He plays also Pianoforte and Ondes-Martenot in addition to piano, harpsichord and organ.

 "[Ooi] sort glorieux d'un double combat, contre l'orchestre et contre une écriture pianistique à la limite du jouable." (P. Rigaudiere/ Diapason)
 "...the pianistic acrobatics of Hiroaki Ooi, who makes light of the extreme demands of the work, ..."(M. Coston/ BBC Music Magazine)
 "Impresa davvero eroica" (P. Petazzi/ Il Gazzettino)
 Born and brought up in Kyoto, Hiroaki Ooi moved to Switzerland in 1996 under grants from both the Swiss and the Japanese governments. At Hochschule der Künste Bern, he was awarded the soloist diploma for piano under the aegis of Prof. B. Canino, as well as the concert diploma for harpsichord, supervised by D. Börner. He has moreover attended master classes by A. Schiff, P.-L. Aimard, L. Berman, L.F. Tagliavini (organ) and M. Spányi (clavichord). Ooi has appeared as soloist at several festivals, such as La Biennale di Venezia, Musica Viva München, Hannover Biennale, and Festival d' Avignon. He has also played with renowned orchestras and ensembles: Symphonie-Orchester des Bayerischen Rundfunks, Ensemble Intercontemporain at Cité de la musique, Deutsches Kammerorchester Berlin at Philharmonie and Konzerthaus, NHK Symphony Orchestra with Charles Dutoit, Ensemble Asko Amsterdam, etc. In 1993, he won the first prize at the Competition for Modern Music organized by ISCM Japan. He also won at Gaudeamus International Interpreters Competition Rotterdam in 1996, and at Olivier Messiaen International Piano Competition, Paris in 2000. Numerous awards have honoured his activities, such as the Arion Prize (1994), the Aoyama Music Award (1995) for his Japanese premiere of Ligeti's 14 Klavieretüden, the Muramatsu Award (1996) for his recital of the complete works for piano(s) by P. Boulez as well as the prestigious Idemitsu Award (2001).