What is the minimum intensity of sound required for the human ear to perceive a sound?

The minimum intensity of sound required for the human ear to perceive a sound is known as the threshold of hearing, which is approximately 10^-12 watts per square meter. This value represents the faintest sound that an average human ear can detect, making it a crucial reference point in acoustics and sound measurement.

Understanding this concept is essential for grasping how sound intensity is measured in relation to human perception. The logarithmic scale of sound intensity conveys that the human ear is capable of experiencing a wide range of sound pressures, starting from this very low threshold. This threshold is why sound intensity is often expressed in terms of decibels, where values are calculated based on a logarithmic scale of powers of ten relative to this baseline.

The other given values—120 watts/square meters, 0.001 watts/square meters, and 0.1 watts/square meters—are significantly higher than the threshold of hearing and do not accurately reflect the minimum intensity needed for perception by the human ear. Knowing the threshold helps in understanding sound levels we encounter daily and assists in various applications, from hearing aids to audio engineering.