**1.4 Auditory training in central auditory processing disorder**

It is well established that listeners with CAPD exhibit diverse behaviors such as poor listening skills, difficulty learning through the auditory modality, difficulty following auditory instructions, difficulty in understanding when there is background noise, requesting information to be repeated, poor auditory attention, easily distracted, deficits with phonological awareness and phonic skills, weak auditory memory, delayed response to verbal stimuli, and difficulty with spelling, reading, and learning [49].

A diagnosis of impaired central auditory processing is done by applying a battery of behavioral and electrophysiological procedures. The results provide information about the physiological mechanisms in the auditory system and a profile of abilities that are altered and those that are preserved. Based on this diagnostic information, rehabilitation should start as soon as possible in order to minimize the effects of CAPD on language development. One strategy is the use of auditory training (AT), defined as the set of (acoustic) conditions and/or tasks designed to activate auditory and related systems such that neural connections and the associated auditory behavior is improved [50].

The general aim of AT when applied to individuals with CAPD is to improve auditory skills such as sound localization and lateralization, auditory discrimination, auditory pattern recognition, temporal aspects of audition, and auditory

**57**

*Neuroplasticity and the Auditory System DOI: http://dx.doi.org/10.5772/intechopen.90085*

positively effective outcomes [50].

in the child's overall care [52] (**Figure 3**).

tive and metalinguistic activities [52, 53].

appropriate for the patient.

and binaural listening [51, 54].

i.Preferential seating

iii.Clear language

ii.Addition of visual cues

The AT program should follow some important principles:

• It should include diverse tasks to maintain motivation.

ological, and questionnaire-based information [50, 52].

• It should be gradual in difficulty over time.

bring many benefits to learning. Options may include:

iv.Making frequent checks for understanding

discrimination against competing acoustic signals [51]. Formal and informal AT procedures are conducted by audiologists in the clinical environment. The difference between them is that formal training needs to be acoustically controlled, with a strict control over the stimulus generation and presentation. The combination of formal and informal AT procedures offers a flexible approach which presents

The management of CAPD requires a multidisciplinary team, since the pathology commonly appears with other disorders (attention deficit/hyperactivity disorder), learning and language disabilities, or dyslexia. The multidisciplinary team members are often speech-language pathologists, psychologists, neuropsychologists, neuropediatric specialists, teachers and parents, or other specialists involved

The therapy to enhance auditory skills should be evidence-based, individualized, and segmented into bottom-up and top-down treatments. A bottom-up approach is based on the premise that difficulties in central auditory processing (CAP) lead to impaired auditory perception, language, reading, and communication. The objective of the bottom-up therapy is to improve speech perception. The top-down approach includes auditory cohesion, auditory attention, and metacogni-

• It should be frequent, challenging, and motivating, using age and language

• It should employ a follow-up on acquired responses (achieving response rates

• It should use monitoring and feedback based on psychophysical, electrophysi-

>70% is an indication that the task needs to be more demanding).

The results obtained in the diagnostic battery will guide the therapeutic planning, which should include tasks aimed at discriminating sound intensity, frequency, and duration; phoneme discrimination; time perception discrimination; temporal ordering and sequencing; pattern recognition, location, and lateralization; and recognition of auditory information in the presence of competitive signals. Other aspects may include study of interhemispheric information transfer

In addition, modifications are important depending on the environment. To improve access to auditory information outside the therapy room, teachers and parents also need to help with CAPD treatment strategies. Simple changes may

### *Neuroplasticity and the Auditory System DOI: http://dx.doi.org/10.5772/intechopen.90085*

*The Human Auditory System - Basic Features and Updates on Audiological Diagnosis and Therapy*

decreased sensitivity to particular frequencies [40]. In addition, the extra noise can mask speech sounds, thereby impoverishing the auditory experience. As a result, infants can become more sensitive to noise and focus their attention on this type of sound stimulus instead of ignoring it and focusing on speech [41]. Among preterm infants there is a high rate of impairment of hearing, language, and attention; on the other hand, a home environment rich in post-NICU auditory and linguistic stimuli favors auditory neuroplasticity, meaning that premature infants then have a

One way to observe plasticity in the auditory system is by monitoring patients undergoing cochlear implantation. Even after a period of auditory deprivation due to hearing loss, it is possible for the brain's auditory system to reorganize and develop better hearing abilities. Research on children implanted at the age of 3, 5, and 7 years has demonstrated that cortical auditory development can be mixed, with some children presenting cortical auditory evoked potential responses (notably P1) within normal limits, while others do not seem to achieve normal central auditory maturity. These findings are consistent with positron emission tomography (PET) imaging tests performed before and after cochlear implantation. It appears that 3.5 years of age is the end of the sensitive period for cochlear implantation in children with congenital deafness; this age is approximately when the observed exponential increase in synaptic density ends and begins to decrease [35]. Beyond 7 years of age, neuroplasticity in the central auditory system is significantly reduced; if new sounds are introduced after this time, the auditory cortex is unable to process auditory information normally [38, 43]. Research on the development of speech and language skills in children has indicated significantly better outcomes in

Neuroplasticity can be observed in individuals with central auditory processing disorder (CAPD) who have undergone auditory training. Training is a therapeutic procedure involving auditory stimulation that leads to reorganization (remapping) of the cortex and brainstem, improving synaptic efficiency and increasing neural density. These neurophysiological changes, reflected on behavioral changes, have

It is well established that listeners with CAPD exhibit diverse behaviors such as poor listening skills, difficulty learning through the auditory modality, difficulty following auditory instructions, difficulty in understanding when there is background noise, requesting information to be repeated, poor auditory attention, easily distracted, deficits with phonological awareness and phonic skills, weak auditory memory, delayed response to verbal stimuli, and difficulty with spelling, reading,

A diagnosis of impaired central auditory processing is done by applying a battery of behavioral and electrophysiological procedures. The results provide information about the physiological mechanisms in the auditory system and a profile of abilities that are altered and those that are preserved. Based on this diagnostic information, rehabilitation should start as soon as possible in order to minimize the effects of CAPD on language development. One strategy is the use of auditory training (AT), defined as the set of (acoustic) conditions and/or tasks designed to activate auditory and related systems such that neural connections and the associ-

The general aim of AT when applied to individuals with CAPD is to improve auditory skills such as sound localization and lateralization, auditory discrimination, auditory pattern recognition, temporal aspects of audition, and auditory

good chance of developing normal speech, language, and learning [42].

those who received cochlear implants at younger ages [44, 45].

encouraged the use of this rehabilitation strategy [46–48].

**1.4 Auditory training in central auditory processing disorder**

**56**

and learning [49].

ated auditory behavior is improved [50].

discrimination against competing acoustic signals [51]. Formal and informal AT procedures are conducted by audiologists in the clinical environment. The difference between them is that formal training needs to be acoustically controlled, with a strict control over the stimulus generation and presentation. The combination of formal and informal AT procedures offers a flexible approach which presents positively effective outcomes [50].

The management of CAPD requires a multidisciplinary team, since the pathology commonly appears with other disorders (attention deficit/hyperactivity disorder), learning and language disabilities, or dyslexia. The multidisciplinary team members are often speech-language pathologists, psychologists, neuropsychologists, neuropediatric specialists, teachers and parents, or other specialists involved in the child's overall care [52] (**Figure 3**).

The therapy to enhance auditory skills should be evidence-based, individualized, and segmented into bottom-up and top-down treatments. A bottom-up approach is based on the premise that difficulties in central auditory processing (CAP) lead to impaired auditory perception, language, reading, and communication. The objective of the bottom-up therapy is to improve speech perception. The top-down approach includes auditory cohesion, auditory attention, and metacognitive and metalinguistic activities [52, 53].

The AT program should follow some important principles:


The results obtained in the diagnostic battery will guide the therapeutic planning, which should include tasks aimed at discriminating sound intensity, frequency, and duration; phoneme discrimination; time perception discrimination; temporal ordering and sequencing; pattern recognition, location, and lateralization; and recognition of auditory information in the presence of competitive signals. Other aspects may include study of interhemispheric information transfer and binaural listening [51, 54].

In addition, modifications are important depending on the environment. To improve access to auditory information outside the therapy room, teachers and parents also need to help with CAPD treatment strategies. Simple changes may bring many benefits to learning. Options may include:


Monitoring progress of the patient is important since it allows the therapist to measure the appropriateness of the AT program and provides a basis for feedback to the patient and parents [50]. Ideally, three types of monitoring should be employed to measure auditory changes: psychophysical, electrophysiological, and questionnaires. These measures should be obtained before and after hearing training. Several questionnaires are available and can be answered by the patient and/or individuals interacting with him or her, such as parents, teachers, and other professionals.

Several questionnaires are described in the literature, such as the Children's Auditory Performance Scale (CHAPS) [55, 56], Screening Instrument for Targeting Educational Risk (SIFTER) [56, 57], Children's Home Inventory of Listening Difficulties (CHILD) [58], and the Scale of Auditory Behaviors (SAB) [58].

A large number of studies provide definitive evidence for the plasticity of the auditory system evidenced by behavioral changes in both animals [59–61] and in humans [62–68]. A recent study by Donadon et al. [69], whose objective was to investigate auditory training in children and adolescents suffering from otitis media

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*Neuroplasticity and the Auditory System DOI: http://dx.doi.org/10.5772/intechopen.90085*

**2. Conclusion**

disorders.

**Abbreviations**

with a documented history of bilateral ventilation tube insertion, highlighted some aspects of auditory neuroplasticity. According to the data from the study, the participants were randomly divided into two groups: (i) auditory training and (ii) visual training. In the behavioral tests during the pre-intervention evaluation, no statistical differences were detected. However, after the auditory training program, there was an improvement in the subjects' performance for auditory abilities. In addition, comparing the two types of intervention (visual vs. auditory), the behavioral tests revealed better responses to the post-intervention auditory training. The results, assessed through behavioral tests on subjects with a history of bilateral otitis media, suggest that auditory training provided beneficial gains for all auditory abilities.

The central auditory nervous system is responsible for the processing of auditory information. It is highly complex and plastic, being able to reorganize itself in response to auditory stimulation. Auditory training promotes behavioral and electrophysiological changes due to the neurophysiology of the brain's plasticity. The latter enables the positive performance of the auditory training, which is an important rehabilitation strategy for individuals with central auditory processing

critical period the time during which the neural system is unable to adapt

Wada test a test for determining the dominant hemisphere for speech

AD/HD attention deficit/hyperactivity disorder

CANS central auditory nervous system CAP central auditory processing

CAPD central auditory processing disorder

sensitive period the ideal period for neuroplasticity to occur

AT auditory training

CNS central nervous system

**Figure 3.** *CAPD and associated pathologies.*

*Neuroplasticity and the Auditory System DOI: http://dx.doi.org/10.5772/intechopen.90085*

with a documented history of bilateral ventilation tube insertion, highlighted some aspects of auditory neuroplasticity. According to the data from the study, the participants were randomly divided into two groups: (i) auditory training and (ii) visual training. In the behavioral tests during the pre-intervention evaluation, no statistical differences were detected. However, after the auditory training program, there was an improvement in the subjects' performance for auditory abilities. In addition, comparing the two types of intervention (visual vs. auditory), the behavioral tests revealed better responses to the post-intervention auditory training. The results, assessed through behavioral tests on subjects with a history of bilateral otitis media, suggest that auditory training provided beneficial gains for all auditory abilities.
