Method and Conclusion. See here.
Results. A ratings system was designed in terms of how difficult it would be for an English-language speaker to learn the language. In the case of English, English was judged according to how hard it would be for a non-English speaker to learn the language. Speaking, reading and writing were all considered.
Ratings: Languages are rated 1-6, easiest to hardest. 1 = easiest, 2 = moderately easy to average, 3 = average to moderately difficult, 4 = very difficult, 5 = extremely difficult, 6 = most difficult of all. Ratings are impressionistic.
Time needed. Time needed for an English language speaker to learn the language “reasonably well”: Level 1 languages = 3 months-1 year. Level 2 languages = 6 months-1 year. Level 3 languages = 1-2 years. Level 4 languages = 2 years. Level 5 languages = 3-4 years, but some may take longer. Level 6 languages = more than 4 years.
This post will look at the Taa language in terms of how difficult it would be for an English speaker to learn it.
!Xóõ (Taa), spoken by only 4,200 Bushmen in Botswana and Namibia, is a notoriously difficult Khoisan language replete with the notoriously impossible to comprehend click sounds. Taa has anywhere from 130 to 164 consonants, the largest phonemic inventory of any language. Of this vast wealth of sounds, there are anywhere from 30-64 different click sounds. There are five basic clicks and 17 accompanying ones. Speakers develop a lump on their larynx from making the click sounds.
In addition, there are four types of vowels: plain, pharyngealized, breathy-voiced and strident. On top of that, there are four tones. Taa appears on many lists of the wildest phonologies and craziest languages period on Earth.
Taa gets a 6 rating, hardest of all.