Hartness is a proper noun that is spelt phonetically as "hɑːtnəs". The ‘h’ represents the initial sound followed by a long "a" sound, denoted by the symbol "ɑː". This is followed by the consonant "t" and then the vowel sound "ə", which is a schwa sound. The final sound is represented by the consonant symbol "s". Proper nouns such as Hartness usually follow their own spelling and pronunciation rules, which may not be the same as in regular words.