**3. Testing the central auditory processing of children with a history of otitis media**

To evaluate central auditory processing in children with a history of OM, it is recommended that a battery of test procedures be used by which the mechanisms and auditory abilities involved in the analysis and interpretation of sounds can be investigated. Due to the complexity of CANS, no single test is sufficient to explore its nature [3, 4]. Since the 1950s, numerous tests have been developed to evaluate central hearing function. These tests differ in that each presents different types of stimuli (verbal or nonverbal) and involves presentation to one or both ears (monaural or binaural). Each test is designed to evaluate a particular auditory mechanism or auditory ability and consequently probes different areas and functions of the CANS. Below the tests are divided into categories according to the way in which the stimuli are presented to the ears, the nature of the auditory tasks involved, and the method or approach used. Other currently accepted classifications involve categorizing them as binaural interaction tests, dichotic tests with verbal and non-verbal sounds (binaural integration and separation), monaural tests using low redundancy stimuli, time processing tests, and electroacoustic and electrophysiological procedures [20].

A comprehensive assessment allows for correct quantification and qualification of the various CANS mechanisms and dysfunctions and provides important information for planning and managing treatment.

### **3.1 Behavioral evaluation**

Research by Colella-Santos et al. [11] involved 50 children (28 boys, 22 girls, mean age 11.2 years) with a documented history of bilateral SOM in the first 6 years of life and who had bilateral tympanostomy tube insertion (experimental group, EG); a control group (CG) consisted of 40 children (17 boys, 23 girls, mean age 10.7 years) with no history of otitis media. All children had auditory thresholds within normal limits on the day of evaluation and had a type A tympanometric curve. They were all evaluated with the tests described below [21–23]. The tests were the dichotic digits test, synthetic sentence identification test, gaps-in-noise test, and frequency pattern test. Details are as follows **Figure 2a** and **b**.

#### *3.1.1 Dichotic digits (DD)*

The DD test as developed in Brazil consists of four presentations of a list of twosyllable digits in Brazilian Portuguese, in which four different digits are presented simultaneously, two in each ear. The list contains 40 randomly arranged pairs of digits presented at 50 dB HL. The digits used to form the numbers are four, five, seven, eight, and nine. The participants are instructed to listen to two numbers in each ear and repeat all the numbers they hear. The order does not matter. The dichotic digits test verifies binaural integration ability [21].

**69**

*Otitis Media, Behavioral and Electrophysiological Tests, and Auditory Rehabilitation*

The SSI test consists of the presentation of 10 Brazilian Portuguese sentences at 40 dB HL, in the presence of a competing children's story in the same ear at a signal-to-noise ratio of 0, −10, or −15 dB. The task of the subject is to listen to the sentence and point to it in a frame. The ability analyzed in this test is figure-ground

The FPT test is composed of three 150 ms tones presented at 50 dB HL and separated by 200 ms. The tones in each triplet are combinations of two sinusoids, 880 and 1122 Hz, which are designated as low frequency (L) and high frequency (H), respectively. Thus, there are six possible combinations of the three-tone sequence (LLH, LHL, LHH, HLH, HLL, and HHL). The subjects are instructed that they will hear sets of three consecutive tones that vary in pitch. Their task is to repeat the pattern by humming and verbalizing the frequency pattern (e.g., high–low–high).

The GIN test consists of a series of 6-second segments of broad-band noise presented at 50 dB HL with 0–3 gaps embedded within each segment. The gaps vary in duration from 2 to 20 ms. The gap-detection threshold is defined as the shortest duration that is correctly identified at least four out of six times. The participants are instructed to indicate each time they perceive a gap. The GIN test measures

To establish a difference between the right and left ears of subjects in the EG, it was necessary that there was a statistically significant difference in both the Dichotic Digits (*p* = 0.001) and GIN (*p* = 0.004) tests. No significant difference was found for gender in the behavioral tests. It was observed that the EG had lower mean responses than the CG for the DD test of approximately 5% in both ears; for the FPT 9.6% (humming) and 30% (naming); and 8% for the SSI test. For the GIN test, there was a statistically significant difference in the gap-detection threshold between the groups, with the highest threshold obtained in the EG compared to the

In summary, there was a negative effect of OM on the auditory skills of figurebackground discrimination, resolution, and temporal ordering. The poorer results in CAP behavioral tests in the EG participants can be explained by the fact that OM,

*DOI: http://dx.doi.org/10.5772/intechopen.88800*

*3.1.2 Synthetic sentence identification (SSI)*

*(a–b) Tympanostomy tube insertion. Personal collection.*

discrimination [21].

**Figure 2.**

*3.1.3 Frequency pattern test (FPT)*

*3.1.4 Gaps-in-noise (GIN)*

temporal resolution ability [23].

The FPT test checks temporal ordering ability [22].

CG (the higher the threshold, the worse the performance).

*Otitis Media, Behavioral and Electrophysiological Tests, and Auditory Rehabilitation DOI: http://dx.doi.org/10.5772/intechopen.88800*

**Figure 2.** *(a–b) Tympanostomy tube insertion. Personal collection.*

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

age of three can have had 12 months of conductive hearing loss, which is a third of the period considered critical for development and learning [19]. The periods of auditory deprivation during the active periods of OME over the first years of life can delay the maturation of the structures in the CANS and consequently impair

Therefore, evaluation of auditory processing is fundamental in children with a history of otitis media in order to allow diagnosis, intervention, and guidance.

**3. Testing the central auditory processing of children with a history of** 

To evaluate central auditory processing in children with a history of OM, it is recommended that a battery of test procedures be used by which the mechanisms and auditory abilities involved in the analysis and interpretation of sounds can be investigated. Due to the complexity of CANS, no single test is sufficient to explore its nature [3, 4]. Since the 1950s, numerous tests have been developed to evaluate central hearing function. These tests differ in that each presents different types of stimuli (verbal or nonverbal) and involves presentation to one or both ears (monaural or binaural). Each test is designed to evaluate a particular auditory mechanism or auditory ability and consequently probes different areas and functions of the CANS. Below the tests are divided into categories according to the way in which the stimuli are presented to the ears, the nature of the auditory tasks involved, and the method or approach used. Other currently accepted classifications involve categorizing them as binaural interaction tests, dichotic tests with verbal and non-verbal sounds (binaural integration and separation), monaural tests using low redundancy stimuli, time processing tests, and electroacoustic and electrophysi-

A comprehensive assessment allows for correct quantification and qualification of the various CANS mechanisms and dysfunctions and provides important

Research by Colella-Santos et al. [11] involved 50 children (28 boys, 22 girls, mean age 11.2 years) with a documented history of bilateral SOM in the first 6 years of life and who had bilateral tympanostomy tube insertion (experimental group, EG); a control group (CG) consisted of 40 children (17 boys, 23 girls, mean age 10.7 years) with no history of otitis media. All children had auditory thresholds within normal limits on the day of evaluation and had a type A tympanometric curve. They were all evaluated with the tests described below [21–23]. The tests were the dichotic digits test, synthetic sentence identification test, gaps-in-noise

The DD test as developed in Brazil consists of four presentations of a list of twosyllable digits in Brazilian Portuguese, in which four different digits are presented simultaneously, two in each ear. The list contains 40 randomly arranged pairs of digits presented at 50 dB HL. The digits used to form the numbers are four, five, seven, eight, and nine. The participants are instructed to listen to two numbers in each ear and repeat all the numbers they hear. The order does not matter. The

test, and frequency pattern test. Details are as follows **Figure 2a** and **b**.

dichotic digits test verifies binaural integration ability [21].

auditory abilities associated with central auditory processing.

**otitis media**

ological procedures [20].

**3.1 Behavioral evaluation**

*3.1.1 Dichotic digits (DD)*

information for planning and managing treatment.

**68**

### *3.1.2 Synthetic sentence identification (SSI)*

The SSI test consists of the presentation of 10 Brazilian Portuguese sentences at 40 dB HL, in the presence of a competing children's story in the same ear at a signal-to-noise ratio of 0, −10, or −15 dB. The task of the subject is to listen to the sentence and point to it in a frame. The ability analyzed in this test is figure-ground discrimination [21].

#### *3.1.3 Frequency pattern test (FPT)*

The FPT test is composed of three 150 ms tones presented at 50 dB HL and separated by 200 ms. The tones in each triplet are combinations of two sinusoids, 880 and 1122 Hz, which are designated as low frequency (L) and high frequency (H), respectively. Thus, there are six possible combinations of the three-tone sequence (LLH, LHL, LHH, HLH, HLL, and HHL). The subjects are instructed that they will hear sets of three consecutive tones that vary in pitch. Their task is to repeat the pattern by humming and verbalizing the frequency pattern (e.g., high–low–high). The FPT test checks temporal ordering ability [22].

### *3.1.4 Gaps-in-noise (GIN)*

The GIN test consists of a series of 6-second segments of broad-band noise presented at 50 dB HL with 0–3 gaps embedded within each segment. The gaps vary in duration from 2 to 20 ms. The gap-detection threshold is defined as the shortest duration that is correctly identified at least four out of six times. The participants are instructed to indicate each time they perceive a gap. The GIN test measures temporal resolution ability [23].

To establish a difference between the right and left ears of subjects in the EG, it was necessary that there was a statistically significant difference in both the Dichotic Digits (*p* = 0.001) and GIN (*p* = 0.004) tests. No significant difference was found for gender in the behavioral tests. It was observed that the EG had lower mean responses than the CG for the DD test of approximately 5% in both ears; for the FPT 9.6% (humming) and 30% (naming); and 8% for the SSI test. For the GIN test, there was a statistically significant difference in the gap-detection threshold between the groups, with the highest threshold obtained in the EG compared to the CG (the higher the threshold, the worse the performance).

In summary, there was a negative effect of OM on the auditory skills of figurebackground discrimination, resolution, and temporal ordering. The poorer results in CAP behavioral tests in the EG participants can be explained by the fact that OM, by generating a fluctuating auditory threshold and causing temporary auditory deprivation, hampers the maturation of auditory abilities (such as binaural integration, resolution, temporal ordering, and discrimination) which are fundamental for understanding speech. During this period of auditory deprivation due to episodic OM, the CANS received inconsistent and incomplete auditory information. That is, the period between clinical assessment and the decision to perform surgery may have been too long **Table 1**.

Recent research has demonstrated associations similar to those found in the present study. Borges et al. [11] studied the effect of OM in 69 children of different socioeconomic levels who underwent surgical intervention (insertion of ventilation tubes) and observed worse performance in both the DD and GIN tests. The authors concluded that a history of OM can lead to changes in central auditory functioning, regardless of socioeconomic status.

Khavarghazalani et al. [24] evaluated 12 children with a history of OM who had undergone surgical intervention for insertion of ventilation tubes and found worse performance in the DD and GIN responses than in normals.

Gravel and Wallace [25] also found a significant increase in signal-to-noise ratio in a prospective study of children with a history of OM. There was worse performance on the SSI test (responsible for the figure-ground ability) in the OM group.

Tomlin and Rance [26] recommend that children with a history of OM undergo an evaluation of spatial processing upon entering school. They studied 35 children with a history of chronic OM and found a statistically worse performance compared to the control group in the listening in spatialized noise-sentences test (LISN-S). They concluded that these children have altered spatial processing, difficulty in focusing attention on the relevant stimulus, and difficulty in simultaneously suppressing competing stimuli coming from other directions. It is hypothesized that fluctuating access to binaural cues, caused by OM, may negatively affect the development of spatial processing in the CANS.
