The team that arranged this bizarre musical cover, including Uriel Seidel, sez:
Bats produce sounds that are not audible to human ears. First these ultrasounds were digitally reduced to frequencies that are audible. Then the different batsounds were assigned different keys on a keyboard. On this keyboard – the only real Bat-Organ – Ulrich Seidel played the Batman Theme (Neal Hefti, 1966). The video clip was compiled by Sándor Seuntjens using footage from Batman (film, 1966), Batman (animated television series, 1992-95), and National Geographic.