Background and Aim: phonological awareness skill is an integrated ability that is manifested in 4 skills including syllable, rhyme, and phoneme awareness and alliteration. The aim of the present study is to explore development of syllabic elision skill as an aspect of syllabic awareness.

Methods: It was a descriptive-analytic cross-sectional study. Thirty normal Persian-speaking children, 15 girls and 15 boys, were randomly selected throughout Tehran kindergartens. The participants were monolingual. Children should eliminate a syllable from any word presented, and to state the remaining section of the word. The responses were analyzed using SPSS software.

Results: Ability of 5 to 6 year-old children in eliminating a syllable in two syllabic words was significantly higher than those of three and four syllabic words and syllabic elision of three and four syllable words was significantly different (p=0.000). Two, three and four syllabic task correlations were statistically significant and the correlation between syllabic elision ability and the syllabic construct and the positioning of elision syllable was significant (p<0.05).

Conclusion: Syllabic elision skill blossoms in 5 to 6 year-old Persian-speaking children. The maximum ability of syllabic elision evolves after phonological recoding and after learning reading and writing skills. Syllabic elision ability is also influenced by the syllabic construct and the positioning of elision syllable.

Background and Aim: Rhyme awareness is an important criterion for speech, language and writing processing. In Iran, there is no auditory tasks of rhyme awareness available for assessment of 5-6 year-old Persian-speaking children. The aim of this study was to develop and to evaluate Persian rhyme awareness tasks in 5-6 year-old Persian-speaking children.
Methods: A hundred normal 5-6 year-old Persian-speaking children (50 girls and 50 boys) were randomly selected. The two rhyme awareness tasks of this study were rhyme detection and rhyme production. The validity and reliability of these tasks were studied by content validity index, intraclass correlation coefficient, and standard error of measurement. The correlation between tasks was studied by Pearson correlation and the mean scores of two sections were compared by easiness level method. The comparison of mean scores of girls and boys were evaluated by independent t-test.
Results: The results showed that the proposed tasks had appropriate validity and reliability. The ability of children in production section was significantly more than in detection section. The correlation of each of two sections with total tasks was significant (p<0.05). In addition, the mean scores of girls and boys were not statistically different (p>0.05).
Conclusions: The proposed tasks are appropriate for assessment of rhyme awareness skills with appropriate validity and reliability in both genders. Two Sections of the tasks had significant correlations and influence on together. The abilities of girls and boys were the same.

Background and Aim: One of the chemical pollutions which is frequently common in industry-other than noise is carbon monoxide. The present study aimed to assess the putative protective effect of N-acetylcysteine on the function of outer hair cells of rabbits exposed simultaneously to noise and carbon monoxide.
Methods: 24 male rabbits are entered in this interventional study. After obtaining baseline distortion product otoacoustic emissions, rabits were randomely devided into four groups. The groups Included: exposed with noise and received saline, exposed with noise and carbon monoxide and received saline, exposed with noise and received N-acetylcysteine, and exposed with noise and carbon monoxide and received N-acetylcysteine. Subsequently, they were evaluated again with distortion product otoacoustic emissions in two stages (two hours and one week after the exposure). Data were recorded and analyzed using paired and independent sample t-tests.
Results: Exposure to noise, and also simultaneous exposure to noise and carbon monoxide, and moreover using N-acetylcysteine in both groups, produced significant changes in distortion product otoacoustic emissions amplitudes (p<0.005).
Conclusion: The findings of the present research reveal that simultaneous exposure to noise and carbon monoxide may potentiate noise induced hearing loss. In addition, utilizing N-acetylcysteine can be used as a preventive agent for noise induced hearing loss and to avoid its potentiation with carbon monoxide.

Background and Aim: Evaluation of voice problem involves perceptual, acoustic, aerodynamic and physiological measure. In recent years assessment of patients point of view use as a essential part of evaluation. The aim of this study was construct a questionnaire for assessment of physical, functional and emotional voice problems in adults.
Methods: This study is a kind of constructing battery. Based on a comprehensive study of many foreign questionnaires, "The voice symptoms assessment" questionnaire in adult was produced. Its content validity was determined according to the judgment of 7 speech and language pathologists. This questionnaire administered to 60 voice patients (20 female and 40 male) between 18 to 60 years old that could read and write in Persian. The reliability of this questionnaire is determined by the method of Cronbach Alpha and split half.
Results: Content validity index of this questionnaire was 0.94. Cronbach Alpha was high (more than 0.7) and Spearman-Brown coefficient of split half was 0.96. Correlatoin Coefficient was statistically significant between 3 parts and total questionnaire (p<0.01).
Conclusion: "The voice symptoms assessment" questionnaire in adult has good content validity and reliability and reflects the wide range of physical, functional and emotional problems in voice patients. This questionnaire is simple for patients to complete and easy to score. It seems that use of this questionnaire, as part of a complete voice evaluation will be helpful in future.

Background and Aim: Sound conditioning is exposure to a non-traumatic, moderate level of sound which increases inner ear resistance against further severe noise. In this study, we aimed to survey the effect of sound conditioning on auditory brainstem response (ABR) threshold shifts using click stimulus, and the effect of the frequency of conditioning on hearing protection.
Methods: Fifteen guinea pigs were randomly divided into 3 groups. Two conditioned groups were exposed to 1 kHz, and 4 kHz octave band noise at 85 dB SPL, 6 hours per day for 5 days, respectively. On the sixth day, the animals were exposed to 4 kHz octave band noise at 105 dB SPL, for 4 hours. The control group was exposed to intense noise, 4 kHz at 105 Db SPL for 4 hours (without conditioning). After exposure, ABR thresholds using click were recorded an hour, and 7 days after noise exposure.
Results: The results of the ABR with click stimulus showed less thresold shifts in conditioned groups than control (p≤0.001). Comparison of the results of conditioned groups, showed less threshold shift by 4 kHz conditioning, however, this difference was not statistically significant (p>0.05).
Conclusion: Electrophysiological data of our study showed that sound conditioning has a protective effect against subsequent intensive noise exposure, and the frequency of conditioning does not have significant effect on ABR threshold shifts when using click stimulus.