Update: March 13, 2021
We only discovered the portable drum chime in 2020, following the reassembly of the western enclosure wall of the Banteay Chhmar temple. It was first reported to us by Phalika Ngin. It is unknown elsewhere in Angkorian iconography. The bas-relief is damaged, but originally the instrument had nine drums, like the gong chime.
The drum chime is part of a standard set of instruments for the Bayon period, namely, from left to right:
The only countries in which the drum chime remains is Myanmar and Thailand where it is respectively named pat-waìng ပတ်ဝိုင်း and poeng mang เปิงมาง. Contrary to the instrument of Banteay Chhmar, it is not a portable but a fixed instrument.