Thus, one standard solution is needed (e.g. HCl) in the direct titration, while two are needed (e.g. HCl and NaOH) in the back-titration.
ðˈʌs, wˈʌn stˈændɚd səlˈuːʃən ɪz nˈiːdᵻd ˈiː.dʒˈiː. ˌeɪtʃsˌiːˈɛl ɪnðə dᵻɹˈɛkt taɪtɹˈeɪʃən, wˌaɪl tˈuː ɑːɹ nˈiːdᵻd ˈiː.dʒˈiː. ˌeɪtʃsˌiːˈɛl ænd nˈɑː ˌoʊˈeɪtʃ ɪnðə bˈæktaɪtɹˈeɪʃən.