There's so much to learn when it comes to piano tuning; note names, intervals, equal temperament, inharmonicity, coincident partials, check notes, temperament sequences, stretch, octave sizes, stability, setting the string, setting the pin, the list goes on.
The piano tuning student is advised to identify these skills into one of two categories:
1) Things that I can learn faster if I spend more time studying it.
2) Things that I cannot speed up learning much at all.
Things in the first group are intelectual things; book things like memorizing intervals, order of notes, sequences, etc. The more time you spend trying to memorize these things, the faster you will learn them.
The 2nd group deals with things the body needs to learn; things that you need to perform, like hammer technique, etc.
The number one most often overlooked skill that you need to develop is being able to hear beats. (Beats being the pulsations in volume created by two frequencies that are very close but not exactly the same.)
The reason why this skill is over looked is because often people seem to get the feeing that they hear something and so they thing they don't need to work on it.
For example, every single time I have a student send me in a recording of their unisons, the unisons need to be sent back to be redone.
Think about that.
The standard technique for tuning unisons is to try and tune higher partials beatless because whatever speed the higher partials beat, the lower partials will beat slower.
So if a student sends me in a unison that they think is clean, it's because to their ear, the higher partials are beatless, yet when we perform a simple bandpass filter on the unison, we can easily hear a higher partial beating but not just beating, but sometimes beating fast.
Do you see the insipid diabolical situation here? You can't hear what you can't hear!
Not only can you not be able to tune the unisons clean because you can't hear the beating higher partials, but you actually think the ARE clean because you can't hear the beating higher partials.
It invariably leads to the embarrassing situation where a fellow technician, or worse, a customer, has to point your bad unisons out to you. (This has happened to every young piano tuner.)
Read the blog post entitled "How to Hear Beats More Easily" for some easy things you can do to help you hear beats.
There are basically two types of techniques you can use to help you hear beats more easily.
1) Techniques that are in real-time that I will call "active techniques", and
2) Techniques that require you to perform an extra step to get the feedback which I will call "passive techniques".
Real-time techniques like ghosting, focusing your ear, turning your head, cupping your hand, are iffy because sometimes they work and sometimes they don't work because ultimately they require the internal wiring of your ear to still do the majority of the work, wiring that may not have developed yet, or conditions don't exist for the techniques to work well.
Passive techniques like recording and filtering can be really amazing because they are designed to produce a clean beat that is easily heard. However, they are really only good for training; because the huge amount of time added to a tuning, they are not practical.
Except for the Piano Tuners Ear.
The Piano Tuners Ear is the only active, real-time technique that can be used at the piano, during an actual tuning. The Piano Tuners Ear produces clean, audible beats in real-time that allow the technician to make immediate decisions on how to tune each note.
Be sure to watch the videos in the free piano tuning course to see the Piano Tuners Ear in action.