What happens to the sound pressure level as the distance from the source increases in an open environment?

In an open environment, the sound pressure level decreases as the distance from the source increases. This decrease is characterized by what is known as the inverse square law, which states that the intensity of sound (and thus the sound pressure level) diminishes proportionally to the square of the distance from the source.

As sound waves propagate from a point source, they spread out in a spherical manner. The energy carried by these sound waves is distributed over an increasingly larger area as the distance increases. Consequently, the pressure of the sound waves—measured in decibels—drops because there is less energy per unit area at greater distances from the source.

In practical applications, this means that for every doubling of the distance from a sound source, you can expect a decrease of approximately 6 dB in sound pressure level. Therefore, as one moves further away from the sound source in an open environment, the perception of that sound becomes quieter, demonstrating a clear decrease in sound pressure level.