ðɪ ˌʌndɚlˈaɪɪŋ aɪdˈiə ɪz ðætðɪ ˈiːvənˈɪndɛks sʌbtɹˈænsfɔːɹm ʌv ɹˈeɪdɪks tˈuː hɐz nˈoʊ mˌʌltɪplˈɪkətˌɪv fˈæktɚɹ ɪn fɹˈʌnt ʌv ɪt, sˌoʊ ɪt ʃˌʊd biː lˈɛft ˌæzˌɪz, wˌaɪl ðɪ ˈɑːdˈɪndɛks sʌbtɹˈænsfɔːɹm ʌv ɹˈeɪdɪks tˈuː bˈɛnɪfˌɪts baɪ kəmbˈaɪnɪŋ ɐ sˈɛkənd ɹᵻkˈɜːsɪv sˌʌbdᵻvˈɪʒən.
(The underlying idea is that the even-index subtransform of radix-2 has no multiplicative factor in front of it, so it should be left as-is, while the odd-index subtransform of radix-2 benefits by combining a second recursive subdivision.)