"heir" is a much closer match for "hair" in terms of Levenshtein distance[1] (which indicates a typing error) and soundex[2] (misheard). But clearly "to err is human" should be offered as a possibility too.
[1] http://en.wikipedia.org/wiki/Levenshtein_distance
[2] http://en.wikipedia.org/wiki/Soundex
"heir" is a much closer match for "hair" in terms of Levenshtein distance[1] (which indicates a typing error) and soundex[2] (misheard). But clearly "to err is human" should be offered as a possibility too.
[1] http://en.wikipedia.org/wiki/Levenshtein_distance
[2] http://en.wikipedia.org/wiki/Soundex