Resonances is the first album by Ensemble Supersonus, the quintet led by the Italian nyckelharpa player Marco Ambrosini. Its sound comes from an unusual set of instruments: the Swedish keyed fiddle, Estonian kannel, harp, jew's harp, harpsichord and square piano, topped by the overtone singing of Anna-Maria Hefele. The programme sets Biber, Frescobaldi, Froberger and Hildegard von Bingen beside Swedish folk music, Ottoman court music and new pieces by the members.

Ambrosini, born in Forlì and a co-founder of Oni Wytars, was first heard on ECM on Rolf Lislevand's Nuove Musiche. The current line-up formed in 2014 around a shared interest in linking archaic styles with Baroque and other early music. Alongside Ambrosini and Hefele, it includes Anna-Liisa Eller on kannel, Wolf Janscha on jew's harp and Eva-Maria Rusche on harpsichord and square piano. The album was recorded in November 2015 at the Auditorio Stelio Molo RSI in Lugano, in collaboration with RSI Rete Due, with Lara Persia as engineer and Manfred Eicher as producer.

Ambrosini opens alone with his Fuga Xylocopae, before the ensemble turns to the first of Biber's Rosary Sonatas, where Hefele's overtones float above the plucked harpsichord. Hildegard's O Antiqui Sancti is given a still, hovering setting, while Rusche's Erimal Nopu is fast and rhythmically driven. The Hicaz Hümâyun Saz Semâisi by the eighteenth-century composer Veli Dede brings in the Ottoman modal tradition, with a searching melodic line. Nearby sit a Swedish Polska, a Froberger toccata played on square piano, and three pieces by Janscha, among them the closing Ritus. Hefele's own 2 Four 8 is a dense web of overtones.

Reviewers stressed how far this lies from the usual instruments of jazz. In London Jazz News in 2019, Peter Bacon wrote that "it is the vocalist in the group who creates the most extraordinary sound of all". Felipe Freitas of Jazz Trail found them "often blurring the line between written material and improvisation", well away from the main traits of jazz. In Stereoplay, Ralf Dombrowski praised the recording itself, in which every instrument can be heard in its full detail.

This is the CD edition, ECM 2497, first released on 21 June 2019.