I've just read about the Saussure's second primordial principle that states that language is linear. This is sometimes interpreted as the notion of one-dimensioness of language. The second dimension indeed doesn't usually play a significant role in language, since written language is perfectly legible even without intonation and stress.
Is there a language that has this second dimension?
Here are two examples I'm wondering might be the case (you don't have to include them in your answer):
Tonal languages. Is the use of tone in those languages often enough so that the languages could be called two dimentional?
Click languages. Are the click consonants in click languages such as Xhosa being arranged so that they play a role of a standard phoneme, or can they play the role of the second layer of information?
I'll really appreciate an incomplete answer or an online literature recommendation since I understand this is a very broad question.