Whether they are called La Si Do Ré Mi Fa Sol, A B C D E F G or ハ ニ ホ ヘ ト イ ロ, the notes refer to the same sound height, to the same keys on a piano. If they don’t have a universal designation, it is because they are all derived from a heritage proper to each civilization and each language.
A B C : it’s easy as 1 2 3
The idea of associating the notes to alphabetical characters wasn't born yesterday... Already 300 years before our era, Greeks transcribed their musical compositions using letters, numbers and varied symbols. There were many symbols of notation. During the antique period alone, we counted almost 1260 signs in use.
Confronted with this mess, Boethius, a Latin philosopher, set about bringing order to these symbols. At the turn of the 6th century, he decided to associate the first 15 letters of the Latin alphabet to 15 ascending notes. This system would later be reduced to the octave, from A to G : seven letters that Anglo-Saxons and Germans still use today.
Yet, at the time of Boethius, a letter was not in reference to a fixed note: it referred to the relative height of a sound (B in relation to A). The action of systematically associating A B C D E F G to the scale, from the La to the Sol, was set almost 500 years later, during the 10th century, by Benedictine monk Odo of Cluny.
E, it's easy to sing
But if people speaking a Latin tongue were asked today to sing the scale of the notes using letters, they would probably be lost. In the Latin countries, the names of the notes Do Ré Mi Fa Sol La Si are not the heritage of Antiquity and Boethius: they were shaped by the vocal music.
Isn't it indeed easier to sing an interval - the gap between two notes - when one can associate it to a word and a melody? Try singing a fourth in tune! It can seem difficult and yet, you just need to sing the first notes of La Marseillaise. A second descending major ? Simple: Yesterday by the Beatles.
It was Guido d’Arezzo - also a benedictine monk, but Italian this time – who discovered this trick at the beginning of the 11th century. Except of course that in his lifetime, there was no national anthem or hits sung by four boys in the wind... To make the learning for the singers in his abbey easier, the pedagogue chose the Anthem to St John the Baptist widely known among the monks.
_UT_queant laxis / To allow
REsonare fibris / the strings to sound
MIra gestorum / relaxed to our lipes
FAmili tuorum, / the wonders of your actions,
SOLve polluti / take away the sin
LAbii reatum, / of your impure servant
Sancte Johannes / Saint John
We notice that the first syllables of each verse are the names of the notes still in use today in Latin countries. There are two differences though: the "SJ" was adapted to French and transformed into "SI" by Anselm of Flanders in the 16th century. The "Do" was created during the following century and replaced the Ut that Italians found to difficult to pronounce.
The Anglo-Germanic resistance
When the use of Do Ré Mi Fa Sol La Si spread throughout Europe, why did the Anglo-Saxon and Germanic countries keep the use of the alphabetical order ? The first answer is the most obvious: the mnemonic trick of the monk d'Arezzo works with Latin and therefore, can less easily be adapted to languages of Germanic origins.
The second lead came later: England and Germany are two countries where piano manufacture widely developed, especially during the Romantic period. And, there was only a small space beside the ankles of the instrument to facilitate the work of the tuners. Just enough to write A B C D E F and G.
We still have to point out a difference between Anglo-Saxons and Germans: for the former, the B refers to the Si, whereas for the latter, it's the H that refer to the Si. Our friends from Germany in fact kept the Latin use of the B for the Si bémol. Otherwise, it would have been too easy...
Our Germanic friends have another specificity: they like to compose, starting from the words. Bach therefore created his Art of the Fugue from the letters of his own name (in Latin notes Sib La Do Si). Schumann also liked to play with language and sounds. For example, he wrote variations around a theme made from his imaginary friend's name: Meta Abegg.
What about the rest of the world ?
From the A to the G, the seven notes of the Japanese scale are associated to the first characters of the iroha, a sorting used to learn the calligraphy. This order is not the same as an alphabetical one, since a succession of signs doesn't form a syllable. The iroha, the chant of the iroha to be more precise, was in fact transcribed by a sūtra buddhist.
India is another example. The swaras are also seven in total, each note referring to the sound made by an animal: the shadjamam is the call of the peacock, the richabhami is the mooing of the cow, the gandharam is the bleating of the goat, the madhyamam is the call of the heron, the panchamam is the sing of the nightingale, the dhaivatam is the neigh of the horse and the nichadam is the trumpet of the elephant.
When written down, those notes are reduced to S R G M P D N and when they are sung, they are simply pronounced Sa, Ri, Ga, Ma Pa, Dha and Ni. Indian notes therefore have the commodity of combining the two aspects when, in the West, the linguistic ABC is distinguished from the Latin solmisation: the concision in the writing of the first system and the help for singing of the second.