Is music a language?
The characteristics that define a language are letters, groups of letters defining something (words), and grammar. In music, the letters are the notes; the words are the base components of melody (bar forms, etc.); and the grammar are the harmonic or counterpoint rules. Therefore, music could be defined as a language.
The issue arises when we recognize that music has only 7 letters, which are apparently not enough to represent the whole reality. Moreover, despite many people play music, nobody ever associated physical things to notes. Therefore, it is quite difficult if we were to translate from a generic language to music or vice versa.
To understand how we could make it work, we need to understand the potential of music first. As we already know that music represents the cosmos and is somehow a sort of holy language, we will compare it to the Holy Language for excellence - Hebrew. It is a tradition that the language used by God to speak the world into existence was Hebrew. Therefore, an object identifies itself with its Hebrew naming and there is no difference between the blueprint in God's mind (the net of oscillations or superstrings that are behind the matter making up such an object) and the object itself. In all the other languages, words are merely a reference to an object, not the object itself. And this is the big difference between the Holy Language and a general language.
One of the most ancient books - Sefer Yetzirah (The Book of Formation) - explains that the 22 letters of the Hebrew alphabet are subdivided into 3 mothers, 7 double letters, and 12 simple letters. This is astonishingly similar to the musical alphabet: We have 3 causes, 7 notes, and 12 semitones.
If we take a closer look, the 3 "mothers" are exactly "causes". In fact, the symbol of the mother is chosen because the woman bears children. Therefore, she is the causative element that promotes the species.
The 7 doubles are explained as having a double meaning, one in the good and one in the bad, one being the opposite of another. This matches perfectly with the 7 notes, which can be used either in the major or in the minor mode, with an opposite meaning.
Finally, Sefer Yetzirah relates the 12 simple letters to the zodiacal signs and the directions. They have only one unequivocal meaning, and therefore they are called "simple". The semitones have likewise one single meaning. They are not subjected to modes.
Moreover, in Hebrew letters are also numbers. This also happens with notes. It is common to call the notes of a certain scale with their number - for example, the fourth degree of the scale, to refer to the note that is four places above the fundamental.
With all these similarities, the Holy Language and Music seem the same thing. The only difference is that, practically, the former uses all 22 letters in speech, while the latter only uses 7 - despite always in the context of 3 and 12.
We also learn from the Bible that God has many names. His main name is four-lettered, but his extended name is 72 letters. Therefore, a language can be enlarged or shrinked too, as the need arises.
We can think of music as a Condensed Holy Language, which is indeed very fit to represent the entire Creation at a macroscopic level. It may lack all the details of a broader language, but the fact that it is condensed forces it to use a "stronger voice" - stronger and bigger concepts. If we were to express those concepts via a general language, we would use much more words than with music - often, simply with the same outcome.
With general speech, a lot of words are wasted to explain the details of a concept, so that the listener can build a representation in his mind of that which the talker is explaining. The idea that forms in the listener's mind in just a fraction of the words used by the talker, and mostly only a bigger summarized idea remains. Music jumps straight to the mind and heart, avoiding all those unuseful details and conveying the general meaning. Of course, sometimes the mind needs to understand what the feelings tell it, and not all are able to translate music into their daily language, in order to explain it. However, this does not detract from the received message.