Which natural languages have the fewest phonemes?
Central Rotokas (https://en.wikipedia.org/wiki/Rotokas). It has five vowels (/a i u e o/) and three consonants (/p t k/), for a total of 8 phonemes.
Let's assume we count a phoneme as 1 sound and its allophones, and don't count tone and length differences as different phonemes. Then Rotokas (https://en.wikipedia.org/wiki/Rotokas_language) has 6 consonants and 5 vowels, for 11 total. Pirahã (https://en.wikipedia.org/wiki/Pirah%C3%A3_language#Phonology) has 10-12, depending on the source, under that definition. A commoner definition of phoneme would be a sound and its allophones, believing the ability to distinguish vowels with length and tone. That gives Pirahã 13-16 and Rotokas 14-16 A stingy definition, counting all occasional separate sounds, would give Pirahã 16 and Rotokas 19. Note: Hawaiian and other Polynesian languages often have limited inventories. For Hawai'ian, the common (middle) definition would give them 18 phonemes. Note: Conlangs, of course, have even fewer phonemes in some cases.
Keep in mind that tonal languages may have a relatively small number of phonemes, but that number is multiplied by a number of pitches or contours. Chinese languages/dialects are a prime example. [I should say: a relatively small number of vowels and consonants or other vocalizations, not a small number of phonemes.]
Polynesian languages have very few phonemes (such as Hawaiian, which has about a dozen). On the other end of the scale are Northwest Caucasian languages (the now extinct Ubykh and a dialect of Abkhaz).
its between rotokas as and pirahã depending on how you count
We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.
I created a language with only 9 phonemes: 3 vowels: |e, a, o| and six consonants: |p t k m n s| with no tones and V or CV syllables. take-ka toke te toke teke? (Do you want to speak the easy language?)