Functional Neurochemistry is one of the fields of studies in the auditory system which has had an outstanding development in the recent years. Many of the findings  in the mentioned field had led not only the basic auditory researches but also the clinicians to new points of view in audiology.

Here, we are aimed at discussing the latest investigations in the Functional Neurochemistry of the auditory system and have focused this review mainly on the researches which will arise flashes of hope for future clinical studies.

Background and Aims: As the hearing aid technology progressively promotes toward replacing analog hearing aids with digital and programmable ones, comparison of the patient satisfaction of those kinds of hearing aids by means of a valuable tool seems so necessary. So, the aim of this study was to compare self-reported benefit of analog, digitally controlled programmable and digital hearing aids for reducing disability caused by hearing impairment in mild to severe sensorineural hearing impaired persons.
Materials and Methods: This cross-sectional study was performed on 90 persons with mild to severe sensorineural hearing loss dividing into three groups: 43 subjects were fitted with digital, 15 with programmable, 23 with analog hearing aids. After pure tone audiometry, Abbreviated profile of hearing aid benefit (APHAB) was completed before and one month after using hearing aids to determine the benefit of them.
Results: Global APHAB mean scores for digital, programmable and analog hearing aids were 49.05, 33.19 and 39.53, respectively. Ease of Communication subscale mean scores were 53.46 for digitals, 37.66 for programmables and 39.09 for analogs. Background noise subscale mean scores for digital programmable and analog hearing aids were 46.36, 25.53 and 35.31, respectively. Global and also both subscale mean scores showed significant difference between digital hearing aids and programmable and analog ones. There was no significant difference between reverberation subscale mean scores of three groups.
Conclusion: It seems digital hearing aids may be more beneficial to reduce disability caused by hearing loss than analog and programmable hearing aids are.

Background and Aim: Asking questions is one of the basic skills for getting information. "What", "Who", "Where", "Why", "How much", "How, etc. are question words frequently used for asking questions. Studies on the sequence of acquisition of question words in English speaking children follow a unique sequence. "What" is the first question word used by these children. We aimed to study whether Persian speaking children follow a unique pattern in the acquisition and use of question words as well.
Case: Two normal Persian speaking children (a boy and a girl) who were sent to the kindergarten of Faculty of Rehabilitation Sciences, Iran University of Medical Sciences by their parents were investigated. Children's spontaneous speech from 12 to 36 months was videotaped, and question words were extracted from phonetic transcription of both children's speech. In order to ask a question, both children initially used rising tone with /m/ or /hum/ before saying the first question word. Two first question words were "what" and "where" in both children's speech samples. Asking about the time with the question word /when/ was not appeared in their speech samples until 36 months. These two Persian speaking children also used Wh-question sequentially.
Conclusion: The result of this study was consistent with the results of other studies on English speaking children.

Background: Children usually produce their first words when they are 10-15 months old and go through simple to complex speech by passing some stages. One of the criteria for examining development of children's language is mean length of utterance (MLU). The main purpose of this study was calculating mean length of utterance and grammatical morphemes used by Farsi-speaking children during their 12-60^th months of life.
Case: It was a longitudinal descriptive study. Every month during children's 12 to 60^th months of life, 120-minute spontaneous speech samples of two children in kindergarten were videotaped and transcribed. The girl said her first word at the age of 12, and the boy said his first word at the age of 16 months. Combining words and constructing two-word utterances started at 18 and 20^th months of the girl's and the boy's lives respectively. First grammatical morpheme appeared before the 24^th month of children's lives and when mean length of utterance was lower than 2 morphemes. Singular verb suffixes were acquired sooner than the plural ones. Both children started using six subject identifiers of Farsi language before 36^th month of their lives.
Conclusion: The speech development in Farsi-speaking children follows the same pattern as other children, starting from one-word utterances and complicates gradually by increasing the number of words, word combinations and using grammatical morphemes. The important point is that Farsi-speaking children started to use grammatical morphemes when their mean length of utterance was lower than two morphemes.

Background and Aim: Hearing-impairment leads to problems in language perception which in turn results in difficulties in language production. The present study investigated hearing-impaired children&aposs ability to discriminate Persian vowels. It aimed to describe the extent to which children have difficulty comprehending and discriminating phonetic features of vowels.
Methods: To fulfill this aim, a researcher-made test, which was based on the Auditory Perception Test 2001, investigated the phonetic discrimination of vowels in Persian-speaking and hearing-impaired children aged five to eight years. The test has two sections, auditory-visual and just auditory discrimination of vowels, which included five subtests assessing discrimination of front and back vowels. Through this test, the phonetic discrimination ability of 22 hearing-impaired children was evaluated. The gathered data were analyzed using matched t-test and repeated measures ANOVA.
Results: The findings showed that there is a significant difference between correct responses to the sections on front and back vowels (p<0.05). The audio-visual test showed that the /â/ vowel is easier to discriminate than other back vowels. Moreover, in the auditory test the /â/ vowel had the highest mean. The audio-visual test showed that the /i/ vowel is easier to discriminate than the other front vowels (/e/ /æ/). However, the discrimination of front vowels in the auditory test was the same.
Conclusion: The results revealed that back vowels were more easily discriminated than front vowels by hearing-impaired children.

Background and Aim: Hearing impairment is one of the most stressful disabilities. The mental health of parents caring for children with hearing impairment is at risk. Therefore, technical support and intervention are very valuable for these families. These services are also useful for children’s development. The aim of this study was to assess the effectiveness of social work services on the social adjustment of parents of children with hearing impairment.

Methods: In this study, 37 parents of children with hearing impairment were selected as the sample population. Interviews and case studies were conducted to determine whether the parents were receiving social work services. The social adjustment scale was used to assess parents’ social adjustment. Analysis of variance (F) was used to analyze the data and information obtained from parents.

Results: Data analysis showed that there is a significant difference between parents who had received social work services and parents who had not received social work services (p<0.001).

Conclusion: According to the obtained results, parents who had received social work services experienced higher social adjustment. It can be said that providing assistance to parents of children with hearing impairment can improve their social integration.