Why do hot and cold water sound different when poured?

Abstract

Empirical studies have demonstrated that humans possess the remarkable capacity to distinguish whether a glass of water is hot or cold solely by the sound of pouring it. However, the underlying physical mechanisms governing the disparities in the acoustic signatures of hot versus cold water remain to be deciphered. In this paper, we conducted a series of experiments to extract the intrinsic features of pouring sounds at contrasting temperatures. The results of our spectral analysis revealed that the sound of pouring hot water exhibited more pronounced low-frequency components and diminished high-frequency components relative to cold water. High-speed photographic evidence elucidated that pouring hot water could generate larger air bubbles in greater abundance. We conjecture that the Minnaert resonance arising from these larger entrained bubbles in hot water produces a lower-frequency acoustic signature, thereby constituting the foundational mechanistic explanation for the auditory distinction between pouring hot and cold water.