This Swiss percussionist has been quietly carving out a very cool and unique niche for himself over the last decade, as he continually finds unusual conceptual scenarios to combine with his virtuosic playing. I greatly enjoyed 2021's aptly titled Locked Grooves, but had not yet delved too deeply into his earlier work, so I had missed the first installment of Hidden Tracks: 2017's Basel – Genève. For that album, Sartorius brought his drumsticks along for a 10-day, 270km hike along Switzerland's Jura Ridgeway Trail and recorded improvised beats on whatever intriguing sound sources he encountered (trees, empty silos, corn stalks, etc.). On this latest installment, his journey is now vertical, as Sartorius kept a similar beat diary as he climbed from the Italian village of Domodossola "to the peak of Weissmies (4017m above sea level) in the Swiss Valais." In theory, that upped the game considerably constraint-wise, as Sartorius gradually leaves behind both humanity and trees in his ascent, but that comparative dearth of available sound sources was no match for his resourceful inventiveness.
The album is presented as a series of eight pieces that mirror Sartorius's ascent in 500 meter intervals, so the first piece (272m_↗_500m) is built from sounds recorded in Domodossola and the last piece is assembled entirely from sounds collected near the mountain summit. Notably, Sartorius was joined by videographer Stephan Hermann and his footage makes for a wonderfully illustrative guide to the shifting terrain that the duo encountered. It also helpfully illuminates how Sartorius was able to make these recordings, which is something that initially baffled me, as some of these pieces seemed impossibly complex to perform in real-time and Julian made a point of stating that "no electronic effects or sound processing were used." That claim is indeed factual, but there was some post-recording assembly involved: Sartorius recorded multiple tracks (usually played one-handed while the other hand wielded a microphone), then assembled layered beatscapes from the sounds collected at each elevation. That essentially means that a kick drum pattern might have been recorded with one pile of rocks, but the rest of the beat may have been recorded using a completely different pile of rocks. That said, that finished recordings make for a very impressive audio illusion, as it often sounds like Julian's drumming is taking place in real-time and intuitively interacting with non-percussive field recordings of cars, birds, planes, radios, cows, and sprinklers.