ABSTRACT
Inhibitory function is the basis of many perceptual and non-perceptual abilities in the auditory system. In people with tinnitus, decreased inhibitory function in the central auditory system has been proven. This disorder is caused by an increase in neural activity caused by an imbalance between stimulation and inhibition. The aim of this study was to evaluate and compare inhibitory function in persons who had tinnitus, at and one octave lower than the tinnitus frequency. Studies show that inhibition has very important role in comodulation masking release. According to inhibitory dysfunction in people with tinnitus, in this study we assessed comodulation masking release in tinnitus frequency and one lower octave. Participants were divided into two groups. Group 1 consisted of 7 individuals with unilateral tonal tinnitus at 4 kHz and group 2 included 7 individuals with unilateral tonal tinnitus at 6 kHz. Paired test, in each group separately, showed that the comodulation masking release and Across Frequency comodulation masking release differed significantly between tinnitus frequency and one octave lower in each group (p < 0.05). In fact, the disinhibition in the area around the frequency of the tinnitus seems to be greater than the tinnitus frequency area. It seems that the results of CMRs can be used in planning and managing the treatment of people with tinnitus (such as sound therapy, etc.).
ABSTRACT
In comodulation masking release (CMR), the auditory signal threshold improves when maskers far from the frequency of the target signal are coherently amplitude-modulated. Studies show that inhibitory function may play a role in CMR. In individuals who have tinnitus, decreasing inhibitory functioning in auditory central nervous system has been documented. Therefore, in this study, the purpose was to evaluate CMR in individuals suffering from tinnitus and compare CMR findings with those who do not have tinnitus. Seventeen normal-hearing individuals (without tinnitus) and 13 individuals having unilateral tonal tinnitus (4000 or 6000 Hz) with normal or near to normal hearing participated in this study. All participants were 20 to 50 years of age and underwent comodulated (CM), unmodulated (UM), and reference (RF) threshold measurements and then the CMRs (CMR and Across Frequency CMR; AF-CMR) were calculated. An ANOVA showed that the CM thresholds were statistically different between groups, while the RF and UM thresholds were not statistically different. CMR (CMR & AF-CMR) function was higher in those without tinnitus compared to unilateral tinnitus sufferers. Due to the inhibitory role of the auditory central nervous system in CMR, it appears that tinnitus and CMR both may be influenced by inhibitory function.
Subject(s)
Loudness Perception , Perceptual Masking , Pitch Perception , Tinnitus/psychology , Acoustic Stimulation , Adult , Auditory Threshold , Chronic Disease , Female , Humans , Male , Middle Aged , Young AdultABSTRACT
BACKGROUND AND OBJECTIVES: Detection of auditory signals may be improved when maskers far from the frequency of the target signal are coherently amplitude-modulated. This improvement of signal detection is called comodulation masking release (CMR). In the CMR experiments, flankers have been usually arranged symmetrically. In practice, we will be confronted with a problem by using symmetric flankers due to the limited output of clinical audiometers, especially at high-frequency. We aimed to check whether flanker arrangement has any effect on the amount of CMR, especially when there is no flankers with a frequency higher than the signal. Subjects and. METHODS: Eighteen normal hearing listeners ranging in age from 20 to 46 years old participated. Symmetric (2-2) and asymmetric (3-1 and 4-0) flankers were used and then the amount of CMR compared among them. RESULTS: Our results showed in the same numbers of flankers, there were no statistically CMR differences between symmetric and asymmetric arrangement. Also when we did not have a flanker at a frequency higher than the signal and all flankers were placed below the signal, there was no statistically difference with the symmetric arrangement. CONCLUSIONS: The asymmetry of the flankers and also omitting the flankers with a frequency higher than the signal, have no effect on CMR results. We concluded that CMR can be considered by using clinical audiometer.
ABSTRACT
BACKGROUND: According to willingness of the Ministry of Health, Iran and presence of appropriate conditions for disease elimination, national malaria control program decided to conduct a research to clarify malaria status in 2007 and to provide required information to perform the elimination program. This review is comprised of the basis of national malaria elimination program in vision of 2025, which was started in 2010. METHODS: In this descriptive study, data were analyzed by applications of different variables at district level. All districts in the three south eastern provinces, in which malaria has local transmission, were considered. Malaria cases has been determined and studied based on the national malaria surveillance system. RESULTS: Since vivax malaria is predominant in Sistan & Baluchestan Province, number of vivax cases is equal to malaria positive cases approximately. The important point is that Nikshahr contains the maximum number of local vivax cases in this province and the maximum number of falciparum cases is reported from Sarbaz district. Among all districts of Hormozgan Province, no case of autochthonous falciparum was detected except in Bandar Jask and one case in Minab. There was no case of autochthonous falciparum in Kerman Province, except in Kahnoj and Ghale Ganj that each of them had one case in 2007. CONCLUSION: It appears that the report of locally transmitted cases in Iran is increasing over the past few years, before starting malaria elimination plan. Since the Afghan refugees started to return to their own country so the main source of reporting of imported malaria cases reduced and local cases would be demonstrated more clearly.
