For those that are arguing that without vocabularly, it isn't considered a language:
From Wikipedia: Language is a system that consists of the development, acquisition, maintenance and use of complex systems of communication, particularly the human ability to do so; a language is any specific example of such a system.
I am aware that languages already exist today that use relative changes in pitch. This question is not about relative pitch; it is about absolute pitch.
In this country I've developed in my world, people without absolute pitch are treated akin to those with dyslexia or even autism, and have trouble communicating.
There are two forms of this language:
Phonemes + absolute pitch combination (common, simplified): This version uses words that are spoken at a pre-defined set of absolute pitches. (for this question let's say the notes are a classic Western 12-tone equal temperament )
Octaves are treated the same. For example, there's no difference between C3 and C4. In this context, "octaves" refers to any notes that have dominant frequencies with a "power of 2" relationship. ($\times2$, $\times4$, $\times8$, $\times\frac{1}{2}$, $\times\frac{1}{4}$, $\times\frac{1}{8}$, etc.)
Just like the order of words/phonemes is meaningful in most — if not all — languages, the order of note pitches is meaningful for this language. A C note followed by an A note will mean something different than an A note followed by a C note, even if the same words/phonemes are used.
Absolute pitch (advanced, less common): This version does not rely on phonemes at all. People can simply hum a note or even play a note on an instrument.
- The absolute pitch matters and is dependent upon the dominant frequencies. Like the previous version, octaves are considered the same.
- And just like the previous version, the order of note pitches is meaningful.
- However, the length of notes is important in this version. The length of time that a note is held will mean different things. It is also relative, and each note compares its length to the note before and after it. For example, as long as one note is longer or shorter than the note before it, it doesn't matter how long the note is held. So a 2-second note followed by a 1-second note is the same as a 3-second note followed by a 2-second note, assuming the notes are the same pitch and in the same order.
Since notes have lingual significance for this country's culture:
Could music develop in this language?
To outside countries, this language would sound bizarre, with seemingly random notes that might be annoying to listen to. And to this country, music from outside countries would just sound like a particularly bad day of Google Translate and would be cringe-worthy to them.
My definition for what "music" is is based upon modern-day music, particularly that of Western and Asian countries such as the United States, South Korea, etc. which use 12-tone equal temperament.
NOTE: Although the question The alphabet of a language based on pitch and vocabulary involves a similar language, I am not concerned with the alphabet of my language at this time.