The Soundwave Hunter’s Guide to Acoustic Forensics

Leng Shiyan is a piano tuner with pitch accuracy to within one ten-thousandth of a note. Her ears can pick up “historical sound traces” imperceptible to ordinary people: faint sonic impressions left behind in the resonance of objects. The vibrations of piano keys record the players’ shifting emotions, while the scrape of a doorknob holds unique information about whoever touched it. As she tunes a battered secondhand Steinway grand, the sound of its hammers striking the strings is joined by distant, indistinct gunshots and desperate cries for help. This is no science fiction, but the real past revealed by Leng Shiyan’s extraordinary hearing. Together with Jiang Lin, a meticulous and practical chief of criminal forensics, she establishes a “database of object soundprints” and explores the limits of sound as forensic evidence. Metal objects retain traces for three years, while wooden ones preserve them for only six months. Her ability is far from infallible. From identifying a serial killer through the distinctive “wail” of metal fatigue in a murder weapon to ultimately helping bring about the Standard for the Collection of Forensic Acoustic Evidence, Leng Shiyan uses ears that can hear the world’s “heartbeat” not only to tune piano strings, but also to bring a new dimension of precision to forensic justice, demonstrating the irreplaceable value of a piano tuner in the courtroom.