نشریه پژوهش های شنوایی، گفتار و زبان
پیاپی 1 (1392)

Neural encoding of sounds starts from the auditory nerve and moves on to the auditory brainstem. What is less defined is how the brainstem responds to complex stimuli. The current study quantified brainstem encoding of fundamental frequencies and first formant amplitude of the spoken syllable /da/ using periodic frequency-following responses. Auditory brainstem responses to spoken syllables in both ears were monaurally presented under quiet conditions for 48 normal adults (25 female) with a mean age of 22.7 ± 2.05 years. The magnitudes of the sustained periodic frequency-following responses (FFR) were assessed by fundamental frequency, first formant amplitude, and higher frequency harmonics of the first formant. Measures of the FFR components of brainstem response to the spoken syllables were robustly obtained. Responses occurred earlier in right ear presentation than those in left, approaching significance for the FFR second peak (p =. 004). A significant difference in interpeak latency of DE was observed (p =. 019), but not for EF interpeak latency. Right ear presentation evoked greater spectral amplitude for F0, F1, and high frequency harmonic ranges than the left ear, but there were no significant differences between ears. Overall, waveform morphology for both sides was quite similar. It is evident that response elements reflecting F0 and F1 are symmetrically processed in the brainstem, suggesting the pathway is not primed for the prosodic elements of speech.

Formant frequencies change as a function of the movements of the articulators and as a function of changes in the configuration of the vocal tract. Subjects with hearing loss produce vowels using a limited vertical range and reduce the arc of the tongue, leading to vowel formant centralization. The current study compared F2 ratio and formant frequencies to discriminate children with different levels of hearing loss. Recordings of the speech of 40 children ranging in age from 7 to 9 years diagnosed with hearing loss (moderate, moderate-to-severe, severe, profound) and 40 children with normal hearing were acoustically analyzed. The task was vowel production and the words read contained the vowels /a/, /i/, /u/. The audio files were transferred to PRAAT software (version 13.3.5) to record their formant frequencies. The same vowel formant elements were used to construct the F2i/F2u ratios. Data from F1a, F1i, F1u and F2u in groups with normal hearing and hearing loss did not show significant differences. The F2i/F2u ratio (normal-moderate: p = 0.017, normal-moderate-to-severe: p = 0.003, normal-severe: p = 0.000, normal-profound: p = 0.000), F2a (normal-moderate: p = 0.031, normal-moderate-to-severe: p = 0.015, normal-severe: p = 0.023, normal-profound: p = 0.000) and F2i (normal-moderate: p = 0.005, normal-moderate-to-severe: p = 0.000, normal-severe: p = 0.000, normal-profound: p = 0.000) showed significant differences between the normal hearing and hearing loss groups for all levels. The level F2i/F2u ratio performed consistently, but levels F2a and F2i showed decreased performance. The F2i/F2u ratio was more appropriate for determining vowel production in normal hearing and hearing loss groups.

The complexities of processing and effects of individual factors on the encoding of sounds is a feature of brainstem processing. No statistical method, except fuzzy logic modeling, is effective in explaining these complex relationships. The aim of the current study was to explore the behavior of the brainstem in response to complex auditory stimuli using a fuzzy based model. Auditory brainstem responses to synthetic /da/ stimuli were recorded for 35 normal subjects (17 female) with a mean age of 22.7 years. A fuzzy based model with a Singleton fuzzifier, Mamdani product inference engine, and a center average defuzzifier were used. By providing recorded responses to create a rule base, the behavior of the brainstem was modeled. It appears that, using the training data, the current fuzzy model robustly anticipated and modeled the behavior of speech-evoked responses in the test data set. A mean error of 16.84% (variance: 1%) was observed for 5 randomly chosen training and testing data sets. Auditory brainstem responses to complex sounds (here; spoken syllable /da/) can be modeled using a fuzzy rule base. By correctly extracting these rules from the responses of subjects with normal hearing, a model was established that could anticipate the signals.

Because speech and language development occurs early in life, the age at which hearing loss is diagnosed and cochlear implantation occurs affects speech clarity and comprehension in children with severe to profound hearing loss. The present study investigated the correlation between the age hearing loss is diagnosed and cochlear implantation and the characteristics of children and parents with the level of progress these children experience in aural rehabilitation programs. The study investigated the records of 62 pediatric cochlear implant recipients before and after surgery. Patients had a mean age of 4.71 years (standard deviation = 2) and had undergone cochlear implant surgery at Khalili Hospital in the city of Shiraz, Iran between 2003 and 2011. A significant correlation was found between the progress of children in auditory rehabilitation programs and the age hearing loss was diagnosed (p < 0.0001) and cochlear implantation (p < 0.018). There was also a significant difference between the level of education of the parents and the progress of the children (father: p < 0.0001; mother: p < 0.003). There was also a significant difference in the level of progress of children and the existence or non-existence of behavioral problems in the children (p < 0.0001). Early diagnosis of hearing loss, cochlear implantation at an early age, higher education level of parents, and the lack behavioral problems in the children have significant effects on their success in aural rehabilitation programs.

Life skills training is extremely relevant to the social competency of children. The purpose of the present study was to investigate the effectiveness of life skills training on the social competency of hearing-impaired students in middle schools in the province of Tehran. The present research was an experimental study with a pre-test and post-test design and a control group. The participants were 40 male students with sensori-neural hearing in the range of 35 to 69 decibels. They were selected from grades two and three of all middle schools in Tehran using an available method. Subjects were randomly divided into experimental and control groups, each group consisting of 20 students. The experimental group received 9 sessions of life skills training and the control group did not. Testing was done using the Wechsler intelligence scale for children and the social competency questionnaire. The data were recorded and statistically analyzed using MANOVA. The results of MANOVA showed that life skills training had a significant effect on the social competency of hearing-impaired students (p < 0.001). The results also revealed that life skills training had a positive and significant effect on all subscales of social competency in these students: cognitive skill (p < 0.01), behavioral skill (p < 0.05), emotional competency (p < 0.01) and motivational sets (p < 0.01). Life skills training can improve the social competency of hearing-impaired students. It is recommended that planning life skills training programs for hearing-impaired students receives serious attention.

Teachers use their voices more than do other professionals. This occupational circumstance makes them more prone to voice disorders in comparison with other groups. The purpose of this study was to determine voice handicaps in teachers with voice complaints and to study the correlation between VHI and patient age and years teaching. This was a cross-sectional descriptive-analytical study. Forty female teachers in Tehran primary schools with voice complaints participated. Background information was gathered by interview and a VHI was completed for each subject. Shapiro-Wilk was used to determine normality and the Spearman correlation was employed to evaluate the correlation between VHI and subscales by age and years teaching. All teachers with voice complaints had total and subscale voice handicap scores for VHI. There was a significant correlation between total and subscale scores of VHI by age and years teaching (p > 0.05). The findings indicate that teachers with voice complaints had total and subscale voice handicap scores for VHI. As age and years teaching increased, the voice handicap increased. This finding indicates that for teachers with voice complaints, there is a decrease in voice-related of quality of life and points toward the need for multilateral treatment with an emphasis on quality of life for teachers.

Beta thalassemia major (BTM) is the most common genetic anemia and requires frequent blood transfusions to treat chronic hemolyzation. Desferrioxamine (DFO) is used for BTM patients to decrease the iron in the blood. One side effect of DFO is sensorineural hearing loss (SNHL). This research determined the amount of hearing loss in BTM patients. This was an analytic-descriptive study where all patients (73) surveyed had been referred to the Thalassemia Center of Yazd province. The patients were evaluated for audiometry (HL = hearing threshold ≥ 20 dBHL) and tympanometry in Shaheed Sadoughi Hospital in the city of Yazd. The variables tested were age, sex, dosage and length of treatment. Data was collected and analyzed using SPSS software. In this survey, of the 73 cases (146 ears), 63.01% (46 people) had hearing loss (86.95% SNHL). The results of the tympanometry test showed that 91.8% ears had type AN. There was a statistically significant difference between hearing loss (HL) and dosage of DFO at frequencies of 2000 Hz in the left ear (p = 0.02) and a significant difference between HL and length of treatment at frequencies of 250 Hz in the right ear (p = 0.049). At high frequencies (8000 Hz), there was a significant difference for HL in both ears. There was statistically significant difference between sexes (more males than females showed HL). In this study, the findings are indicative of DFO contribution to the development of hearing impairment in BTM patients. Regular audiologic evaluation is imperative for all thalassemia patients so that early changes may be recognized. The results of this study suggest that the length of treatment and dosage of DFO should be monitored to prevent HL.

Parkinson’s disease (PD) is the second most common neurodegenerative disease. It affects the voice sooner and more severely than the other speech subsystems. This study investigated the relationship between disease duration (DD) and disease severity (DS) using acoustic voice characteristics (AVC) in Iranian patients with PD. This study was carried out on 23 PD subjects (12 male, 11 female) and 23 healthy subjects. DS was evaluated according to the unified Parkinson’s disease rating scale (UPDRS-III) and Hoehn and Yahr (H&Y) evaluation during medication treatment by a neurologist. AVC consisted of average fundamental frequency (F0), standard deviation of F0 (sdF0), minimum and maximum F0 (minF0, maxF0), mean percentage of jitter, shimmer, and harmonic to noise ratio (HNR) was evaluated for /a/ prolongation. Disease duration was related for all patients for F0, sdF0, minF0, maxF0, and female F0 and shimmer. There was no correlation between DD and DS (UPDRS-III) for all patients of both sexes. There was a positive correlation between H&Y and DD for all PD subjects (r = 0.557, p = 0.003) and females (r = 0.606, p = 0.037). H&Y correlated with F0, minF0, and maxF0, but no relationship was found between UPDRS-III and AVC. There is an increased influence on laryngeal signs by PD for F0 and its variations. The duration of the disease is related to disease severity but its relationship with motor disabilities needs more investigation.