Audiology

Hearing aid and Hair cell

Zahra Jafari

We expect some people benefit more from their hearing aids, but after a while they complain of inappropriate loudness growth. Currently fitting hearing aids based on their loudness growth curves one of the best and most acceptable ways of fitting hearing aids we should study this curve based on the disturbed function of inner and outer hair cells. We should also know that based on which curves can make the growth curve of the damaged cells to normal ones.

Assessment of Electrically Evoked Auditory Brain Stem Response of 30 Implanted Patients with Nucleus Multichannel Cochlear Implant

Naser Akbarlou

Methods and Materials: Investigation of electrically evoked auditory brain stem response (EABR) is a new issue, especially in implanted patients. Experiments were performed in C.I Center of Iranian Institute for Science and research expansion,1996 on 30 implanted patients with 22 spectra and MSP cochlear implant system and 30 normal subjects with the range of 3-33 years.Findings:1- EABR was obtained in the implanted patients.2- Absolute latency of EABR waves is 1-1.5 ms shorter than ABR waves ‘P<0.05).3-Absolute latency of wave V decreases as a function of electric stimulus magnitude (P<0.05).4- No significant difference was observed in IPL Ill-V between ABR and EABR.

Relationship between Kiessling's Procedure and R-N.A.L, P.O.G.O II and Lybarger Procedures in Determining Gain of Hearing Aid

Kamran Heydari Tari

Method and Materials: This cross- sectional analytical survey is carried out in department of audiology, rehabilitation faculty, IUMS, 1997-1998 on 10 normal and 28 sensory damaged ears out of 27,8 to 40 years old male individuals were evaluated according to following critria:Hearing threshold up to 7OdBHL.Normal middle ear status.
Results: There is good correlation between kiessling&aposs procedure and R-N.A.L, P.O.G.O 11 and Lyharger procedures in determining gain of hearing aid in individuals with flat and raising audiogram. There is poor correlation between them in individuals with high frequency sensory hearing loss.
Conclusion: Kiessling&aposs procedure can he used instead of Lyharger, R-N.A.L, P.0.0.0 11 procedures in children, difficult to test and multihandicapped persons who are not able to cooperate in behavioral audiometry.

Study of the Ability of Articulation Index (Al) for Predicting the Unaided and Aided Speech Recognition Performance of 25 to 65 Years Old Hearing-Impaired Adults

Zahra Jaefari

Background: In recent years there has been increased interest in the use of Al for assessing hearing handicap and for measuring the potential effectiveness of amplification system.AI is an expression of proportion of average speech signal that is audible to a given patient, and it can vary between 0.0 to 1.0.
Method and Materials: This cross-sectional analytical study was carried out in department of audiology, rehabilitation, faculty, IUMS form 31 Oct 98 to 7 March 1999, on 40 normal hearing persons (80 ears 19 males and 21 females) and 40 hearing impaired persons (61 ears 36 males and 25 females, 25-65 years old) with moderate to moderately severe SNI-IL The pavlovic procedure (1988) for calculating Al, open set taped standard mono syllabic word lists, and the real -ear probe- tube microphone system to measure insertion gain were used, through test-retest.
Results: 1/A significant correlation was shown between the Al scores and the speech recognition scores of normal hearing and hearing-impaired group with and without the hearing aid (P<0.05) 2/ There was no significant differences in age group & sex: also 3 In test-retest measures of the insertion gain in each test and 4/No significant in test-retest of speech recognition test score.
Conclusion: According to these results the Al can predict the unaided and aided monosyllabic recognition test scores very well, and age and sex variables have no effect on its ability. Therefore with respect to high reliability of the Al results and its simplicity, easy -to- use, cost effective, and little time consuming for calculation, it&aposs recommended the wide use of the Al, especially in clinical situation.

Binaural Hearing and Beamforming in Digital Hearing Aid

Ahmadreza Nazeri

Binaural hearing is an important phenomenon in hearing for human being. Nowadays, the role of binaural hearing in the process of amplification has been focused. Since hearing aids act separately in the process of amplification and hearing, the attentions has been devoted to designing a system for binaural amplification by means of Beam forming which will be explained in more details in the current article.

Hearing Aid and the Real Aspects of Fitting and Evaluation

Khosro Gourabi

Recent studies have been ocused on designing an intelligent system containing binaural fitting. Researchers are mostly aimed at seperating signals from background noise and other disturbing signals. most of such techniques include Digital Signal Processing(DSP). Here we will have a look in this technique.

Hearing Aid Fitting & Electrophysiologic Procedure

Bahram Jalaei

Rehabilitation of deaf individual is one of the important subjects that has attracted attention of many researchers during past centuries. Different opinions have been established in this direction. Electrophysiologic tests were established and developed parallel to developments in rehabilitation. Therefore, opinion of using electrophysiologic test for evaluation and fitting of hearing aid became gradually popular. Ultimately, the electrophysiologic tests are used in evaluation and fitting of hearing aid in two ways:1-Direct way2- Indirect wayIn direct way aided ABR is obtained and special attention is paid to wave V. This technique has many difficulties. Inindirect way, electrophysiologic tests such, ECochG, OAE and ABR, AMLR, ALR and P300 and other objective tests are used, especially in infants and neonates for evaluating the state of hearing. Researches are continuing in this field. It is probable to have aided electrophysiologic responses with speech stimuli in near future.

Comparing Intensity Elicited Maximum Reflex Amplitude between Noise Induced Hearing Loss & Acoustic Trauma at 1 kHz, Contra laterally, and Investigate Relationship between Amplitude and Hearing Impair

Mehrnaz Asadifar

Method and Materials :this cross sectional descriptive and analytic survey was done at Golestan navy hospital in Tehran, between June 1998 and March 1999 on total of 69 male subject (104 ears, ) 50 acoustic trauma & 54 noise induced H.L) between 20 to 40 ears old.
Results:1- The mean acoustic reflex threshold at 1 kHz showed there is no significant difference between two groups.
2- The intensity elicited maximum reflex amplitude at 1 kHz didn&apost produce at a significant linear correlation with subject&aposs age and ear canal volume in both groups.
3- The intensity elicited maximum reflex amplitude in NIHL group wasn&apost shown a significant correlation with ear compliance and gradient.
4- The mean Intensity (SPL) elicited maximum reflex amplitude in NIHL group was more than mean intensity (SPL) in acoustic trauma group.
5- The mean intensity (SL) elicited maximum reflex amplitude in NIHL group was More than mean intensity (SL) in acoustic trauma group.
Conclusion: Acoustic reflex amplitude is reduced for subjects with NIHL compared with acoustic trauma subjects.

Introducing a formulation to interpret the alternate binaural loudness balance test results and studying the possibility of doing it in one step

Sayyed Jalal Sameni

Extract

In this study, we tried to put forward some formulas for interpreting Alternate Binaural Loudness Balance (ABLB) test results by using characteristics of ABLB graphs. Last step of loudness balancing (in dB HL) and thresholds of both ears are considered as formulas variables. The procedure includes: At first, resulting values are put in a formula to obtain type of graph slope. If the slope represents different recruitment (complete, partial or hyper recruitment), the second formula (last test step value ratio) will be used to determine recruitment types. It should be mentioned that in determining exact ABLB test results, ± 10 dB variability must be considered as a test error. As a result, mentioned formulas have not been an exception and this error factor was included in computing them. In next step, we tried to reduce test time which may be considered as a dilemma for test by using this method. Therefore, the test includes only the last step of loudness balancing and the mentioned formulas are used to obtain the test results. At last, the results of this method were compared to the graph procedure for determining their effectiveness.

High-Frequency Threshold (10 - 20 KHz) in Top Grade Ranking Primary School Children

Nematollah Rouhbakhsh

Method and Materials: This cross - sectional survey is carried out in pediatric clinic department of audiology faculty of rehabilitation, TMSU, on spring 1998. 102 top grade ranking children with normal hearing threshold

Results:1- The thresholds were not significantly different at any frequency (P>0.05) in test re-test trials.
2- The test minus re-test threshold for individual ears showed clinically reliable and acceptable range 0-10dB SPL for at least
99.74% of the ears at all frequencies.
3- The threshold differences between right & left cars in two test sessions were not significantly different (P>0.05) except for 14KHz.
4- High- frequency threshold in two test sessions showed no significant difference between girls & boys at all frequencies (P>0.05) (except for 16 & 20 KHz in right ear and 10 KHz in left ear).
Conclusion: This test can be used for evaluation of individual high-frequency threshold in all frequency as test re-tests tria1. Moreover, this test may use as a beneficial tool for monitoring different endogenous and exogenous auditory pathologies.
Consideration: it is found that this research is valid only among situation of this project. Any generalization needs further research.

Development and Evaluation of a Speech Recognition Test for Persian Speaking Adults

Mohammad Mosleh

Method and Materials: This research is carried out for development and evaluation of 25 phonemically balanced word lists for Persian speaking adults in two separate stages: development and evaluation.In the first stage, in order to balance the lists phonemically, frequency -of- occurrences of each 29phonems (6 vowels and 23 Consonants) of the Persian language in adults speech are determined. This section showed some significant differences between some phonemes&apos frequencies. Then, all Persian monosyllabic words extracted from the Mo ‘in Persian dictionary. The semantically difficult words were refused and the appropriate words choosed according to judgment of 5 adult native speakers of Persian with high school diploma.12 openset 25 word lists are prepared. The lists were recorded on magnetic tapes in an audio studio by a professional speaker of IRIB.In the second stage, in order to evaluate the test&aposs validity and reliability, 60 normal hearing adults (30 male, 30 female), were randomly selected and evaluated as test and retest.Findings:1- Normal hearing adults obtained 92-1 0O scores for each list at their MCL through test-retest.2- No significant difference was observed a/ in test-retest scores in each list (‘P>O.05) b/ between the lists at test or retest scores (P>0.05), c/between sex (P>0.05).
Conclusion: This research is reliable and valid, the lists are phonemically balanced and equal in difficulty and valuable for evaluation of Persian speaking adults speech recognition.

Audiological and ontological findings in Acquired Immune-Deficiency Syndrome (AIDS)

Abdolhamid Hossainnia

The human immunodeficiency virus (HIV) is the virus that causes AIDS (acquired immune-deficiency syndrome). Head and neck are the most common sites in contamination with this virus. HIV can affect outer, middle and inner parts of the ear. Changing in the color of the skin, effusion, infection and sudden hearing loss are some types of the audiological and ontological findings in such patients.

The Comparison of Voice Onset Time (VOT) of Stutterers and Nonstutterers

Eiraj Frotan

Timing of speech activities are under fine control of an adult, so that time intervals between the phonemes in spectra of phonemes are less than l0ms.In stutterers temporal features of speech such as VOT (time interval between the release of the burst of consonant and onset of vocal vibration) are not under careful control of them, so causing symptoms of nonfluency.In this cross-sectional analytical- descriptive survey VOTs of stutterers (30M. 7F) in first & third syllables of 18 words, which started with /PTK/ & /bdg/ consonants are measured.Statistics tests and t-test, repeated measures, multiple range tests and coefficient regression.Findings:1- Mean VOTs of first and third syllables of stutterers in comparison with first and third syllables of nonstutterers are significant (VOTs of stutterers are longer than nonstutterers) (P<.05).2- Mean VOTs of first syllable in comparison with third syllable in stutterers and nonstutterers are significant (VOTs of first /cv/ syllables are longer than third /cv/ syllables) (P<.05).3- There is a significant difference between VOTs of consonants in adjacency of different vowels (P