Improvisers Xavier Charles and Bertrand Gauguet have been playing duets since 2013. They produce frequency landscapes that change slowly and thus move the listener towards a contemplative listening. With the multiple sounds of the clarinet and the saxophone, other inflated spaces based on breaths arise...  Spectre, which was released on CD in early May 2020 at Akousis Records, contains six pieces exploring multi-phonic spaces on the clarinet and alto saxophone (Phonomnèse 1, Phonomnèse 2 and Phonomnèse 3), spaces linked to breath (Point fantôme) and the sonic landscapes developed by the amplification (Étendue 1 and Étendue 2). 

The two recording stages made it possible to experiment with particular sound recordings as with Alexis Derouet in December 2017 in Césaré for recordings with a single mono microphone or even more complex devices with microphones differently positioned in the studio. The two musicians could thus choose to keep a static position or to be mobile in space. At PiedNu in March 2015, research focused with Emmanuel Lalande on signal amplification and distortion with the intention of producing expanses. Spectre's music is constructed like a mirror that would reflect multi- phonetic acoustic pieces on one side and reflect amplified pieces on the other. The Phantom Point remains a vanishing point between these two sonic spaces.