My Training and Experience
"By Ear" or With Machine?
I was trained to tune "aurally," which means using a tuning fork to get the pitch of one note and then tuning all the other notes in relative relationship to that note. (See my pages on "Tuning".)
At the time I was trained, there were no electronic devices that could provide a tuning as good as my aural tunings. I tuned only aurally for about 20 years. In 2002, a piano technician and electronics expert designed new software (Verituner™) which can "listen to" all the harmonics of a specific piano and then calculate the best tuning for that piano. I now use this device. When a piano is considerably flat or sharp, the Verituner software can compensate for this quite accurately, and often avoids my having to do a separate "pitch raise". It is also especially helpful when there is background noise. The tunings that result when I use this software are not better than my aural tunings, and I -- not the software -- am still tuning the piano. The software is an aid.
If a piano tuner is using an inexpensive, older electronic device, that machine cannot provide an excellent tuning. I still believe that if a tuner cannot tune at all by ear it is an indication that s/he has not been willing to invest the time and energy into learning this skill and that the tuner cannot tell the difference between a bad tuning, a good tuning, and an excellent tuning. Using a good electronic aid can help create a good tuning only if the technician has learned good tuning technique, and only if the technician can do aural checks. The machine does not tune the piano, the technician still tunes the piano.
In addition, whether tuning with or without any electronic aid, if a tuner has not been taught other important aspects of tuning, s/he will not be able to provide an excellent and stable tuning. In other words, if you bought a Verituner, you still would not be able to tune your piano correctly, or have it stay in tune after you were through. (If you would like to spend $1500 and try, here is the Verituner web site!)
A competent piano technician should also be able to maintain the mechanical parts of your piano properly, to keep it playing and sounding its best.