The phrase "cracking sound" refers to a sharp and loud noise that an object makes when it breaks or when pressure is applied to it, similar to the sound of snapping fingers or breaking a stick. Full definition
This could be because of low - quality ear - piece, which causes cracking sound if a person on the other end talks loudly. (techtree.com)
So, using mathematical models, Suja and his colleague Abdul Barakat found that just a partial collapse of the bubbles could cause cracking sounds of the same degree, which might explain why the 2015 researchers still saw bubbles after the crack. (scientificamerican.com)
The center storage makes an odd creaking / cracking sound when I put my elbow on it. (autolist.com)