Auditory and Vestibular Research
Volume:20 Issue: 1, 2011

High incidence of speech disorders in children with cerebral palsy could be related to a deficiency in processing of auditory stimuli. So it is vital to check out any peripheral or central disorders in auditory system using behavioral and electrophysiological auditory tests.

In a cross-sectional study, 15 children with spastic diplegia, mean age 5.77, SD 2.26 years, and 15 normal children, mean age 5.33, SD 1.80 years, were tested using pure tone audiometry, immittance and auditory brainstem responses. The results were compared between the two groups.

Hearing thresholds and middle ear status were in normal range in all participants; however, contralateral acoustic reflex thresholds were mostly elevated. Comparing absolute latency and interpeak latency intervals of auditory brainstem responses between the two groups, absolute latency interval of later waves, and in specific the V wave, was significantly longer in diplegic children (p=0.04) resulting in a longer III-V interpeak latency intervals (p=0.02).

Neurological disorders in ponto-reticulo-spinal pathway, pontine reticular nuclei and upper pons which are adjacent to auditory nuclei of lateral leminiscus and inferior colliculus result in auditory dys-synchrony and increased latency intervals in latter waves of auditory brainstem responses. This could also attributed to functional disorders in wave-generating sites in these patients.

Hearing impairment through the primary episode of development has an undeniable effect on communicative language and cognitive ability of children. The purpose of this study was to compare primary verbal, nonverbal and mathematical concept formation, between children with and without hearing impairment. In this study 88 children with normal and impaired hearing were compared in four-, five- and six-year old age groups. Normal children were selected randomly and the other group consisted of the available children with impaired hearing. To evaluate verbal, nonverbal and mathematic concepts, a test was designed and developed based on language and cognitive developmental scale in normal children. Significant difference was seen in the average scores in each concept class between normal and impaired hearing group in all age groups (p<0.05). There was no statistical significance between girls and boys. Hearing groups had statistical significant difference in each group of concepts (p<0.001). Age had statistical significance only in mathematics’ concepts (p=0.001). This study supports the necessity of assessing the understanding of verbal, nonverbal and mathematic concepts, as well as cognitive and verbal skills in children with hearing impairment, prior to any formal education program planning. The curriculum should be arranged according to these abilities and skills. Otherwise it would be hardly practical and functional for these children to go through the curriculum which is planned without any notion to their basic abilities.

Patients with migraine commonly show vestibular symptoms. However, abnormal neurotological test findings during the inter-attack intervals, even in the absence of vestibular symptoms, are suggestive of subclinical vestibular dysfunction in migraine. This study aimed to compare the vestibular evoked myogenic potentials between migraine patients and normal individuals. Subjects included 25 patients with migraine and 26 healthy volunteers with an age range of 20-53 years old. The vestibular evoked myogenic potentials were recorded with 500 Hz tone bursts at 95 dB nHL. Mean of absolute amplitude and p13 latency values in the migraine group were significantly less and more than the normal group, respectively (p=0.001 for absolute amplitude in right and left ears; p=0.004 for p13 latency in right ears and p=0.02 in left ears). There was no statistically significant difference between the two groups in mean of the n23 latency and also the amplitude ratio (p>0.05). According to the prolonged latency of vestibular evoked myogenic potentials response, vestibulospinal tract in brainstem is probably involved in migraine patients. However, due to small sample size, for generalizing this result to all patients with migraine, further researches are needed.

Hearing-impaired children make a lot of stress for the parents. Providing the parents of these children with suitable consultation and rehabilitation services results in increased satisfaction and reduced anxiety level. In this study we investigated the relationship between audiology service satisfaction and level of anxiety in parents of hearing-impaired children. Seventy-five parents of hearing-impaired children, whose problem was diagnosed during the last year, participated in the study. The mothers were interviewed using satisfaction and anxiety questionnaires. There was no association between level of service satisfaction and parental state and trait anxiety level; however, the group with a higher level of satisfaction (score 64-90) recorded a lower anxiety score (0-20). There was also a significant association between parental state and trait anxiety level (p<0.001). Considering the demographic data, only the living place (Tehran compared with other provinces) showed a significant association with satisfaction and anxiety levels; people living in small provinces had a significantly less satisfaction level (p=0.002) and a more anxiety score (p=0.017). Lack of durability of services was the concern of people living in small provinces which resulted in being more anxious and less satisfied.

One of the chemical pollutions which is frequently common in industry-other than noise is carbon monoxide. The present study aimed to assess the putative protective effect of N-acetylcysteine on the function of outer hair cells of rabbits exposed simultaneously to noise and carbon monoxide.

24 male rabbits are entered in this interventional study. After obtaining baseline distortion product otoacoustic emissions, rabits were randomely devided into four groups. The groups Included: exposed with noise and received saline, exposed with noise and carbon monoxide and received saline, exposed with noise and received N-acetylcysteine, and exposed with noise and carbon monoxide and received N-acetylcysteine. Subsequently, they were evaluated again with distortion product otoacoustic emissions in two stages (two hours and one week after the exposure). Data were recorded and analyzed using paired and independent sample t-tests.

Exposure to noise, and also simultaneous exposure to noise and carbon monoxide, and moreover using N-acetylcysteine in both groups, produced significant changes in distortion product otoacoustic emissions amplitudes (p<0.005).

The findings of the present research reveal that simultaneous exposure to noise and carbon monoxide may potentiate noise induced hearing loss. In addition, utilizing N-acetylcysteine can be used as a preventive agent for noise induced hearing loss and to avoid its potentiation with carbon monoxide.

Speech intelligibility is defined as a measure of effectiveness of understanding speech. It has many applications such as nomination of speech disorder intensity. Different methods and speech tasks have been designed for assessment of speech intelligibility amongst which word identification tasks have high validity. This study aimed to provide a test to measure speech intelligibility among children aged 3 to 5 years old. Many words were collected and content validity was assessed by 9 speech-language pathologists and 1 linguist. Thirty four words with a content validity above 70% were chosen as the test words and the speech-language pathologists collected suitable pictures for the words. One hundred boys and girls aged 3 to 5 years participated in the study. Inter-rater reliability was administered to assess the test reliability. An interclass correlation coefficient of 0.85 and spearman correlation coefficient of 0.81 was obtained for the speech intelligibility test. Speech intelligibility test has appropriate validity and reliability and is suitable for assessment of intelligibility in 3 to 5 years old children.

Learning disability is a term referes to a group of disorders manifesting listening, reading, writing, or mathematical problems. These children mostly have attention difficulties in classroom that leads to many learning problems. In this study we aimed to compare the auditory attention of 7 to 9 year old children with learning disability to non- learning disability age matched normal group. Twenty seven male 7 to 9 year old students with learning disability and 27 age and sex matched normal conrols were selected with unprobable simple sampling. 27 In order to evaluate auditory selective and divided attention, Farsi versions of speech in noise and dichotic digit test were used respectively. Comparison of mean scores of Farsi versions of speech in noise in both ears of 7 and 8 year-old students in two groups indicated no significant difference (p>0.05) Mean scores of 9 year old controls was significant more than those of the cases only in the right ear (p=0.033). However, no significant difference was observed between mean scores of dichotic digit test assessing the right ear of 9 year-old learning disability and non learning disability students (p>0.05). Moreover, mean scores of 7 and 8 year- old students with learning disability was less than those of their normal peers in the left ear (p>0.05). Selective auditory attention is not affected in the optimal signal to noise ratio, while divided attention seems to be affected by maturity delay of auditory system or central auditory system disorders.

Glottic closure pattern is one of the most important stroboscopic signs in judging the normality of laryngeal function. According to the recent researches, complete glottic closure is not the only pattern in normal phonation. The aim of this study was to investigate the glottic closure pattern in normal subjects and to understand the role of sex in having different glottic closure patterns. In a cross-sectional study, 80 subjects (58 females and 22 males; mean age of 21.19 years) were randomly selected from a population of 218 students. After taking a full medical history and performing perceptual and voice self assessment, subjects without any vocal disorders were recruited. Videolaryngoscopic assessment was performed during producing the vowel sound /i/ in habitual, high, low, loud and soft levels of phonation. Glottic closure patterns were analyzed in different phonation and also were compared between males and females. Although complete closure was the most frequent pattern, Y posterior chink was the second pattern in males (20.2%) and females (39.4%) in all phonation. The results revealed significant difference between males and females in glottic closure pattern (p=0.001). Moreover, significant differences were observed in habitual (p=0.004), high (p=0.006) and soft (p=0.02) phonations between males and females; however, the differences in low (p=0.7) and loud (p=0.19) phonations between males and females were not significant. Y posterior chink, as well as complete closure, are likely to be normal findings in people with normal voice. Besides, gender has a significant influence on glottic closure pattern.

valid identification, prevention, and treatment of language disorders are a high priority for the speech and language professionals. One method for studying language development is sentence repetition that is faster to implement and analysis than other procedures. The aim of this project was constructing sentence repetition test as a quick measure of grammatical potency in 2.5 to 4 year old children. Sentences appropriate for 2.5 to 4 year old children were selected during several stages by speech and language pathologist and linguists. The validity of sentences was assessed by professional masters in this theme. Subsequently, 41 sentences including those with 80% high validity were selected as the test sentences. Appropriate pictures were also provided with sentences. The test was administrated to 72 children in 3 groups (2.5-3, 3-3.5, and 3.5-4 year olds, gender matched). The reliability was administered with a test-retest design across a 2 weeks interval. Content validity Index for this test was 80%. "Test-retest reliability” was used for reliability of this test. The Interclass correlation coefficient for this test was 0.95 and standard error measurement was 7.45. The average of scores for sentence repetition, between groups was significant (p<0.001, p<0.001, p= 0.014). This sentence repetition test has the appropriate validity and reliability as well as the capability of proper and quick assessment (screening) of grammatical development in 2.5 to 4 year old Persian speaking children.

Neuroimaging techniques in audiovisual speech processing are innovative approach to neuroscience investigation that steadily influences the deep survey of highly mechanisms involved in this process. The purpose of this study was to evaluate brain activity via functional magnetic resonance imaging throughout audiovisual speech perception in Persian language.

Functional MRI was used to assess 19 normal 20-30 year old women while they had been presented syllable /ka/ visually and /pa/ auditory using block design method, in which it would provide two series of imaging, functional and T1-weighted. Subsequently, the results were analyzed and compared by FSL software.

The results of this study pointed out that both middle and cortical regions of brain are activated in visual stimuli and its middle regions are activated in response to auditory stimuli. Hence, left anterior supramarginal, some parts of motor speech system including insular and cingulate cortex-precentral cortex were stimulated with visual stimulus and left posterior supramarginal as well as right supramarginal gyrus were stimulated with auditory stimulus. Moreover, in this investigation, McGurk effect was behaviorally proven in fifteen subjects.

It was hypothesized that the activation of unique region, supramarginal gyrus, with both audio and visual stimuli indicated the presence of commonplace region for phonologic processing of sensory inputs. In addition, auditory stimuli develop more intense activity; and on the other hand, broaden-maximum voxel-as well as extra regions are demonstrated in response to visual stimuli. These points represent the unfamiliarity of normal individual brain to percept visual speech stimuli.

Conventional balance tests such as electronystagmography and videonystagmography, which are vision-dependant, are not practical in blind patients. Instead, vestibular evoked myogenic potential, not needing any vision, seems to be a more appropriate test for evaluating the vestibular system, in these patients. This study aimed to assess the prevalence and the latencies of p13 and n23 waves among congenitally blind and sighted participants evaluated by vestibular evoked myogenic potential. In a cross-sectional study, vestibular evoked myogenic potential was recorded for 20 sighted and 20 congenitally blind subjects, aged 18 to 30 years old, using 500 Hz-tone bursts (95 dBnHL). Vestibular evoked myogenic potentials responses were present in all (100%) of the participants. Considering the results of the both ears, there was no significant difference between mean p13 and n23 latencies of the two groups (p>0.05). Formation of vestibular evoked myogenic potentials reflex arc and neural pathway in congenitally blind patients is similar to sighted individuals; hence, the development of this pathway is independent of the visual system. Vestibular evoked myogenic potentials test is a useful test to assess vestibular function of the blinds.

N-acetylcysteine, a glutathione precursor and reactive oxygen species scavenger, is reported to be effective in reducing noise-induced hearing loss. Many workers in industry are exposed simultaneously to noise and chemical pollutants such as carbon monoxide. We investigated effectiveness of N-acetylcysteine in protecting the cochlea from simultaneous noise and carbon monoxide damages. Twelve rabbits were exposed simeltaneously to 100 dB sound pressure level of broad band noise and carbon monoxide 8 hours a day for 5 days. One hour before exposure, experimental group received 325 mg/kg of N-acetylcysteine while normal saline was administered for the control group. The protective effect of N-acetylcysteine was evaluated 3 weeks after exposure by histological assessment of the hair cells. Simultaneous exposure to noise and carbon monoxide resulted in a considerable damage to the outer hair cells; however, the inner hair cells and the pillar cells remained intact. Use of N-acetylcysteine in the experimental group significantly reduced the extent of outer hair cell loss. N-acetylcysteine attenuates simultaneous noise and carbon monoxide induced hair cell damage in rabbits.

Hearing impairment is the most prevalent sensorineural defect in human. Epidemiological studies and the following preventive programs are the first steps to save many individuals from being handicapped and non-productive. Hereby, we aimed to study the prevalence of hearing impairment in Ardabil province and to assess the prevalent causes of hearing impairment in Ardabil. In this study, 10718 cases were selected by random cluster sampling from rural and urban population in Ardabil province. Data was gathered using screening questionnaire, normal- and impaired-hearing individual questionnaire, and clinical audiometry. Statistical indices were calculated and data was analyzed using chi-square test. 7.1 per thousand individuals suffer hearing impairment and 4.3 per thousand are deaf. Hearing impairment was significantly more among villagers and aged individuals (p=0.46). However, there was no significant deference between two genders (p>0.05). Our results also showed significant deference in consanguineous marriage (p=0.031), accidents in pregnancy (p=0.007), older age of mother (p=0.007), parents hearing loss, severe illness during childhood (p=0.001), low family income (p=0.004), rural housing and educational level of parents (p=0.001) with hearing impairment. Health status, economical, cultural and educational level of society are the most important factors associated with hearing impairment in Ardabil province. Consequently, extensive preventive programs are required to limit such factors.

Stress is associated with life satisfaction and also development of some physical diseases. Birth of a disabled child with mental or physical disability (especially deaf or blind children), impose an enormous load of stress on their parents especially the mothers. This study compared stress levels of mothers with hearing impaired children and mothers of normal children or with other disabilities. In this study, cluster random sampling was performed in Karaj city. 120 mothers in four groups of having a child with mental retardation, low vision, hearing impairment and with normal children were included. Family inventory of life events (FILE) of Mc Cubbin et al. was used to determine stress level in four groups of mothers. The results of this research indicated a significant difference (p<0.05) between stress levels of mothers with hearing impaired children and mothers of other disabled and normal children in subscales of intra-family stress, finance and business strains, stress of job transitions, stress of illness and family care and family members "in and out''. There was no difference between compared groups in other subscales. Since deafness is a hidden inability, the child with hearing impairment has a set of social and educational problems causing great stress for parents, especially to mother. In order to decrease mother’s stress, it is suggested to provide more family consultation, adequate social support and to run educational classes for parents to practice stress coping strategies.