unlock the functionality of tuning an entire piano.