Babies are exposed even before birth to the sounds of their parents language, and they eventually work out, just by hearing, observing and imitating, how to pronounce words, what those words mean and eventually how those words can be strung together to form meaningful sentences. No one gives the baby specific instructions what to do with her teeth, lips, tongue and vocal chords to produce the sounds. No one is explaining verb conjugation to an eleven-month-old. Kids simply absorb the information. A child's brain is remarkably wired to learn that way.
Suzuki students also learn by ear, because they hear recordings and live performances of music (particularly the reference recordings of the pieces they will learn to play - which they should listen to as often as possible - several times a day, ideally), and learn more efficiently and more thoroughly than they ever would if merely given a series of rote instructions as to how to play the piece. A lot more.
- Grammar - We learn the complex systems of grammar in our native languages mainly by ear (not to mention the idiosyncrasies that might be specific to our households, neighborhoods or regions). We learn the rules of rhythm and harmony by ear as well. Even before we have the conceptual framework and vocabulary to explain why, we can tell when something sounds 'wrong.'
- Dialect - What kids learn by ear they learn with incredible detail. Kids who grow up in Boston learn to say "car" differently from kids who grow up in Nebraska. Kids who grow up in Georgia will stretch into two syllables words that kids in Washington state will pronounce with only one. In Wisconsin, where I went to college, the locals have a certain peculiarity (apart from their propensity to wear hats shaped like cheese wedges). What the rest of us refer to as a drinking fountain, Wisconsinites call a "bubbler." I had never heard of a "bubbler," I've met people in neighboring Illinois who have never heard of a "bubbler" and I met people in Wisconsin who had never heard of a "drinking fountain." The point is, regional dialects persist, they are by no means universal, they are incredibly complex and specific, and yet kids learn them anyway. In fact, there is no other way to pick up an accent than by hearing it. By the same token, music students can only learn subtleties of phrasing, style, articulation, tone, intonation, etc. by hearing music and hearing it often.
- Inflection - Consider the following sentence: "I enjoyed the symphony concert yesterday." It can be spoken several ways, each conveying a slightly different meaning, though the words are the same. We learn to pick up on these cues because we have been listening to people speak all our lives. In the same way, music students can learn how to express a musical phrase in a variety of meaningful ways, simply by listening.
- "I enjoyed the symphony concert yesterday" - implies that my companion did not.
- "I enjoyed the symphony concert yesterday" - refutes the suggestion that I did not enjoy the concert.
- "I enjoyed the symphony concert yesterday" - suggests that the string quartet on the previous program played out of tune.
- "I enjoyed the symphony concert yesterday" - implies that the performance was fun, but the dress rehearsal was brutal.
- "I enjoyed the symphony concert yesterday" - implies that the performance the day before was a complete disaster.
- Motivation - Babies hear adults and older kids speaking, and eventually develop the desire to speak as well. Musicians who listen frequently also develop a desire to play and to play beautifully and expressively.
- Self-evaluation - Children who listen are able to recognize when the sounds they are producing do not match the sounds they are trying to produce, and make adjustments accordingly.