bˌʌt ɪnðə lˈeɪɾɚ jˈɪɹz ʌvðə mˈɔːɹɡɪdʒ, wˌɛn ðə pɹˈɪnsɪpəl hɐz ɔːlɹˌɛdi bˌɪn səbstˈænʃəli pˈeɪd dˌaʊn ænd nˌɑːt mˈʌtʃ mˈʌnθli ˈɪntɹɛst nˈiːdz təbi pˈeɪd, mˈoʊst əv ðə mˈʌnθli pˈeɪmənt ɡoʊz təwˈɔːɹd ɹᵻpˈeɪmənt ʌvðə pɹˈɪnsɪpəl, ænd ðə ɹᵻmˈeɪnɪŋ pɹˈɪnsɪpəl dᵻklˈaɪnz ɹˈæpɪdli.
But in the later years of the mortgage, when the principal has already been substantially paid down and not much monthly interest needs to be paid, most of the monthly payment goes toward repayment of the principal, and the remaining principal declines rapidly.