Average power spectral density of bass-oriented (blue, n = 11) and treble-oriented (red, n = 7) kemenche samples. Each instrument was played by an experienced performer executing a standardised bowing pattern (open strings, mezzo-forte, 3 repetitions per instrument). Recordings were made with a Neumann TLM 170R cardioid condenser microphone at 50 cm distance, 45° off-axis, in an acoustically treated room (RT₆₀ ≈ 0.3 s at 1 kHz; background noise < 30 dB(A)). Power spectral density was computed using Welch’s method (Hanning window, 50% overlap, 4096-point FFT, 44.1 kHz sampling rate), normalised by total energy (0–5 kHz), and averaged within each group. Shaded bands represent ±1 standard deviation across instruments within each group. The grey shaded region marks the high-frequency analysis band (2–4 kHz). Treble-oriented instruments demonstrate 28.3 ± 6.1% (bootstrap 95% CI) greater high-frequency energy in the 2–4 kHz band.