Introduction
Introduction
We don't hear with our ears alone. Hearing also involves the brain.
Auditory processing disorder (APD), sometimes referred as central auditory processing disorder (CAPD), is a general term for hearing disorders in which the ears process sounds normally but the hearing centres and circuits of the brain don't always process incoming information sufficiently quickly or accurately.
Children with APD can hear but they sometimes have trouble with understanding what they hear.
It is estimated that 1 in 20 children have difficulties that affect processing of auditory information in the brain. APD can affect understanding, especially in challenging listening situations such as in the presence of other distracting sound, or when listening to complex information. APD is under-recognised hearing problem that is an underlying cause of learning difficulties in many children. APD is not detected in standard hearing tests but it can be diagnosed with special hearing tests. Most importantly, there are proven helpful treatments.
A number of factors can affect the normal development of auditory processing skills. Causes of APD include hereditary, developmental and birth-related factors, brain injury and neurological disorders. There is also research evidence that suggests that prolonged middle ear disease (e.g ., Glue ear) can result in APD, If hearing is disrupted during important developmental periods in infancy or early childhood.
APD frequently occurs in conjunction with other disorders including in particular dyslexia, autism spectrum disorder (ASD), and developmental language disorder (DLD). APD sometimes co-occurs with attention disorders (ADD and ADHD). Because APD can affect the correct and rapid recognition of phonemes, the sounds of speech, it can be an underlying cause of language, phonological awareness, spelling, and reading problems including dyslexia.
APD is frequently a barrier to meeting academic potential.
Many children with APD will struggle to progress with language and literacy skills, and overall academic progress. Some children with APD may be meeting expectation for their age and year level, yet are not meeting their own potential.
When listening is a challenge, learning is more difficult.
Children with APD may under-achieve in school despite great effort.
The extra effort required for listening often results in children with APD being exhausted at the end of the school day. Because listening is difficult they may also become less attentive, they may become more anxious and frustrated with their learning, or perhaps behaviour becomes a problem. Their communication problems can lead to low confidence and self-esteem, and difficulties with socialisation.
Children with APD often miss, or misunderstand, what is said. This can be because they miss parts of speech that are too fast or too complex, or because hearing against any background noise is especially difficult for them. Children need to develop hearing skills to separate important sounds from other surrounding sounds, such as the teacher’s voice against other children moving and talking. We also need to learn to rapidly and correctly identify all the sounds (phonemes) that make up our language, no matter the voice or speed or accent with which they are spoken, and be able to correctly distinguish between subtly different speech sounds. Children who grow up with APD often have difficulty in always rapidly and correctly identifying every phonemes in spoken language. Children with APD may also have poor skills at detecting nuances of speech denoted by changes in pitch or emphasis which, for example, may indicate emotion or humour or change a statement into a question. See our auditory processing disorder checklist for more information on APD symptoms.
Diagnosis
Diagnosis
APD can only be diagnosed by an audiologist.
Many hearing clinics and audiology services provide general hearing tests and fit hearing aids but not all provide APD services. At SoundSkills APD Clinic we provide an audiology service that specialises in auditory processing disorder diagnosis and auditory processing disorder treatment. We diagnose APD using specialised listening tests (APD tests) that evaluate ability to listen in noise, ability to use both ears together, ability to detect subtle changes in sounds, and auditory memory skills. Most tests of auditory processing require a response from the child. All our auditory processing disorder tests are age appropriate and we consider the limitations associated with other conditions that the child may have.
At SoundSkills we tailor our assessments to meet the individual child’s needs.
So that we can make good decisions on how to best assess for APD and interpret our test results, we include assessment of cognitive ability and language as well as standard hearing tests. We also collect information about auditory skills and listening behaviours through use of questionnaires completed by the child’s teacher and parents.
Age of Diagnosis
A number of factors affect the age at which an APD diagnosis can be made with certainty. As with any aspect of child development, hearing skills mature as children grow and more sophisticated tests become possible. Current tests allow us to make definitive diagnoses from the age of six years old, but considerable information about auditory processing skills can be measured at age five and some APD symptoms can be verified at age four. While a formal APD diagnosis is not usually made under the age of 6 years old, we accept referrals from four years of age since, for children who are clearly experiencing hearing difficulties, it’s best for the child to start age-appropriate interventions as early as possible.
Treatment
Auditory processing disorder is usually very treatable because the hearing dysfunction is in the brain.
With training, the brain is able to learn new skills and develop strengthened or new neural pathways. This is called neuroplasticity.
Because of neuroplasticity, auditory skills can be improved. Some children will develop sufficiently to enable them to no longer be handicapped by APD. But progress depends on a number of factors. The presence of other medical or developmental conditions for example may limit ultimate achievement. Cognitive and language development must also be taken into account when testing and interpreting results of an APD assessment and when predicting effectiveness of hearing treatments.
There are three main components to treatment of APD: auditory training to correct any one-sided hearing weakness (amblyaudia) and improve hearing ability; fitting of assistive hearing technology to assist hearing and ultimately improve hearing abilities over time; and language therapy including phonological awareness training.
APD treatment requires a team approach.
Successful intervention and management of APD occurs when a team of professionals work together to provide treatment and support. At SoundSkills APD Clinic we provide a specialist team of audiologists, speech language therapist, and Education Advisers to contribute to treatment. Our Education Advisers also go into a child’s school and work with the child, teacher and parents. We also collaborate as required with other specialist services outside of SoundSkills such as educational psychologists, occupational therapists, ENT Specialists and teachers.
The first priority with an auditory disorder is to help the person hear better.
Treating the auditory disorder may include auditory training therapy and/or fitting remote microphone hearing aid systems.
Auditory Skills Training
Some auditory processing deficits can be improved by auditory training. This can be in-clinic therapy or at home training and includes deficit-specific treatment such as ARIA (Auditory Rehabilitation for Interaural Asymmetry) therapy or SoundSkills AudiTrain software for amblyaudia, and computer-based programmes. Learning a musical instrument (including singing coaching) is also beneficial for auditory processing skills.
Remote Microphone Hearing Aid (RMHA) Systems
RMHA systems consist of small hearing aids worn by the child and a small transmitter microphone worn by the speaker (for example; parent, teacher, coach, friend). The remote microphone transmits the speaker’s voice direct into the hearing aids. RMHA systems (previously referred to as FM systems) have a double effect. RMHA systems assist children to hear and treat the hearing problem.
How do RMHA systems assist children with APD?
RMHA systems greatly improve the ability of children with APD to hear, learn and participate in multiple life situations. Benefits that have been verified in research studies include improved classroom attention and participation, academic achievement, phonological awareness, reading and social development. Improvements in confidence and self-esteem are seen, and children are less fatigued after school.
Hearing in school
Classrooms can be difficult listening environments. With the move to large innovative learning environments (ILEs) with many children and multiple teachers in the same acoustic space, children are faced with special hearing challenges including an increase in classroom noise, longer listening distances and multiple learning positions.. Current studies show that the average classroom noise level is 69 decibels (dBA) equivalent to the sound of a vacuum cleaner in a house or a road-side with traffic going by. Higher average levels have been recorded in some in ILEs.
RMHA systems assist children to hear and learn
by amplifying the teacher’s voice to a level that is clear, safe and consistent no matter where the child is, or what the background noise level is like.
How do RMHA systems treat APD?
The mild amplification provided by remote microphone hearing aid systems stimulates auditory pathways and centres in the brain. Through a process called synaptogenesis new connections can be made and pathways strengthened. Research shows multiple hearing benefits, seen as improved hearing skills (measured when not wearing RMHA systems), over time in children with APD or dyslexia as a result of having worn RMHA systems. Some of these beneficial neuroplastic changes are observable in recordings of brain waves in response to sounds. This therapeutic effect of using RMHA systems means that children may not need hearing assistance long term. On average two to three years of use is common but individual cases vary markedly.
Treating phonological and language problems
Children with APD often have deficient phonemic perception, that is, they may not recognise or be able to differentiate all of the sounds of language quickly and correctly under all listening conditions. This leads to weaknesses in phonological awareness, the ability to recognise and manipulate the sounds which make up spoken language.Poor phonological awareness often underlies poor spelling, poor vocabulary, and reading and language disorders. A speech language therapist can assess the areas of deficiency and implement a therapy programme to address them all. Phonological and language therapy doe not directly address the underlying hearing problem as do auditory training therapy and the use of remote microphone hearing aid systems. But they are nonetheless critical in addressing the consequences of the poor hearing and as such are an integral part of the management of APD.
School Guidance
For children, optimising the learning environment is critical. When remote microphone hearing aid systems are trialled in school it is important to have an expert involved at the school to assist the child, teacher and parents with the trial and to ensure the hearing system is used optimally. The SoundSkills team includes Education Advisers, experienced in special education, who work on site with the school’s Special Education Needs Coordinator (SENCO), the teacher and any other education staff who are involved, as well as with the child and parents. They facilitate introduction of remote microphone hearing aid systems, help set up the trial, carry out classroom observation of the child to ascertain the difficulties the child encounters, provides guidance on communication and teaching strategy, and assist with Individual Education Plans, goal setting, monitoring and funding applications.
Auditory Software
There are many auditory training software apps and programs promoted as home-based treatments for APD but not all have been proven effective in scientific trials. Specific auditory software can be effective when chosen as part of a comprehensive treatment plan. Follow your audiologist’s advice on which auditory training programmes are both evidence-based and appropriate for your child.
Treatments not supported by scientific evidence
Some alternative treatments promoted for APD lack a plausible scientific basis and/or a solid body of peer-reviewed evidence of efficacy published in reputable scientific journals. In particular professional audiology and speech-language organisations warn that franchised systems based on listening to processed music, sometimes utilising bone conduction rather than air conduction, should not be recommended or used by their members. In the same way that watching sport doesn’t improve fitness, research shows that passive listening to music does not improve auditory processing skills. On the other hand active engagement in learning music is excellent for auditory skills.
There is evidence however that listening to mildly amplified speech through audiobook listening is beneficial for children. We recommend books that engage and maintain a child’s attention be used so that the child is actively engaged in the listening process.
Funding
Funding
The Ministry of Health provides free hearing aids for children with other causes of hearing loss, but specifically excludes hearing loss due to APD. In a limited proportion of cases the Ministry of Education provides remote microphone hearing aid (RMHA) systems for high needs school age children diagnosed with APD. In order to be accepted for a trial the child must meet certain restricted criteria. SoundSkills assists clients to determine whether they might qualify for a Ministry of Education assistive hearing technology trial.
The Ministry of Education fitting service is variable across New Zealand; some children are provided equipment directly from their school, whereas some other children have their hearing systems fitted by an audiologist.
In accordance with the New Zealand Guidelines on Auditory Processing Disorder we recommend that RMHA systems are fitted by an audiologist to ensure that the physical fit and the sound are set correctly for the individual child.
SoundSkills can provide a fitting service for Ministry of Education funded RMHA systems on request. Fitting by a professional avoids such problems as incorrect volume/gain settings, unbalanced settings between left and right receivers, problems with physical fit, and fitting when there are contraindications that can only be identified through looking in the ear using an otoscope or microscope.
In the absence of public funding parents can purchase RMHA systems privately from SoundSkills. As a lower cost option manufacturer refurbished systems are sometimes available. SoundSkills offers a comprehensive service involving selection of a suitable solution, audiological fitting, a trial period of several weeks, and assistance throughout the trial period from one of our Education Advisers who will work with the family and school to carry out an effective trial with classroom observation and measurable goals and assist in reaching a decision on whether to proceed with the selected hearing equipment.
Children with APD who also have a hearing loss evident in a standard hearing test may be eligible for the Hearing Aid Funding Scheme (HAFS) provided by the Ministry of Health. The HAFS covers the cost of hearing aids but not the cost of the fitting service.
Accident Compensation Corporation (ACC)
When APD is associated with injury, ACC may cover the cost of assessment and recommended treatment including RMHA systems, auditory training and language therapy.