Yi's Bell sound and how it relates to temperature? Yi's Bell is an ancient chinese musical instrument that plays different sound frequencies when its heated than when its in room temperature.
My question is Why does that happen? Why does higher body temperature of the bell produces different sound frequencies?
Here is a video of the experiment 
https://youtu.be/id-u9ro50TM
 A: Frequency of bell is inversely proportional to density. As the temperature increases since density decreases frequently increases.
A: According to https://www.a3bs.com/product-manual/U30002_EN.pdf, "This „bell of faith“ was copied from a 2-tone bell discovered in 1978 in the grave of the Chinese marquis Yi from the 5th century BC. It is cast from a newly developed  copper-magnesium alloy and possesses a singular physical characteristic resulting from its special shape and the effect of temperature on oscillation damping." The damping mechanism of manganese-copper alloys is studied in the following article: Metal Science Journal,Volume 2, 1968 - Issue 1, p.129 (https://www.tandfonline.com/doi/abs/10.1179/030634568790443206?journalCode=ymst17). Abstract: "By obtaining a clearer understanding of the mechanism of damping operating in manganese-copper alloys it may be possible either to improve damping properties at elevated temperatures or to select alternative systems with better ancillary properties. Electron-microscope, X-ray, and neutron-diffraction techniques have been used to identify those microstructural features thought to be responsible for the high damping capacity of manganese-copper. Only those compositions that are tetragonal have a high damping capacity. The tetragonality is induced by an antiferromagnetic ordering of manganese ions and the Néel temperature is associated with the drastic fall in damping capacity as the temperature is raised. The structural distortion caused by the cubic → tetragonal transformation creates microtwins and it is the nucleation and growth of these twins that is thought to give rise to the vibrational energy absorption."
