heliõhu

Heliõhu is an Estonian term describing the propagation of sound waves through the Earth's atmosphere. In practice, it denotes the study of how atmospheric conditions affect sound transmission, a topic that sits at the intersection of acoustics and meteorology. The term is used in Estonian-language texts as a concise reference to air-mediated acoustical phenomena.

Sound travels as mechanical waves in air, and its speed depends mainly on temperature: as air heats, molecules move faster, and the speed of sound increases roughly with the square root of temperature. Humidity and pressure also influence propagation, but to a smaller degree. Attenuation arises from molecular absorption, scattering by aerosols, and turbulence. Wind and temperature gradients can refract sound, bending paths toward or away from distant observers.

Modeling heliõhu is important for outdoor sound reinforcement, environmental noise assessment, urban planning, and wildlife studies. Accurate predictions require atmospheric profiles and sometimes numerical models that couple acoustics with meteorology. Practical applications include predicting how traffic noise travels from a highway to nearby neighborhoods or how a concert’s sound disperses across an open square under varying weather conditions.

Relation to other terms: heliõhu is a wording used in Estonian-language sources for concepts commonly described as sound propagation in air or aeroacoustics in English. The name itself combines heli (sound) and õhk (air) in genitive form, reflecting its focus on how air mediates acoustic waves.