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Search Results: 1 - 10 of 171 matches for " Nariman Rahbar "
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Difference Limen for Intensity Following Monaural Use of Hearing Aid
Mohanna Javanbakht,Nariman Rahbar,Mohammad Kamali
Audiology , 2011,
Abstract: Background and Aim: It is well established that adult sensory systems can reorganize following environmental changes; hearing aid stimulates a deprived auditory system resulting in changes in received stimuli and may be capable of inducing changes within the auditory system abilities such as difference limen for intensity. Hearing aid fitting induces perceptual and physiological modifications. The present study was conducted to evaluate the effects of hearing aid use on the intensity discrimination performance.Methods: The study group consisted of 30 monaural users of hearing aid with symmetrical moderate or moderately severe sensorineural hearing loss in both ears (15 males, 15 females), aged 45-65 years old with the mean of 57.73 and SD of 8.12 years. difference limen for intensity was measured at two frequencies, 500 Hz, 2000 Hz, and two intensity levels (10 dB SL, 40 dB SL). The results of fitted ears were compared with not-fitted ones.Results: The results of the study showed better difference limen for intensity scores at high frequency and high intensity levels. A significant lower difference limen for intensity in fitted ears was observed compared with not-fitted ears (p<0.05), while there was no significant difference between the difference limen for intensity in the two groups at 500 Hz with 10 dB SL intensity (p=0.132).Conclusion: Hearing aid use affects intensity discrimination performance. Besides, perceptual modification following use of hearing aid is confirmed by our study which suggests a possible functional plasticity due to hearing aid use. However, further.
Development and Evaluation a Farsi Language Version of Synthetic Sentence Identification Test in Normal Individuals
Nariman Rahbar,Mohammad Kamali,Jamshid Pourgharib,Akram Kasiri
Audiology , 2006,
Abstract: Background and Aim: Central auditory processing disorders (CAPD) may have a variety of etiologies therefore, performing CAPD tests seem inevitable. Behavioral tests such as synthetic sentence identification (SSI) has gained considerable popularity because of high sensitivity to brainstem and cortical lesions, high diagnostic ability, cost-benefiting, and also limitations of electrophysiologic tests. The purpose of this study was to prepare a Farsi-language version of SSI and to perform a primary evaluation. Materials and Method: Farsi SSI test was made and recorded on CD. Then sixty 20-to 35- year old normal-hearing participants were evaluated in audiology clinic, Faculty of Rehabilitation Sciences Iran University of Medical Sciences in three months. Results: There is no significant difference between scores of Farsi and original versions of SSI. Gender has no significant effect on the scores. Conclusion: According to this results, Farsi SSI is comparable to the original one. It can, therefore, be used in CAPD test battery.
A Study of the Central Auditory Function in Stutters by Masking Level Difference and Synthetic Sentence Identification Tests
Afsaneh Rajab,Nariman Rahbar,Jamshid Pourgharib,Hamid Haghani
Audiology , 2007,
Abstract: Background and Aim: There are evidences that indicate a relationship between auditory processing disor ders and stuttering, and any disorder in the central auditory function can be at least one of the underly ing causes of stuttering. Even though, using the most state of the art radiographic technologies, i.e. MRI, no definitive answer has been given in relative to this question. In this research, using Mask-ing Level Difference (MLD) and Synthetic Sentence Identification (SSI) tests, the central auditory func tion of stutters and normal group was evaluated.Materials and Methods: In this study was analytic cross-sectional, fifteen male patients with stutter-ing and 15 male normal cases with the age range from 16 to 40 years (average age 26.78 year) were evalu ated. SSI-ICM, SSI-CCM and MLD tests were performed. The results were compared in both groups.Results: Although stutterers mean MLD was less than that of normal group, the different was not signifi cant between stutters and normal group in SSI test in right ear at negative MCRs. There was a signifi cant difference in ICM state, but in CCM state, there was no significant difference between the aver age score of two groups in various MCRs.Conclusion: The findings of this research is compatible with those of similar researches about the SSI test and the pattern of results, probably indicates a partial dysfunction of brainstem in some of the stutters.
Comparison of Occlusion Effect in Normal Hearing Individuals and those with Slight and Mild Sensory Neural Hearing Loss Via Real Ear Measurement
Meymaneh Jafari,Nariman Rahbar,Mohammad Reza Keihani,Seyyed Jalal Sameni
Audiology , 2011,
Abstract: Background and Aim: Hearing aid users complain about a phenomenon called "occlusion effect". The aim of this study was to compare the occlusion effect in normal hearing individuals and those with slight and mild sensory neural hearing loss via Real Ear Measurement.Methods: Sixty volunteers (30 male, 30 female) aged 18-55 years were enrolled in this study. Subjects were instructed to vocalize /e/ and /i/ for 5 seconds. Sound pressure level was measured by a probe- microphone and recorded in the ear canal. Occlusion effect and the frequency in which maximum occlusion effect occurs were obtained for each individuals for further analysis.Results: The peak of occlusion effect for /e/ was 10.25 dB and 9.77 dB respectively in 751.9 Hz and 542.98 Hz frequencies in female and male individuals. The maximum occlusion effect occurred with 19.03 dB and 19.10 dB for /i/ and in 518.88 Hz and 440.28 Hz in female and male individuals, in respect. In addition, no significant difference was seen among hearing levels and between genders.Conclusion: The peak of occlusion effect varies significantly among hearing aid users so that the hearing aid must be tuned. Probe-microphone measures will assist in determination where frequency- specific adjustments are needed.
Comparison of Occlusion Effect in Normal Hearing Subjects via Real Ear Measurement and Audiometric Bing Test
Meymaneh Jafari,Nariman Rahbar,Jalal Sameni,MohammadReza Keihani
Audiology , 2009,
Abstract: Background and Aim: One of the most common complaints, particularly among patients with normal or near normal low-frequency hearing, is that their voice sounds "hollow". This is associated with "Occlusion effect". The aim of this study was to comparison of occlusion effect in normal hearing subjects via Real Ear Measurement and Audiometric Bing test. Materials and Method: Twenty volunteers with normal hearing (10 male, 10 female), with ages ranging from 18 – 24 years were enrolled in this study. First, audiometric Bing test was performed in frequencies of 250, 500, 750 and 1000 Hz. Then in real ear measurement, subjects were instructed to vocalize /a/ and /i/ for 5 seconds. Probe microphone was recorded the sound pressure in the ear canals. The degrees of occlusion effect unit were obtained for further analysis.Results: The means of occlusion effect were present in all subjects. There was no correlation between the results of audiometric Bing test and real-ear measurement. No significant difference was obtained between genders and monaural or binaural occlusion in real-ear measurement. But in audiometric Bing test, the difference between monaural or binaural occlusion was significant(p<0.05).Conclusion: The peak of occlusion effect varies significantly among hearing aid users, so the hearing aid must be tuned. Probe- microphone measures will assist in determination how much gain is enough, and where frequency- specific adjustments are needed.
Study of Bone Conduction of MLD Test
Nariman Rahbar,Dr. Mohammad Reza Hadian,Sayyd Aliakbar Tahaei,Dr. Mohammad Reza Keyhani
Audiology , 2000,
Abstract: Materials and Methods: It is for the first time in Iran that designing and construction of phase-shifter instrument for performing Masking Level Difference have been studied. For reducing limitations of MLD test in middle ear pathologies, new methods of performing MLD has been considered. In this method noise is conducted by bone vibrator, located on forehead. The comparison between standard method and proposed method has been obtained. Forty 20-25 year-old men referring to the Faculty of Rehabilitation Science in Iran university of Medical Sciences have been tested in the period of time between 10.30.1998 to 12.21.1998. The MLD test was performed in both method at frequencies of 250, 500, 1000, 2000 & 4000 Hz. Results: The mean of MLD results n the standard method was 11.175 dB ranging from 10 to 13 dB that is in accordance with normative data. There was no significant difference between the means obtained in the methods for performing MLD. In both methods the MLD means decreased with frequency increments. Conclusion: It is preferable to use proposal method in middle ear disorders due to normal cochlear sensitivity and subsequently enough noise that is conducted by bone conduction (60 dB SPL).
Planar Inverted-F Antenna (PIFA) Design Dissection for Cellular Communication Application  [PDF]
Nariman Firoozy, Mahmoud Shirazi
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2011, DOI: 10.4236/jemaa.2011.310064
Abstract: An in-depth approach towards the design of PIFA has been taken. After discussing the essential parameters involved in the design procedure and introduction of a design algorithm, a miniaturized dual-band PIFA is introduced. Different specifications of the proposed antenna are measured both through computer simulation and fabricated PIFA. Also, the Specific Absorption Rate (SAR) is introduced and measured for this antenna.
Braid groups and discrete diffeomorphisms of the punctured disk
Sam Nariman
Mathematics , 2015,
Abstract: Morita proved that for large enough $g$ the mapping class group of a surface of genus $g$, denoted by $\mathrm{Mod}(\Sigma_g)$, cannot be realized as a subgroup of the surface diffeomorphism group $\mathrm{Diff}(\Sigma_g)$, by showing that $H^6(\mathrm{Mod}(\Sigma_g);\mathbb{Q})$ is not a summand of $H^6(\mathrm{Diff}(\Sigma_g);\mathbb{Q})$. Surprisingly, the situation is different for the braid groups. While there is no section from braid groups to diffeomorphism groups of punctured disks, as N.Salter and B.Tshishiku recently showed, we prove that the homology groups of the braid group are summands of the homology groups of the discrete diffeomorphisms of a disk with punctures. This situation is similar to the homeomorphism group of a surface of genus $g>5$ where the mapping class group and the homeomorphism group have the same homology but still there is no section from the mapping class group of such a surface to its homeomorphism groups. Using factorization homology, we also show that there is no homological obstruction to realize surface braid groups by diffeomorphism groups of the punctured surface. We prove that discrete diffeomorphism groups of punctured disks exhibit homological stability and their stable homology is the same as the homology of a certain double loop space. As an application of this method, we also prove there is no homological obstruction to lifting the "standard" embedding of $\mathrm{Br}_{2g+2}$ into $\mathrm{Mod}_{g,2}$ to a group homomorphism between diffeomorphism groups.
Stable homology of surface diffeomorphism groups made discrete
Sam Nariman
Mathematics , 2015,
Abstract: We answer affirmatively a question posed by Morita on homological stability of surface diffeomorphisms made discrete. In particular, we prove that $C^{\infty}$-diffeomorphisms and volume preserving diffeomorphisms of surfaces as family of discrete groups exhibit \emph{homological stability}. We show that the stable homology of $C^{\infty}$-diffeomorphims of surfaces as discrete groups is the same as homology of certain infinite loop space related to Haefliger's classifying space of foliations of codimension 2. We use this infinite loop space to obtain new results about (non)triviality of characteristic classes of flat surface bundles.
Homological stability and stable moduli of flat manifold bundles
Sam Nariman
Mathematics , 2014,
Abstract: We prove that group homology of the diffeomorphism group of $\#^g S^n \times S^n$ as a discrete group is independent of $g$ in a range, provided that $n>2$. This answers the high dimensional version of a question posed by Morita about surface diffeomorphism groups made discrete. The stable homology is isomorphic to the homology of a certain infinite loop space related to the Haefliger's classifying space of foliations. One geometric consequence of this description of the stable homology is a splitting theorem that implies certain classes called generalized Mumford-Morita-Miller classes can be detected on flat $(\#^g S^n \times S^n)$-bundles for $g$ big enough.
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