Asymmetric Flankers in Comodulation Masking Release

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.

Determination of malaria epidemiological status in Iran's malarious areas as baseline information for implementation of malaria elimination program in Iran

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. 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. Since vivax malaria is predominant in Sistan and 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. 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

[Audiological assessment in neonates and children suffering from meningitis]

To assess neonates and children suffering from meningitis , during the critical and recovery periods , using ABR , EOAE and Behavioral Audiometry. 40 neonates to 12-year-old children were assessed. Using ABR test, the hearing of these cases was evaluated during the critical period-that is , 24-72 hours following the diagnosis. This test was repeated when patients recovered from meningitis-that is 24 hours before discharge [recovery period] Hearing function , again , was assessed 7-14 days following discharge through Immittance Audiometry, Behavioral Audiometry [PTA , SF and BOA]. And EOAE [TEOAE and DPOAE] tests procedures. During the critical period , ABR test revealed normal hearing in 35 patients [87.5%] and severe to profound sensorineural hearing loss [unilateral and bilateral] in 5 patients [12.5%-girl=4, boy=1]. The same result were obtained in reevaluation in the recovery period. On the other hand , 7-14 days after of discharge , Immittance Audiometry and Behavioral Audiometry [including PTA , S.F and BOA tests], confirmed the mentioned results [cross - gcheck]. EOAE test [DPOAE and TEOAE] in 35 normal hearing patients [according to ABR test] , showed normal cochlear function. 2 out of 5 cases suffering from severe to profound sensorineural hearing loss revealed normal cochlear function. According to EOAE results , abnormal cochlear function was evident in 3 patients. ABR , EOAE tests , and Behavioral Audiometry in children meningitis during the critical period and recovery period can be used to diagnose any degree of hearing loss with a high level accuracy. The results of persent study is confirmed by previous investigations