These conjugations are correct.^^/ There are seven different types of irregular verb group in Korean such as.... 'ㅅ','ㄷ','ㅂ','르','우','러' irregular verb and 'ㅎ' irregular adjective. "듣다" belongs to the 'ㄷ' irregular verb group^^/ As for 'ㄷ' irregular verb, when it is followed by vowels, 'ㄷ' changes to 'ㄹ' 걷다 = to walk 걷 + 어(vowel = 'ㅇ' as in '어')서 = 걷 + 어서 = 걸+어서 걷 + 으(vowel = 'ㅇ' as in '으')면 = 걷 + 으면 = 걸+으면 걷 + 고(consonant = 'ㄱ' as in '고') = 걷 + 고 = 걷+고(doesn't change) 걷 + 을(vowel = 'ㅇ')수록 = 걷 + 을수록 = 걸+을수록 걷 + 었(vowel = 'ㅇ' as in '었' which is the past making particle)다 = 걷+었다 = 걸었다(walked) \^o^/

yeah. all are same meanings. that's just conjugation of Verb.