Auditory Processing Disorder (APD) – Be vigilant and aware

Auditory Processing Disorder (APD) are defects of the auditory sense, which result from abnormalities in the functioning of the auditory path at the level of the central nervous system from the center of the Cochlea to the auditory cortex. This is a problem that 2-3% of children, aged 7-14 suffer from in Poland. The aim of this paper is to establish a spectrum of the most common symptoms as well as to determine the most common age range of the children that have been diagnosed. A retrospective analysis was conducted, based on the medical documentation of patients diagnosed and treated in the audiological clinic. The examined group consisted of 215 children ages 6 to 18. The inclusion criteria were as follows: normal peripheral hearing and an IQ indicator of at least 85. Data was analyzed with the use of STATISTICA 9.1 program. The highest number of children were admitted with problems connected to writing (78,15%), reading (69,77%), and concentrating (60,93%). The most common symptomsamong patients who have been diagnosed with APD)were as follows: late speech development (96%), speech defects (91,4%), problems with learning a language (91,67%). The most numerous group represented were patients aged 10 to 12 (40,93%). The accuracy of the initial diagnosis was the highest in the 6 to 7 age group (96,15%). The results of this paper speak for the necessity of increasing APD awareness among people close to a child as the problems that emerge are common and a lot of the diagnoses late. Correspondence to: Beata Kazek, Neurological Clinic, John Paul II Upper Silesian Child Health Centre, Poniatowskiego 15, Katowice, Poland, E-mail: neurologia@gczd.katowice.pl / beakazek@op.pl


Introduction and aim
Auditory Processing Disorder (in short -APD) consists of problems in the interpretation of auditory information at the level of the central nervous system with a correct reception of said information by the peripheral structures. It is estimated, that this problem concerns 2-3%, and according to some authors even 5% of Polish children ages 7-12 [1,2].
According to the data of the American Speech-Language-Hearing Association (ASHA) people with APD suffer from difficulties in understanding speech amongst noise, localizing and directing sound, differentiating sounds that are similar to each other as well as temporal sound processing. The first symptoms among children may manifest by speech development abnormalities and difficulties in articulating sounds.
In a school environment, children suffering from APD, despite having normal intelligence levels, have a lot of problems due to improper processing of sound impulses. This manifests itself in difficulties in learning how to read, write and problems with concentration that result from the inability to correctly understand the teacher's directions, to follow his statements and poor auditory memory. These children struggle with low self-esteem, have bigger problems with managing stress as well as emotional and social problems [3,4]. That is why proper diagnostics of those disorders is so important.The introduction of tests for these disorders was preceded by coplete electrophysiological test as well as imaging tests of the auditory pathway.It was concluded, that the described symptoms are a result of central damage in the case of patients whose peripheral hearing was normal. Furthermore, imaging showed damages in the area of the cortex responsible for understanding speech. Even though one abnormal result from among the tests describedin the methodology is enough to recognize APD, both its sensitivity and specificity is low. It increases considerably in the case of 3 abnormal tests. Given this assumption, the sensitivity of the test used by the authors is around 70%, whereas the specificity is at the level of 80%.
The aim of this paper is to establish a spectrum of the most common symptoms as well as to determine the most common age range of the children that have been diagnosed with auditory processing disorder. Based on the information which age group was predominant among patients with suspected APD and the information what the accuracy of the suspicions was the aim is to determine whether the awareness of this problem among primary school children is sufficient.
Auditory Processing Disorder (in short -APD) consists of problems in the interpretation of auditory information at the level of the central nervous system with a correct reception of said information by the peripheral structures. It is estimated, that this problem concerns 2-3%, and according to some authors even 5% of Polish children ages 7-12 [1,2].
According to the data of the American Speech-Language-Hearing Association [ASHA] people with APD suffer from difficulties in understanding speech amongst noise, localizing and directing sound, differentiating sounds that are similar to each other as well as temporal sound processing. The first symptoms among children may manifest by speech development abnormalities and difficulties in articulating sounds.
In a school environment, children suffering from APD, despite having normal intelligence levels, have a lot of problems due to improper processing of sound impulses. This manifests itself in difficulties in learning how to read, write and problems with concentration that result from the inability to correctly understand the teacher's directions, to follow his statements and poor auditory memory. These children struggle with low self-esteem, have bigger problems with managing stress as well as emotional and social problems [3,4].
The aim of this paper is to establish a spectrum of the most common symptoms as well as to determine the most common age range of the children that have been diagnosed with auditory processing disorder.

Materials and methods
The data of 215 children were analyzed, including 61 girls and 154 boys aged 6 to 18. These patients were diagnosed in view of APD in the Audiological Clinic at the John Paul II Upper Silesian Child Health Centre in Katowice. The conditions of inclusion into the study included positive peripheral hearing tests (impedance and tonal and also acoustic otoemission -OTE) and the results of an IQ test (WISC-R) of above 85. Exclusion criteria were as follows: correct results of the peripheral hearing test, WISC-R below 85 and incomplete patient data. Four age groups were distinguished according to the levels of school education (which result from a child's age). The first group was children aged 6 and 7 attending preschool of first grade of primary school. The second group consisted of 8 and 9 year olds that attend the second and third grade, i.e. elementary education. The third group consisted of children from 10 to 12 years old which are grades 4 to 6, and finally the last group were children aged 13 and above, attending middle and high schools.
The confirmation of the initial diagnosis was established if the results of at least three of the following tests were not correct:

1.
Duration Pattern Test (DPT) or Speech Perception Test (SPT), during which the patient hears three sounds with different length or frequency and the aim is for him to recognize and arrange the tones in order;

2.
Compressed Speech Test (CST), during which the patient recognizes monosyllabic words subjected to temporal compression;

3.
Filtered Speech Test which consists of repeating 20 words heard in sequence, which were first distorted by a filter;

4.
Sound in Noise Test (SIN) which requires the patient to repeat words heard amongst noise at the frequency of 3dB.

5.
Gap Detection Test (GDT), during which noises and gaps are presented alternatively and the patient has to recognize them using a button;

6.
Dichotic Digit Test (DDT) which consists of repeating two different pairs of numbers that are simultaneously given into each ear;

7.
Integration test, which is a part of DDT, during which the patient repeats numbers he hears, that are directed to both ears. This test measures the transfer of information between the hemispheres. The integration process translates into the ability to combine different information presented simultaneously into both ears;

8.
Competing Words Test, during which the patient hears different words in each ear simultaneously and has to repeat the word from the left and right ear. This is a test that evaluates the ability to split attention.
All tests were executed in identical conditions. The child was sat down in a specially muted room that was isolated from any external noise and was given headphones through which the technician's instructions and successive stages of the tests were given. Several tests were carried out during one day with rest periods of a few days in order to prevent the child from losing interest and reluctance to participate.
A database was established, which contained information such as: gender; age during the time of the tests; problems reported during the consultation with an audiologist, which may be connected to APD -mainly problems with reading, writing, focusing and speech impediments.The demographic and clinical data was processed using the STATISTICA 9.1 program. The test that was used was connected to qualitative variables -CHI2 with the Yates correction. During the log-linear analysis a statistically relevant effect of two-dimensional interaction was identified.

Results
From the 215 patients that were directed to the audiological clinic with suspected disorders of central auditory processing, 78,14% had their initial diagnosis confirmed. Table 1 contains the age scope of the examined children. The accuracy of APD suspicions among respective age groups is presented in table 2. The largest group among the directed children was 10-12 years old (40,93%). The smallest group consisted of children aged 6 to 7 (12,09%). It is worth mentioning that the accuracy of the diagnosis was largest in this group and was 96,15%. Another noteworthy fact is that the group of patients that were directed late (meaning above the ages of 12), meaning children that are in middle school, was significant. This group consisted of 16% of all patients.
Based on the CHI2 with the Yates correction in unifactorial analysis for the accuracy of the diagnosis a significant difference in the distributions was stated Also noteworthy, is the fact that boys were directed to examination of central auditory processing more often than girls, adding to the fact that the boys to girls ratio within the younger age groups was 2:1. That discrepancy gets even larger with age as the ratio reaches the level of 3:1 in the 10-12 years old age group (Table 3). Among patients with confirmed APD, this ratio is similar, reaching almost 3:1 at the peak -10-12 year olds ( The results of tests for partial and marginal associations in the multifactorial log-linear analysis for two-dimensional interactions are presented in table 5.A relevant interaction between the age group and the APD diagnosis was established (Table 5).
Problems reported by parents of children directed to an audiologist according to a descending frequency of reporting are gathered in table 6. The largest number of parents as well as children reported problems with writing. Other often reported issues consisted of difficulties concentrating, speech impediments and not having obtained age appropriate reading skills.
The most common issue among patients diagnosed with APD is a delayed development of speech during childhood, problems at school (mainly in learning languages and math), speech impediments and delayed (Table 7).

Discussion
APD concerns a large population of children, since 3 out of a hundred children in Poland, ages 7 to 13, suffer from this disorder. In his paper published in 2015 De Bonis paid special attention to the importance of diagnosing the disorders of functions such as memory, concentration and problems with the utilization of language in the overall recognition of the issue [5]. Other problems most commonly listed in literature involve problems with hearing in noise and in spaces that have echoes, difficulties with following verbal instructions, misinterpreting short words, frequent asking to repeat statements and distracted focus [6]. Other areas that are being focused on are the capacity of the working memory and auditory lateralization [7]. This corresponds with the results of a study conducted by the authors, which show that the main problems for children with diagnosed APD are: a delayed development of speech (96%), problems with the Polish language (91,67%), speech impediments (91,04%). Also common (seen with around¾ of the examined patients), were slow work tempo, problems with math, remembering, expressing oneself, foreign languages, reading, understanding verbal instructions, writing and concentration.
These kind of symptoms certainly have a negative effect on a child that functions in a school environment. This leads to school results worse than they would be based on the global intellectual evaluation of the child. It also leads to low self-esteem and emotional disorders of various intensities.

Interaction Partial Association Peripheral association
Medical specialty -Age group NS (p=0,99) NS (p=0,98) Medical specialty -Confirmation of the diagnosis NS (p=0,11) NS (p=0,09) Age group -Confirmation of the diagnosis p=0,009 p=0,005  used evaluations of central auditory processing for children are to be carried out from age 7 onwards (2015 year).The reasons for that are complex, with the main focus being on the development process of the auditory pathways, but also problems with getting younger patients to cooperate on a satisfactory level. There is a lack of set norms for children under the age of 7. Age is a compromise of sorts, that takes into account the fact that on the one side the maturity of the auditory pathway enables it to function close to the level of adults around the age of 12, and on the other side at the age of 7 the overall maturity is advanced enough in order to establish a good level of cooperation with the child [8].It is also the beginning of education at school. The fact that children from that age group are rarely directed (up to date) to an audiologist may be linked to the fact that clear defects of auditory perception such as problems with reading, writing, expressing oneself and concentration in a class conditions are much more visible in a school environment. That is the time that these defects are being recognized by parents and educators.
The results of our analysis indicate, that the accuracy of the diagnosis was most accurate (96,15%) in the 6 to 7 age group. The majority of this group however, was children that were 7; the analysis includes only three children that were about to (within the following months) turn 7 that had a high intellectual potential. They The youngest 7 year old and children about to turn 7 were directed to the audiological clinic for APD diagnostics the least (12,09% of all directed patients).
In research conducted in Poland, children were subjected to the Dichotic Digit Test (DDT) [9]. A non-correct result was recorded in 11,4% of cases at children aged 7 and in 11,3% of children aged 12. The authors of this research suggest, that screening tests of the central auditory processing should be conducted among school children. Proceeding in this direction will help find those who suffer from above described problems amongst small children and, in consequence, enable taking steps towards correcting them at an early stage. Following that logic even further, the optimal situation would be if those tests were conducted at a pre-school age.
There is an increase of interest in disorders of the central auditory processing, including the issue of the possible methods of early detection of said disorders [10]. Attempts are taken to examine children under the age of seven with objective methods. This kind of objective examination could be very helpful and important in the case of diagnosing children for which tests for APD are not age appropriate. A research that uncovered the differences in the transiently-evoked otoacoustic emissions(TEOAEs) in children suffering from APD compared to ones that are healthy. The research showed that counterlateral otoemission suppression is more common with children with APD compared to the control group [11]. Perhaps further research and a standardization of objective tests will enable diagnosing children in the pre-school age.
Finding those disorders is all the more important, as patients suffering from APD can be helped. First of all, the school acoustic environmentcan be improved. According to ASHA standarts, the background noise of tehenvirinment in which child is studying should not exceed 30 dB, reverberation can last up to 30 sec and the signal to noise ratio should be lower than 15 dB. This can be achieved by, for example, using noise reducing curtains, howevere it is a difficult issue and at the moment rarely attained [12]. There are also the so called Frequency Modulation (FM) systeme that support hearing in noisy places [13]. Auditory training is also important. Mc Arthur in his research (2009) concluded that instructing and simple speech training can have a positive impact in terms of auditory processing in children [14]. It seems that specially programmed video games, which allow for active training, have considerable potential. They allow for gradation of the difficulty level, to adjust and ti increase it based on the child's capabillities [15] The methods which are currently quite frequently used, that involve passive listening to specially crafted musical programs are somewhat controversial. These methods are not recommended until convincing scientific research is published. Novadays, school implement special methods for education of children with this problem i.e., individual teaching on school grounds in terms of specific subjects and / or teaching in smaller groups. Various aiding devices are also being used, which enables children suffering from APD to work more efficiently.
If it cannot be done at an earlier age, children that should be focused on are those, which have significant problems in the first grade of primary school despite having adequate intellectual potential and support from their parents.

Conclusions
The findings of the research conclude, that the knowledge among educators, parents and primary care physicians concerning disorders of the central auditory processing is insufficient, which is why school children are often directed for APD testing late. Symptoms such as delayed speech development; speech impediments; significant  problems with acquiring new skills in first grade despite adequate intellectual potential and support from the parents; difficulties in learning languages, math and concentrating should be considered as red flags as they may indicate the child suffers from APD. It is necessary to raise awareness and vigilance in terms of these issues among people close to the child physicians, especially pediatricians and pediatric neurologists. The benefits of early diagnosis and, in consequence taking appropriate actions cannot be overstated.