Vowel /ɪ/ is spelled <i> or <e> in beheaded and courses. The /eə/ diphthong is <air>, <are>, <ear> in swear, or <ar> in Sarah.
The contrast is not a problem for any known group of learners.
Interesting pairs include:
The mean density is very low 0.1%. The list makes 27 semantic contrast, giving a high loading of 93%.
beheaded bareheaded bid bared Billy barely bin bairn bins bairns biz bares chid chaired courses corsairs did dared dint daren't filly fairly finis fairness fizz fairs hid hared his hairs his hares id aired is airs kid cared kin cairn lid laird lids lairds Liz lairs Ms mares sirrah Sarah skid scared squid squared swiz swears whiz waresGeographical: Outside English-speaking countries, most visitors are from Hong Kong, Yemen, India, Vietnam, Spain, Malaysia and Poland. Average 5 visitors per month.
John Higgins, Shaftesbury, January 2011