Portland Auditory Processing Diagnostics

Before we audiologists became more aware of APD and its impacts, people were often told that children with APD as children would "just grow out of it." Nope. Turns out people with APD as children often get better at finding ways around their hearing difficulty, but they still have problems in work environments where it is necessary to carry out instructions in noisy environments, understand multiple simultaneous speakers in the workplace, understand instructions in the midst of machine noise, carry on a conversation in a cubicle surrounded by a hundred other people in near-by cubicles also on the phone talking to people, etc. We expect adults to understand oral directions the first time, to be able to separate the important speech from unimportant speech, to concentrate on paperwork while someone near them is talking, or listen to lectures or meetings and simultaneously take notes. APD makes these tasks hard.

People who have APD often had a hard time learning to read when in school. Either they learned very late (eight years and up) or they learned to "sight read" because phonics was very hard for them. When the ability to hear fine auditory differences that phonics requires is disrupted, learning to read becomes difficult. We know there is a genetic component to this, but poor hearing as a young child is also a factor. People with APD often have a history of difficulty learning to talk also. Children start out only approximating the speech they hear, but over time they improve their speech ability and become more and more understandable ("intelligible"). Parents usually figure out what young children are saying, but toddlers usually go through stages of being understandable by strangers. Strangers should be able to understand most of what a three-year-old says even though the three-year-old is still using common mis-articulations. After that, we consider that there is a delay in speech, and probably language development too.

People often wonder what causes APD. That is hard to pin down. But we do know that people who have a lot of ear infections ("otitis media") tend to have difficulty with APD tasks. The hypothesis is that ear infections at a young age, especially when children are just learning language, altered their hearing because of the fluid in the middle ear that goes along with ear infections, and the two ears often have different amounts of alteration. Almost always otitis media resolves. It is common in babies and young children, but tends to become rare after the age of eight years. Otitis media usually disrupts the Eustachian tube's ability to equalize pressure (and that is also a way that fluid is expelled from the middle ear) because of swelling. Some people don't have ear infections, but the muscle involved in the opening of the Eustachian tube doesn't work, and the result is a build-up of fluid in the middle ear just like what happens with ear infections, causing a mild hearing loss. Ventilation tubes are placed in the eardrum by physicians to keep the pressure on either side of the eardrum equal (which is essential to good hearing). We don't know exactly why, but that disruption, especially at an early age, is correlated with APD later on.

Hearing in noise is a complex auditory task because listeners usually want to pay attention to one sound source (like speech) in a situation in which there are multiple sound sources happening simultaneously. Noise could be environmental, such as: road noise when riding in a car, noisy air conditioning units, traffic noise when walking outside. Often the "noise" in a situation is actually a second conversation going on, such as someone listening to a radio at the same time they listen to someone speaking to them. Comprehending speech in a restaurant or other environment in which many different conversations are happing at the same time is usually very difficult for people with APD. Clients tell me that they can't understand what a waitperson is saying when they try to order, can't understand the conversation around the table, or that all of the speech happening simultaneously in the restaurant just seems like a big blur, and none of it makes sense. Listening to a conversation while the radio is playing in a car is another speech-in-noise environment. Even following a lecturer when people around the listener are whispering or chatting can be a difficulty with understanding speech-in-noise.