Auditory Processing Disorder (APD) is a type of learning difficulty. It means that your brain has a hard time understanding and interpreting the things you hear. It may cause you to have trouble hearing subtle differences in words or sounds. For example, you may find it difficult to understand a person's voice if they're talking too quickly, if there is a lot of background noise, or if they are talking too softly. APD can also make it hard to concentrate on the things you hear, like a teacher's lecture. People with APD may also find it hard to remember what they hear.