The Pipa: A Case Study of the Classic Chinese Lute – An Analysis of its Acoustic Characteristics

Abstract

The Chinese pipa, a lute with a large number of frets, is known for its rich timbral and expressive capabilities. The sound signals were recorded in real time using a PC-based USB oscilloscope and associated data recorder. The digital storage oscilloscope program enabled voltage-based triggering and Fast Fourier Transform (FFT) analysis. While the heard notes according to the 12-Tone Equal Temperament (TET) tuning are A3, E3, D3, and A2, the digital oscilloscope recorded the harmonic frequency for open strings 1, 2, 3, and 4 as 880 Hz (A5=880.00), 656 Hz (E5=659.26), 586 Hz (D5=587.33), and 439 Hz (A4=440.00). Because of the occurrence where the listener claimed to recognize the note A2 while they heard A4, the measured frequencies do not match perceived notes. This is a well-known missing fundamental phenomenon. The pipa produces a complex overtone structure that is aligned with integer multiples of an implied fundamental over all strings and fret positions, according to the harmonic analysis. A3, A♯3/B♭3, B3, C4, C♯4, D4, D♯4, E4, F4, F♯4, G4, G♯4, A4, A♯4/B♭4, B4, C5, C♯5, D5, D♯5, E5, F5, F♯5, G5, G♯5, A5, A♯5/B♭5, B5, C6, C♯6, D6, E6 are the running notes for open string 1 and fret 1 through 30, which in semitone intervals consistent with modern equal temperament. Based on pure intervals, the pipa's 30 frets are widely separated and sonically pure.