The use of remote microphone systems in unilateral hearing loss: a preliminary study among Brazilian children and teenagers

Abstract Due to the large number of individuals with Unilateral Hearing Loss (UHL) and the recommendation to use hearing assistive devices, studies are required to define possibilities of intervention for this population. Objective: To evaluate the performance of the Remote Microphone System (RMS) in children with UHL. Methodology: Prospective clinical study with a convenience sample. Eleven children (mean age of 9.2 years) with severe and profound sensorineural UHL, hearing aid users and enrolled in regular schools participated in the study. They were evaluated using the Hearing in Noise Test (HINT), the Classroom Participation Questionnaire (CPQ), and the Sustained Auditory Attention Ability Test (SAAAT) with RMS. Results: HINT results were analyzed using variance to three criteria of repeated measures, which revealed differences between intervention, position, and time factors and significant interaction between these three factors. The comparative analysis of the results from CPQ showed significant differences in the statistical t-test (p=<0.001) for all subscales. The analysis of variance at two repeated measures criteria used in the study of SAAAT revealed a difference between intervention and time, and both interacted significantly. Conclusion: The RMS associated with a hearing aid was effective for individuals with UHL.


Introduction
The difficulties faced by children with unilateral hearing loss (UHL) are an essential demand in hearing health services. No consensus is reached on the treatment to this problem.
Nontreatment of UHL is considered a standard of care assistance in many parts of the world. Historically, doctors and researchers believed children with this type of hearing loss could have normal development since they had only one compromised ear. However, in the late 1980s, researchers began to detect significant academic problems in this population. Since then, studies have suggested children with UHL have a significant risk of speech, language, academic, and behavioral delays. 1,2,3 With identification and early intervention, parents learn about the impact of hearing loss on child development. In Brazil, this became possible after the approval of Law 12.303 of August 2, 2010, which makes the Universal Newborn Hearing Screening Program mandatory. 4 As a consequence, the age of detection of UHL in Brazil fell dramatically from school age to early childhood. 5 In a recent study conducted in Ontario, Canada, with 20 children diagnosed with UHL, the mean age of identification was 4.6 months. Parents experienced significant uncertainty about the need to use amplification devices because the hearing loss and its potential impact on the child's development were considered minimal. 6 In fact, among the communication difficulties caused by hearing loss, the ability to understand speech in noisy environments is a daily challenge, 2 considering that most communicative situations occur in places where listening is hampered by the presence of competitive noise.
In classroom, understanding is critical for the child to master academic skills, such as determining the main idea, following directions, answering questions, and participating in class discussions. A sensory impairment can affect the concentration, grammatical and lexical knowledge, working memory, cognition, past experiences, and mental and physical state. 7 Kuppler, et al. 8 (2013) carried out a systematic review with articles from 1986 to 2012 regarding the academic performance of children with UHL.
They observed hearing deprivation encompasses not only difficulty understanding speech in noisy places, but also exhaustion, self-esteem problems and, consequently, the need for greater effort to sustain auditory attention.
In another study, sustained auditory attention was evaluated in 90 children aged from 7 to 11 years.
The children were separated in three groups, with 30 children each: normal hearing; diagnosed with mild bilateral conductive hearing loss; and diagnosed with mild bilateral sensorineural hearing loss. The authors concluded that sensorineural hearing loss causes greater impairment of sustained auditory attention when compared with conductive hearing loss. 9 This ability can also be evaluated according to the period of the day and the type of school attended by the child. Picolini, et al. 10   The more negative the ratio, the greater the difficulty, because the signal is emitted below the noise intensity.

Classroom Participation Questionnaire (CPQ)
The CPQ is a subjective assessment tool that provides a situational analysis of student participation in classroom. It is a student-rated measure that contains 28 auditory situations divided into four subscales: (1) Understanding Teachers; (2) Understanding Students; (3) Positive Affect; (4). Negative Affect.
In each scale, the student scores choosing between

Sustained Auditory Attention Ability Test (SAAAT)
The SAAAT is based on the Auditory Continuous Performance Test (ACPT), which is clinically used to measure auditory attention, and was performed in the free field. 18 It is a method of evaluating the child's ability to listen to auditory stimuli over an extended period and to respond only to a specific stimulus. It consists of binaural and dichotic presentation of 21 monosyllabic words randomly rearranged and repeated to form a list of 100 words, with 20 occurrences of the target word "no". This list, recorded on CD, was presented six times uninterruptedly, thus totaling 600 words, lasting approximately 10 min.
To determine the performance in this test, the children were instructed to raise their hand upon hearing the target word "no". Two types of errors were considered: inattention error, when the child did not raise the hand in response to the target word, and impulsiveness error, when the child raised the hand in response to another word other than "no". The score was calculated adding the number of inattention errors to the number of impulsiveness errors.
Vigilance was estimated by adding the number of correct answers for the word "no" during the sequence of the six presentations. The estimate was necessary to verify the decline in vigilance, i.e., the decline in the attention that occurred during the vigilance task, obtained by estimating the number of correct answers for the word "no" in the 1 st presentation and the number of correct answers for the 6 th presentation.
The difference between these two numbers is called "decreased vigilance." To verify the better form of fitting of the RMS, To avoid learning effect on the evaluations, the different conditions were applied with a 15-day interval, according to Keith 19 (1994), and the Latin Square Design was used to present the children's evaluation conditions.  The use of remote microphone systems in unilateral hearing loss: a preliminary study among Brazilian children and teenagers analysis of the "teacher comprehension" and "peer comprehension" showed normal distribution of the data and homogeneity of the variances, so the Student's t-test was used. For the "positive and negative aspects," data were not normally distributed, so the nonparametric Mann-Whitney test was used.

Statistical analysis
For the SAAAT data, parameters of normality and homogeneity were verified; therefore, they were submitted to the test of analysis of variance for two criteria of repeated measurements.
For all cases, a significance level of 5% was adopted.

Results
Since HINT is a sentence repetition test, age is not expected to influence the results. The results were studied through analysis of variance for two criteria of repeated measures, in which differences between intervention and time factors were observed. However, the same test revealed a significant interaction between these two factors, and the Tukey's post hoc analysis allowed the verification of these differences, shown in Table 1.

Improvement in the responses in all HINT situations
using the RMS was observed.
The comparative analysis of the results from the Classroom Participation Questionnaire, with and without the use of the RMS, showed significant differences in the statistical t-test (p=<0.001) for the subscales "teacher comprehension" and "peer comprehension", since (Shapiro-Wilk test) homogeneity of variances (Levene's test) were observed in these cases. In the "positive aspects" and "negative aspects," data were not normally distributed (Shapiro-Wilk test). The use of the nonparametric Mann-Whitney test indicated a statistically significant difference between groups (Tables 2, and Figures 2 and 3).       (Table 1). After statistical analysis, no significant difference between the RMS positioning conditions was observed. These results are similar to those found by Updike 21 (1994) and Tharpe, et al. 22 (2004), which report improvement in speech recognition in children with UHL in a situation of noise and silence using the RMS.
Regardless of the HINT application, the software itself uses the composite noise (CN), which is a weighted average of the NF/NR/NL conditions for the free field application. The results from the CN (Table   1)  The study [23][24][25] reported that the best expected responses are in the noise and speech condition separated by 90º, with speech at 0º in front of the individual and the noise at 90º to the right or left. In this study, the best values were obtained with the RMS only in the ear without hearing loss, with a mean of -5.6 for NR and -4.5 for NL.
The NR and NL results (Table 1) were better with the system attached to the ear without involvement, with speech at the front and noise at the side of the ear with hearing loss, justifying the data similar to those surveyed in subjects with normal hearing. 23,24 Regarding NF, the children studied presented lower rate of improvement by using the RMS, presenting a response value of -2.6 with the use of HA and the RMS positioned in the affected ear. This is the best result concerning the speech perception in noise front (Table 1). These results agree with those of previous studies 23,24,26 that evaluated children and adults.
The value of -6.04 from the NB with HA and RMS in the affected ear (Table 1)  The HINT was used to evaluate children and teenagers with cochlear implants, with different box placements and stimuli. The results were significant when comparing the responses with and without the RMS. 29 The benefit of the RMS is devoted to bilateral hearing loss and has also proved to be effective for UHL.   on the stimulus when the teacher's speech becomes clearer, while ignoring the competitive stimulus.
According to the literature, younger children have a limited attention span and, as they develop it, the internal processing mechanism changes, increasing this capacity. Therefore, older children, aged 11 years, perform better than younger children in this ability. 37,38 Although the mean age of the children evaluated in this study was 9.2 years, the results after three months of use of the RMS were compatible with the responses of children with normal hearing in the 11-year age group. 39 The participants used the HA/RMS in classroom according to the proposal of the study, with results with poor statistical significance. In the HINT and SAAAT evaluations, the children reported that classroom situations became easier to understand and, at the end of the period, they were less tired (less auditory effort).
Informally, the children reported higher concentration to receive the teachers' explanation and to better understand the subjects. The children also reported that asking the teacher to repeat what was just said during dictation activity was no longer necessary.
In a systematic review of sound amplification devices for unilateral sensorineural hearing loss of severe and profound degrees in adults, the authors suggest researchers conduct further studies on effectiveness of sound amplification devices for this type of hearing loss, thus supporting efforts for new evidences. 40 Finally, it should be recognized that UHL is a crucial problem for school-aged children and that increasing studies for interventions that benefit this population is necessary.
The results of this investigation evidence that the RMS should be indicated for children with UHL, mainly for use in classroom, regardless of the fitting condition.
This investigation was carried out with 11 children, because it is a study that requires periodic returns to the clinic, control of the use of devices and availability of equipment. Thus, the sample number is small, similar to international surveys conducted with children with UHL. 3,6,30,33 We highlight that no previous studies on UHL have similar methodology and literature on this subject is limited. 8

Conclusion
The research participants presented superior results using the RMS in evaluations of speech perception, sustained auditory attention, and classroom participation, regardless of the fitting condition, suggesting the effectiveness of this device associated with a hearing aid for children with unilateral hearing loss.