Interaural Level Difference

The difference in sound pressure level (loudness) between the two ears, used by the auditory system to localize sound sources. Sounds coming from the right are louder in the right ear due to the head creating an acoustic shadow. ILD is most effective for localizing high-frequency sounds (above 1500 Hz) and is a key parameter in spatial audio systems. In accessibility applications, ILD is used in sonification and audio interfaces to convey horizontal position information—for example, making sounds louder in the left ear to indicate elements on the left side of a display or tactile graphic.