---

Sound is an inseparable part of human life and provides us with lovely experiences such as listening to music. Musicians from classical orchestras to rock groups are exposed to high decibel of sounds. Musicians playing percussion musical instruments are exposed to high level of impact noise and players of Brass musical instruments are highly exposed to noise peaks higher than 100dB. Woodwind players are enduring the risk of posing directly in front of Brass players. Based on the above-mentioned risks for hearing loss clinical consideration of noise induced hearing loss in musicians is highly required.In the current study we were aimed at examining hearing stratus of classic and traditional musicians by means of pure tone audiometry in Islamic Republic of Iran Broadcasting. 33 subjects were evaluated aged between 22 to 59 years old. Their musical experience was variable between 6 to 45 years.The study demonstrated that most of the musicians in this study suffered bilateral high frequency hearing loss with a notch in the frequency range of 4-8 KHz.

---

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.

---

Objective: To measure external ear resonant amplitude and frequency in children (3-7 years old) and to compare with adult measures.
Method and materials: The external ear resonance peak amplitude and frequency of 63 children 3-7 years old were recorded. All of the children had normal tympanogram and there was no cerumen in external auditory canal. 20 adult of 21-24 years old (10 male , 10 female) were selected in order to compare with children that had normal tympanogram. The tests included : 1-otoscopy 2- tympanometry 3-microphone probe tube test.
Results: The average of resonance peak frequency for children and adult is 4200 Hz and 3200 Hz , respectively. The resonance frequency of children had significantly diffrence with average of resonance frequency in adults. The average of resonance peak amplitude for children and adult is 17.70 dB and 17.17 dB , respectively.
Conclusion: Resonant frequency and amplitude affect the hearing aid prescription and fitting process and calculating insertion gain so, this measures seem should be considered in children hearing aid fitting.

---

Objective: Obtaining the diadochokinetic syllable rates standard among the elementary students in 3, 8, and 19 educational zones in Tehran.
Materials and Methods: 1997 students (980 girls and 1017 boys) randomly selected and examined. Frequency of /pa/, /ta/, /ka/ and /pataka/ in 5 seconds and the number of seconds for producing /pa/, /ta/, /ka/ and /pataka/ for 15 times were recorded for every student.
Results: There is significant difference between means of time and frequency with increasing age. Means of some syllable rates were significantly different between girls and boys.
Conclusion: Mean of syllable frequency was increased and the mean of syllable repetition time was decreased with increasing age. On the whole, boys seems to repeat syllables faster than the girls do.

---

Objective: determining difference limen for Frequency (DLF)in string musicians.
Materials &Methods: This case-control study was conducted on 15 string musicians with musicianship > 10 years (30 ears) and 15 normal hearing subjects (30 ears). They all were male and 20-30 years old. DLF was measured after otoscopy and immitance audiometry and pure tone audiometry.
Results: DLF was significantly different between two groups of case and control. DLF in musicians is less than the normal hearing subjects.
Conclusion: It seems that familiarization with notes results in better DLF in musicians comparing to others.

---

Background and Aim: Human’s voice is observable and measurable like his other behaviours. Investigations have shown that characteristics of voice differ in males and females and possibly in different languages. Clinically, knowing natural voice characteristics is helpful for distinguishing voice pathologies. So the purpose of this study was to measure and compare the fundamental frequency human voice.

Materials and Methods: subjects were young males and females of Iranian Fars, Turk and Kurd races. First the subjects were asked to read some Persian sentences , then their voice samples were analysed by Dr.Speech software.

Results: Fundamental frequency mean is 168±46 Hz and 120±48 Hz for females and males , respectively , which shows significant difference. There is no significant difference between fundamental frequency mean of different races.

Conclusion: There is significant difference between fundamental frequency of males and females , but this difference is not attributable to their mother tongue. Key words: voice, fundamental frequency, Iranian, Fars , Turk , Kurd.

---

Background and Aim: Standard tympanometry provides a valuable tool for evaluating middle ear abnormalities although it often fails to distinguish different pathologies that effect the ossicular chain. Multi-frequency tympanometry (MFT) has made it possible. The aim of the present study was to evaluate the role of MFT for distinguishing chronic middle ear pathologies.
Materials and Methods: This cross-sectional study was conducted on 60 patients. One ear was selected from each patient (60 ears) and were classified into 4 groups according to the type of their middle ear pathology adhesive otitis media middle ear effusion atelectasis and retraction pocket. The following parameters were elicited from MFT: static admittance, resonant frequency, and phase angle. The clinical results were compared with the operative findings.
Results: There is significant difference between resonant frequency and phase angle of 4 groups. No statistical correlation exists between phase angle and resonant frequency. The operative results of MFT are correlated with the operative findings.
Conclusion: The most significant parameter derived from MFT to distinguish between the 4 groups seems to be the resonant frequency.

---

Background and Aim: High frequency audiometry (HFA) provides a valuable tool and optimal index for distinguishing and monitoring many pathologies of the ear. The purpose of this study was to measure the reliability of HFA threshold in children.
Materials and Methods : In this cross-sectional study , 100 normal-hearing children, of 7 to 13 years old, including 50 boys and 50 girls were examined with a Belton 2000 audiometer and Sennheiser HD 250 earphones in Pediatric Clinic  of Audiology Department, Faculty of Rehabilitation of Tehran University of Medical Sciences.
Results: The threshold differences between right and left ears in two test sessions, were not significantly different except for 14 KHz. HFA threshold in two test sessions showed no significant difference in all frequencies between girls and boys but 16 and 20 KHz in right ear and 10 KHz in left ear.
Conclusion : The test-retest thresholds for iudividual ears showed ±0-10 dB SPL for difference at least  in 99.74 % of ears at all frequencies that is clinically reliable and acceptable.

---

Background and Aim: Tinnitus represents the perception of sound without an external stimulus. The prevalence of tinnitus ranges from 3% to 30%. In most cases its etiology is unknown. Tinnitus can be classified as pulsatile or nonpulsatile. Nonpulsatile form is the most common form and almost exclusively subjective in nature.  There is a range of condition attributed to nonpulsatile high frequency tinnitus (acoustic neuroma,  Meniere&aposs disease, ototoxic agents, noise exposure...). There are many studies about form, site, loudness, and frequency of tinnitus and how it can affect the quality of patient life.
Materials and methods: This was a descriptive and analytic study. Thirty-six patients (23 men and 13 women) with mean age 53.1 year old with subjective tinnitus evaluated in pezhvak audiometric clinic in Mashhad .The data consisting of age sex, loudness, frequency form and site of tinnitus. Evaluation of affects of tinnitus on the quality of life and habits was performed with a tinnitus questionnaire (TQ).
Results: Tinnitus was unilateral in 64% of cases right site was more common. Mean  pitch was 7.03 kHz and average loudness was 3.8 dB SPL. SDS was in normal range in all of patients. There was a high frequency sensory neural hearing loss (above the 4 kHz) in most of the patients. The greatest score (60.3%) of TQ related to intrusiveness aspect. Sleep disorder has the lowest score (39/3%). Global score was 52.4%.
Conclusion: Nonpulsatile subjective tinnitus has a broad range of etiology with unknown mechanism in most cases and without any history of underlying disease in a large group of patients. This symptom mostly involves the patients` lifestyle that is intrusiveness aspect in comparison with the other aspects including sleep, hearing and somatic complaints. There is no cure for most patient and more studies are needed in the future.

---

Background and Aim: Analysis of transient evoked otoacoustic emissions(TEOAEs) is of considerable interest due to their close relation with cochlear mechanisms which reveal cochlear function.The particular structure of TEOAEs requires a method with both a satisfactory time and frequency resolution. Among different methods the time –frequency techniques are the most suitable approaches. The aim of this study was to investigate the differences between neonate’s cochlear function and adult’s cochlear function using time –frequency approaches in TEOAEs.

Materials and Method: The data of this cohort study was obtained from a sample of 23 normal neonates, aged between 1-28 days, and 31 normal adults, aged between 18 -25 years.TEOAEs with click stimulus were performed for both ears .The TEOAEs files were investigated in time – frequency transform software in off-line mode. The signal to noise ratio(SNR) and response level (dB) of TEOAEs were analysed.

Results: The reproducibility, SNR and response level in neonates was greater than adults and in both groups there were no significant difference between responses of males and females and of the right and the left ears.

Concolusion: There are differences between neonate’s and adult’s cochlear response. High frequencies responses are stronger in neonate’s cochlea.

---

Background and Aim: Objective measurement is general and acoustic measurements in particular have become a substantial aspect of stuttering assessment during the last few decades. Measurements do not replace the perceptual judgment, but they allow a more precise diagnosis, provide more evidence for therapeutic interventions, and are useful as feedback for patients in therapy. The purpose of this investigation was to compare some adult male stutterers&apos and nonstutterers&apos acoustic features.
Materials and Methods: Adult male stutterers and nonstutterers participated this case-control  study. Their fluent reading of 20 sentences in Farsi, prolongation of  vowels /a/ and /i/, and rhythmic counting from 1 to 20 were analyed with Dr. Speech software.
Results: There were no significant differences between two groups in fundamental frequency (f₀) and standard deviation of f₀ in three speech samples (vowels /a/ and /i/, reading 20 sentences, and rhythmic counting from 1 to 20). No significant difference were between two groups for jitter and shimmer.
Conclusion: Non significant differences between two groups are somewhat due to investigation of this parameters in fluent speech of stutterers  and nonstutterers.

---

Background and Aim:  Among all auditory assessment tools, auditory steady state response (ASSR) is a modern test. Modulation frequency for this test is usually 80 Hz. The purpose of this study, was to examined adult subjects with 40 Hz and 80 Hz ASSR and compare the results.
Materials and Methods: Thirty adult (60 ears) were evaluated by ASSR and PTA test, Results were divided into three groups: normal hearing, mild and moderate sensorineural hearing loss.
Results: In all groups, forty hertz ASSR thresholds were relatively closer to behavioral threshold than those of 80 Hz ASSR(p<0.05). Besides, the more severe hearing loss, the lower the difference between those two thresholds. Correlation coefficients were also higher in 40 Hz ASSR(p<0.05).
Conclusion: Frequency modulation thresholds with 40 Hz are more likely to be closer to the behavioral thresholds. Moreover, it has better results than the thresholds with 80 Hz.

---

Background and aim: Noise pollution is one of the main cause of occupational hearing loss. According to WHO reports in many countries workers have been exposed to 85 - 90 dB noise level. The purpose of this study is to manufacture a sound absorber based on combined recycled polyethylene trephetalat (PET) and polystyrene (PS) with an economical method in order to control of noise pollution
Materials and methods: Sound absorber were made of PET and PS with equal weight percent, polyester fiber, and polyvinyl acetate resine, with five to ten centimeters thick. Sound mean absorption coefficient percents were determined by acoustic impedance tube and compared with those of rock wool.
Results: Mean absorption coefficient percent of  samples with one to five millimeter pore size and ten centimeters thickness was significantly better than those with six to twenty millimeters pore size in 50 to 630, 1250, and 1600 Hz, (p<0.05). In general, samples mean absorption coehicient was significally different from those rock wool (p=0.005).
Conclusion: Recycle polymere absorbers may play an important role in national economics as they are prophylactic to some occupational disease and also are economical.

---

Background and Aim: The voice of human being changes during lifetime with different patterns in males and females. In addition to assessment of changes due to aging, some studies examined the voice changes among various languages and ethnical groups. This study is performed to evaluate the fundamental frequency changes in normal 9-50 year-old Persian (Farsi) speaking individuals.
Methods: In this cross-sectional study, 320 voice samples in normal voiceless environment were recorded. The mean of fundamental frequency of vowels and counting is measured by Dr Speech software (real analysis program). Data analysis was performed by MANOVA test and the profiles of their changes were plotted.
Results: The profile of mean of fundamental frequency changes was different in males and females. The mean of fundamental frequency was equal in both genders until 13 years old and the samples of voice had low pitch (Mean: higher than 200 Hz). MFF after 13 years old significantly decreased in males specially in vowels (p<0.001). The changes in vowels and counting were similar. The mean of fundamental frequency in both genders, between 20-40 years old had  relative constancy.
Conclusion: The mean of fundamental frequency changes of vowels and counting in females and males result from diverse dimensions of larynx and other anatomical differences. Significant changes of mean of fundamental frequency in both genders after 13 years old result from puberty in males. The proportional consistence of mean of fundamental frequency between 20-40 years old is probably due to the uniformity of body in this age range.

---

Background and Aim: Vocal cord nodule is one of the voice disorders causes hoarseness and breathy voice. Voice therapy is one of the treatment approaches. We aimed to find out the effects of voice therapy on vocal acoustic characteristics in these patients.
Methods: In this case series, five women with vocal nodule (14 to 45-year-old) participated in a 9-week voice therapy program developed by Boone. Vocal hygiene and voice practices were measured every day using a questionnaire. Moreover, structure and movements of vocal folds were examined using videolaryngostroboscope by a laryngologist before and after voice therapy to evaluate the effectiveness of program. For collecting voice samples we used sustained /æ/ in comfortable loudness for all patients and data were analyzed using Speech Studio.
Results: After voice therapy, fundamental frequency in four of five subjects were decreased but it was not significant (p=0.225). However, jitter in all of five subjects was significantly decreased (p=0.043). After voice therapy, shimmer in three of five subjects were decreased that was not significant (p=0.345).
Conclusion: Voice therapy can be used for the remedy of acoustic vocal characteristics and elimination or contraction of vocal cord nodule.

---

Background and Aim: Formant structure and vowel space are the most important acoustic characteristics of speech sounds. The purpose of this study was to determine formant frequency and vowel space in six Persian vowels.
Methods: This cross-sectional descriptive-analytic study was performed on 60 Persian students of Tehran University of Medical Sciences (30 males, 30 females) with their age ranging from 18 to 24 years. The subject articulated six Persian vowels in isolation and data was recorded by real-analyzer software. Then, the first three formant frequency of each vowel was determined for each subject. Vowel formant frequency averages were measured separately for each vowel and each gender. Vowel space was plotted. The difference between F0 in two groups was compared by Leven and independent sample t tests.
Results: Maximum and minimum values of F0 in both group was related to /æ/ and /a/ (135 Hz in males and 239 Hz in females) and /i/ (146 Hz in males and 239 Hz in females). Besides, F0 in females was significantly higher than males (p<0.001). Maximum and minimum values of F1 were related to /æ/ and /i/. Furthermore, maximum and minimum values of F2 were related to /i/ and /u/. Maximum and minimum values of F3 were related to /i/ and /u/.
Conclusion: The lowest vowels were /æ/ and /a/ and the highest was /i/. The frontest was /i/ and the backest was /u/. the spreadest vowel was /i/ and the roundest was /u/.

---

Background and Aim: To date, the function of auditory efferent system remains unclear. There is evidence that medial olivocochlear bundle receives descending input from the cortex. In this study, the effect of auditory selective attention on stimulus-frequency otoacoustic emissions (SFOAE) was analyzed to investigate the modification of peripheral auditory system by auditory cortex activity in frequency specific mode.
Methods: Thirty-six normal hearing adult subjects with their age ranging from 18 to 30 years (mean age: 21.9 years) participated in this cross-sectional study. Contralateral suppression of stimulus-frequency otoacoustic emissions was recorded in the right ear at 2 KHz. In order to eliminate the auditory attention, subjects were instructed to read a text. Besides, in order to evaluate the effect of auditory attention on contralateral suppression, subjects were instructed to detect target tones in background noise at 1000, 2000, and 4000 KHz.
Results: A significant increase at contralateral suppression of stimulus-frequency otoacoustic emissions was observed in auditory selective attention conditions (p≤0.001). The largest magnitude of stimulus-frequency otoacoustic emissions suppression was seen at 2 KHz.
Conclusion: The results of this study indicated that the activities of medial olivocochlear bundle enhanced by contralateral auditory selective attention increase the magnitude of stimulus-frequency otoacoustic emissions suppression. In fact, these results provided evidence for influence of auditory cortex on the peripheral auditory system via corticofugal pathways in a frequency specific way.

---

Background and Aim: Voice disorders assess with the help of laboratory equipments and perceptual evaluation. Voice samples involve vowel prolongation, text-reading or conversational speech. In Iran, Rainbow text and Grandfather text, were developed for assessing voice.
Methods: This study was cross-sectional and descriptive-analytical. Mean and fundamental frequency variations range in 120 normal males and females aging from 20-59 years old were studied. Voice samples of reading both texts were gathered and compared.
Results: Mean fundamental frequency in males in Grandfather text was 137.93 with SD 1.2 and in Rainbow text was 135.09 with SD 1.1 (p>0.05), in females Grandfather and Rainbow texts were 206.07 with SD 0.9 and 204.23 with SD 2.1, respectively (p>0.05). Fundamental frequency variations range in Grandfather text in males was 88.10 with SD 0.8 and in females was 116.77 with SD 1.3 and in Rainbow text in males was 90.92 with SD 1.1, in females was 116.08 with SD 1.2 (p>0.05). Mean fundamental frequency of males in each text didn&apost show significant difference in age groups and just in 50-59 age group of the female population showed significant difference. Fundamental frequency variations range didn&apost show significant difference in males and females in both texts.
Conclusion: These two texts were the same in measurement of average and fundamental frequency variations range in adults. Significant difference showed between 50-59 age group of the female population and other groups.

---

Background and Aim: Fundamental frequency (F0) of onset is a reliable acoustic cue of voicing differences in plosive consonants. The purpose of present study was to acoustically analyze of the F0 amount of oral plosive consonants in the initial position of words in cochlear-implanted children and normal hearings.

Methods: In this study, the F0 of onset was measured in the speech production of 47 prelingual deaf children who were cochlear implanted about 61 months before the test (range: 47-76 months, SD: 8.6) and the results were compared with 60 normal hearing children who were 60 months old (range: 49-73, SD: 6.5).

Results: Using repeated measurement tests, it was shown that in all places of articulation, the amount of F0 of onset in voiceless plosives was higher than that of voiced ones, because of the low position of larynx and hyoid bone in voiced plosives. On the other hand, in most cases, the F0 of cochlear-implanted children was lower than that of normal hearings and in voiced plosives, there were significant differences (p=0.005) between cochlear implanted and normal hearing children. There was not any significant difference between the F0 of onset in girls and boys.

Conclusion: In all places of articulation, the mean amount of F0 of onset for voiceless plosives was higher than that of voiced plosives. There was significant difference between F0 of onset in cochlear implanted and normal hearing children.

---

Background and Aim: Non-linear frequency compression is a new feature in hearing instruments compresses the voices of a high-frequency region above a certain cut-off point and transfers them to the lower frequency regions in order to improve the audibility. In this study, we aimed to survey the effect of this feature on the total level of hearing skills of children with profound hearing loss at the age of 3-4 years.

Methods: Twenty two 3-4-years-old children with profound hearing loss were selected with improbable simple sampling. 11 of them had hearing instruments with non-linear frequency compression and 11 had traditional hearing instruments. Tavana test (Jarollahi, 2009) was used to compare the level of hearing skills in these two groups.

Results: Comparison of mean scores of total level of hearing skills in two groups indicated a significant difference (p <0.001). Also, the mean scores of level in all subtests, detection (p=0.022), determination (p=0.005), recognition (p=0.039) and comprehension (p=0.010), showed significant differences.

Conclusion: Using the hearing instruments with non-linear frequency compression would increase the total level of hearing skills in children with profound hearing loss at the ages of 3-4-years and also, in all skill of detection, determination, recognition and comprehension.