concept A speed which waves propagate in air mostly depends on temperature. When the temperature of air is higher, the speed is fast. in opposite when the temperature is low, the speed is slow. Temperature is a physical property of matter which is proportional to the mean kinetic energy of its particles. It’s derived from the mean energy of random motions of air particles. ‘heat’ is an energy which is diverged to low temperature from high. Heat is not any material, it’s just energy.
On the other hand, 'sound' is physical phenomena which are waves propagate in medium as air -i.e. a periodical motion of the medium. Generally vibration which we can hear is called as sound. In this sense, sound is macroscopic motions of air.
Sound wave changes its speed by heat, and the acoustic also changes. The relationship between heat and sound, I’m thinking that this is an important crossover point of microscopic view and macroscopic view concern with air condition.
A beat arise by a difference between two frequencies. superposing a constant sound in a space temperature and a changing sound in the different thermal state. Through the beat and its change, we can observe 'thermal' as microscopic air molecular motions which are random. I think the sound presents a shape of thermal world, it’s essential, pure and disorder, where we live.
In this work, I treat a concept of thermal issue such as above.

Concerning a sound by using Liebig condenser;
Liebig condenser has two vessels. One is straight tube. The other one surrounds the straight tube. The sound is produced as air column resonances by the straight tube. The other tube is filled by water and has a nichrome heater in order to change an air temperature of the straight tube.