Soongsil University
IU possesses a soprano vocal range, with acoustician and professor Myung-jin Bae expressing her range also has mezzo-soprano qualities when writing an article comparing her voice to Hyun Bin. Her vocal ability is often met with positive reception. Monique Danao of "South China Morning Post" stated she could quickly transition from a "sweet" voice to "hit powerful notes". On his 2011 academic paper "The High-Pitched Analysis of IU" co-written by Doo-heon Kyon at Soongsil University, Bae used "Good Day" as the basis for it: he cited when IU reached the highest note (F♯5) in the 3-note increment, her stability in frequency showed a lengthy duration with abundant lung capacity and commented that IU "expresses well beyond the highest range required by the soprano [voice type]".