The interaural level difference is the difference in loudness and frequency distribution between the two ears. As sound travels, its strength dissipates. For example, if you are very close to a loud sound, it will sound loud to you. But if you are some distance from the same loud sound, it will not be as loud.

What are interaural intensity differences?

The IID arises from the fact that, due to the shadowing of the sound wave by the head (head shadow), a sound coming from a source located to one side of the head will have a higher intensity, or be louder, at the ear nearest the sound source. ...

What causes interaural intensity differences?

Intensity differences between the ears can result from two factors: differences in the distance the sound must travel to the two ears and differences in the degree to which the head casts a sound shadow. The greater the sound shadow cast by the head, the greater the level difference between the ears.