Homomorphic filtering for extracting Javanese Gong wave signals

Abstract

The Gong is a unique percussion instrument of Gamelan because of its wave-like sounds after being struck immediately. These special sounds correspond to the characteristics of each gong which is originated from different places. This phenomenon might raises from the primary beat of the partials and or mismatched overtone frequencies. However, there has been a lack of studies that rigorously locate the beat and/or a set of beat frequencies the better understand the perceptible beat. This study attempts to trace the beat-showing occurrences in the quefrency domain employing a set of homomorphic operations. First, acoustic measurement was conducted and further analyzed using homomorphic operations to obtain its cepstral profile. The rapidly-varying frequency part was filtered out to show the location of a set of beats. The cepstrum also show a prominent peak at 0.01 s, which corresponds to the harmonicity of 47.6 Hz. This is in agreement with the measured fundamental frequency of Gong Kempul.