This does not mean that that tone is the exclusive conveyor of meaning, merely that it is relevant. For example, many people are aware that there are four different tonal variations of the syllable /ma/ in Mandarin, which all have different meanings. I.e. there exists minimal pairs of words, where the only distinguishing difference is the tonal pattern.
Tonal languages are extremely common in Africa, East Asia, and Mexico, but rare elsewhere in Asia and in Europe; as many as seventy percent of world languages may be tonal.1
Now, the languages we are familiar with in SF (e.g. Klingon, Dothraki, LOTR languages) obviously come from Western traditions, where lexical tone is lacking.
Are there any invented languages in SFF that are tonal?
- Invented means it must have been developed to some significant degree, not just surmised.
- Tonal doesn't mean the meaning is conveyed only by tones; it means that tones, in combination with other variations in sound, are meaningful.