Audiology

Auditory neuropathy: Findings of behavioral, physiological and neurophysiological tests

Mohammad Farhadi

Background and Aim: Auditory neuropathy (AN) can be diagnosed by abnormal auditory brainstem response (ABR), in the presence of normal cochlear microphonic (CM) and otoacoustic emissions (OAEs).The aim of this study was to investigate the ABR and other electrodiagnostic test results of six patients suspicious to AN with problems in speech recognition.
Materials and Methods: this cross sectional study was conducted on 6 AN patients with different ages evaluated by pure tone audiometry, speech discrimition score (SDS) , immittance audiometry , electrocochleography , ABR, middle latancy response (MLR), late latency response (LLR), and OAEs.
Results: Behavioral pure tone audiometric tests showed moderate to profouned hearing loss. SDS was so poor which is not in accordance with pure tone thresholds. All patients had normal tympanogram but absent acoustic reflexes. CMs and OAEs were within normal limits. There was no contralateral suppression of OAEs. None of cases had normal ABR or MLR although LLR was recorded in 4.
Conclusion: All patients in this study are typical cases of auditory neuropathy. Despite having abnormal input, LLR remains normal that indicates differences in auditory evoked potentials related to required neural synchrony. These findings shows that auditory cortex may play a role in regulating presentation of deficient signals along auditory pathways in primary steps.

Reliability of high frequency audiometry threshold in children

Nematollah Rouhbakhsh

Background and Aim: High frequency audiometry (HFA) provides a valuable tool and optimal index for distinguishing and monitoring many pathologies of the ear. The purpose of this study was to measure the reliability of HFA threshold in children.
Materials and Methods : In this cross-sectional study , 100 normal-hearing children, of 7 to 13 years old, including 50 boys and 50 girls were examined with a Belton 2000 audiometer and Sennheiser HD 250 earphones in Pediatric Clinic of Audiology Department, Faculty of Rehabilitation of Tehran University of Medical Sciences.
Results: The threshold differences between right and left ears in two test sessions, were not significantly different except for 14 KHz. HFA threshold in two test sessions showed no significant difference in all frequencies between girls and boys but 16 and 20 KHz in right ear and 10 KHz in left ear.
Conclusion : The test-retest thresholds for iudividual ears showed ±0-10 dB SPL for difference at least in 99.74 % of ears at all frequencies that is clinically reliable and acceptable.

Auditory site of lesion in infants suffering from hyperbilirubinemia by using ABR and TEOAEs

Mehdi Akbari

Background and Aim: Hyperbilirubinemia is one of the most common abnormalities during the neonatal period. Approximately 60% full-term and 80% preterm neonates suffer from hyperbilirubinemia. Hearing loss is one of the most prevalent side-effects of hyperbilirubinemia. This happens when the serum concentration of indirect bilirubin increases dramatically. The main purpose of this study is to evaluate the hearing status and to diagnose the probable site of lesion in affected children.
Materiads and Methods: In this cross-sectional study, 33 newborn to two year old subjects uffering from hyperbilirubinemia were evaluated using auditory brainstem response (ABR) and transient evoked otoacoustic emissions (TEOAE) tests In the Audiology department of the Faculty of Rehabilitation Sciences Iran University of Medical Sciences sampling method was accessible.
Results: 21% of the subjects had severe to profound hearing loss and 9% of subjects had mild to moderate hearing loss. In 51% of the subjects there was no response to ABR and TEOAE tests indicating cochlear and/or retrocochlear lesion. The other 15% manifest only abnormal ABR test indicating the presence of the auditory neuropathy.
Conclusion: TEOAEs test has its own limitations in these subjects, that is the hearing status of such patients can not be completely evaluated by using just TEOAE test. Therefore, to detect hearing loss both ABR and TEOAE tests must be performed in these subjects.

Role of multi-frequency tympanometry in diagnosis of chronic middle ear ventilation problems

Mohammmed Ebrahim Shabana

Background and Aim: Standard tympanometry provides a valuable tool for evaluating middle ear abnormalities although it often fails to distinguish different pathologies that effect the ossicular chain. Multi-frequency tympanometry (MFT) has made it possible. The aim of the present study was to evaluate the role of MFT for distinguishing chronic middle ear pathologies.
Materials and Methods: This cross-sectional study was conducted on 60 patients. One ear was selected from each patient (60 ears) and were classified into 4 groups according to the type of their middle ear pathology adhesive otitis media middle ear effusion atelectasis and retraction pocket. The following parameters were elicited from MFT: static admittance, resonant frequency, and phase angle. The clinical results were compared with the operative findings.
Results: There is significant difference between resonant frequency and phase angle of 4 groups. No statistical correlation exists between phase angle and resonant frequency. The operative results of MFT are correlated with the operative findings.
Conclusion: The most significant parameter derived from MFT to distinguish between the 4 groups seems to be the resonant frequency.

Benefit of analog, programmable and digital hearing aids

Jamileh Fatahi

Background and Aims: As the hearing aid technology progressively promotes toward replacing analog hearing aids with digital and programmable ones, comparison of the patient satisfaction of those kinds of hearing aids by means of a valuable tool seems so necessary. So, the aim of this study was to compare self-reported benefit of analog, digitally controlled programmable and digital hearing aids for reducing disability caused by hearing impairment in mild to severe sensorineural hearing impaired persons.
Materials and Methods: This cross-sectional study was performed on 90 persons with mild to severe sensorineural hearing loss dividing into three groups: 43 subjects were fitted with digital, 15 with programmable, 23 with analog hearing aids. After pure tone audiometry, Abbreviated profile of hearing aid benefit (APHAB) was completed before and one month after using hearing aids to determine the benefit of them.
Results: Global APHAB mean scores for digital, programmable and analog hearing aids were 49.05, 33.19 and 39.53, respectively. Ease of Communication subscale mean scores were 53.46 for digitals, 37.66 for programmables and 39.09 for analogs. Background noise subscale mean scores for digital programmable and analog hearing aids were 46.36, 25.53 and 35.31, respectively. Global and also both subscale mean scores showed significant difference between digital hearing aids and programmable and analog ones. There was no significant difference between reverberation subscale mean scores of three groups.
Conclusion: It seems digital hearing aids may be more beneficial to reduce disability caused by hearing loss than analog and programmable hearing aids are.

Incidence of hearing abnormality in neonate hospitalized in neonate intensive care unit

Mohammad Mahdi Ghasemi

Background and Aim: Risk factors including asphyxia , meningitis , form of delivery, etc. may cause hearing loss in neonates results in speech and language deprivation , emotional and educational problems. The aim of this study was to determine the prevalence of hearing loss and its relationship with risk factors among neonates hospitalized in neonate intensive care unit (NICU).
Materials and Methods: It was a cross-sectional study on 234 NICU hospitalized neonates in Ghaem and Imam-Reza hospitals of Mashhad. Epidemiologic and pathologic information were obtained. Otoacoustic emissions were done in all of neonates. Patients referred to the second otoacoustic emissions (OAEs) and patients failed in the second test controlled by auditory brainstem response (ABR).
Results: Hearing abnormality was found in 11 neonates (4.7%) including 2 girls and 9 boys. (1 neonate with mild, 2 with mild to moderate, 2 with moderate to severe, 1 with sever to profound hearing loss and 4 with auditory neuropathy). Hearing abnormality has a significant greater incidence in group with apgar £5 and in patients with icterus (in need with transfusion).
Conclusion: Incidence of hearing loss in NICU hospitalized neonates are greater in comparison with general population. It has a greater incidence in group with icterus (in need with transfusion) and apgar £5,so,a comprehensive hearing screening program must be applied for early identification and intervention.

Fundamental frequency in males and females voice from Iranian , Turk, and Kurd race

Ali Ghorbani

Background and Aim: Human’s voice is observable and measurable like his other behaviours. Investigations have shown that characteristics of voice differ in males and females and possibly in different languages. Clinically, knowing natural voice characteristics is helpful for distinguishing voice pathologies. So the purpose of this study was to measure and compare the fundamental frequency human voice.

Materials and Methods: subjects were young males and females of Iranian Fars, Turk and Kurd races. First the subjects were asked to read some Persian sentences , then their voice samples were analysed by Dr.Speech software.

Results: Fundamental frequency mean is 168±46 Hz and 120±48 Hz for females and males , respectively , which shows significant difference. There is no significant difference between fundamental frequency mean of different races.

Conclusion: There is significant difference between fundamental frequency of males and females , but this difference is not attributable to their mother tongue. Key words: voice, fundamental frequency, Iranian, Fars , Turk , Kurd.

The effects of increasing the stimulus rate on auditory brainstem response latency in old population with normal hearing

Massoumeh Roozbahani

Background and Aim: The auditory system changes by increasing age in both central and peripheral parts. The purpose of this study was to investigate the effect of the increasing the stimulus rate on auditory brainstem response (ABR) waves latency in old population with normal hearing.
Materials and Methods : In this cross-sectional study click ABR test performed on 20 young normal-hearing subject with mean age of 20.8 years old and 10 old normal-hearing subject with mean age of 66.4 years old. ABR results with different stimulus rates were compared between two group.
Results : ABR peak latencies and interpeak intervals were prolonged with increasing the click repetition rate. Peak latencies were slightly prolonged in older adults and the I-V interval did not differ with age but prolongation of III-V interval were significantly differs in older population compared to young adults.
Conclusion : Using high click rates may sensitize the ABR to the identification. of lesions of auditory nerve or brainstem , but before that , we need to know the normal range of different age groups , so that we can decide about probability of a retrocochlear lesion.

The effect of music on hearing of string musicians

Parisa Mirhaj

Background and Aim: Hearing sensitivity is so vital for musicians as loud music can cause hearing loss. The aim of this study was to assess hearing sensitivity of musicians in order to determine the effects of music exposure on hearing organ.
Materials and Methods: This case-control study was conducted on 15 string musicians with musicianship history of more than 10 years and 15 normal hearing subjects. They all were male and 20-30 years old. TEOAEs and DPOAEs performed after otoscopy , immittance and pure tone audiometry in octave frequencies between 250 to 16000 Hz.
Results: There is not significant difference between pure tone thresholds of two groups for all frequencies.A significant difference of TEOAE is found between two groups for total response and amplituds of TEOAEs . DPOAEs amplituds are not significantly different between two groups .
Conclusion: Musicianship may affect TEOAEs amplitudes , but cannot affect results of PTA and DPOAEs. Therefore this can be useful to detect cochlear lesions secondary to music exposure and also as a tool in hearing protection program.