Air sound emission

Professional Definition

Airborne sound emission is the process of radiating acoustic energy from a specific source (e.g., a machine, device, or vehicle) directly into the surrounding air during its operation.

In physics and environmental engineering, it is crucial to distinguish between two concepts:

• Emission: What the source "produces" and sends to the environment. This is a characteristic feature of the device itself, described by the level of acoustic power (Lw).

• Immission: What reaches the recipient at a given point.

In contrast to the loudness measured by the ear, emission is an objective parameter and theoretically does not depend on the size or finish of the room in which the device is located.

Acoustics in Simple Words

Think of a light bulb and light:

• Emission is the power of the light bulb itself (e.g., 100 Watts). It is a constant characteristic of this bulb. It does not matter whether you screw it into a small tiled bathroom or a large, dark warehouse – the bulb always “produces” the same amount of light at the source.

• How bright the room seems to you (whether the light reflects off white walls or disappears in the darkness of a large hall) is already the effect of the surroundings, equivalent to immission.

Airborne sound emission tells us how loud the “acoustic light bulb” is (e.g., an engine, fan, or washing machine). The manufacturer provides this value on the energy label so that you know you are buying a quiet appliance – regardless of whether you place it in a soundproof kitchen or an empty, concrete basement.

Summary

• Objectivity: Emission is the actual amount of acoustic energy generated by the device.

• Comparability: Allows for accurate comparison of the loudness of two different machines under the same conditions.

• Design: A parameter essential for acousticians when creating noise maps and designing sound insulation in industrial halls.