Hearing Level Comparison of Noisy and Silent Area

This prospective study was carried out in the Department of ENT and Head Neck Surgery, Sheikh Hasina medical college, Tangial, Bangladesh in a period of 6 months from January 2017 July 2017 among those complaining hearing loss attending in ENT out patient department. The aim of the study was to find the out pattern of hearing loss and hearing level comparison between noisy area (such as bazaar, bus stands, factory, school etc) to silent area. In this study 103 cases of hearing impaired people were taken and the data were collected by interviewing the cases as per questionnaire from history, examination and investigation report. Working place of most of the hearing impaired people was in noisy area 88 (85.4%). Among them most of the patients was male (58%) and female was (42%) and male:female ratio 1.4:1. The commonest type of hearing loss was sensorineural type. In the right ear 55 cases (53.4%) of sensorineural type deafness, 19 cases (18.4%) of mixed type of deafness and 21 cases (20.4%) of conductive type deafness. In the left ear 46 cases (47.7%) of sensorineural type deafness, 18 cases (17.5%) of mixed type deafness and 24 cases (23.3%) of conductive type deafness. This study showed that male (58%) were mostly affected than female (42%) and vehicle drivers (25.5%) were commonest group of people. From this study we got both ears were involved by disease process in 77.6% of patients and only right ear was 14.6% and only left ear was 10% of the patient of hearing loss.


Introduction:
The ear disease are common in our country but its diagnosis is usually delayed, till then certain amount of hearing loss occurred. So, awareness, early diagnosis and proper treatment are needed to improve the situation. In Bangladesh a lot of people have different type and degree of hearing impairment. It is one of the important causes that makes a person different from of handicap and detached him from the society 1, 2 . Even a hearing impaired person become a burden of the society. Hearing impairment is such an important issue that a deaf child can not talk.
It is congenital or acquired and according to degree of deafness, it is mild, moderate, moderately severe, severe or profound. According to type of deafness it is conductive, sensorineural and mixed. We had 103 patients were underwent details history, examination and investigation. The WHO estimated in 2005 that there were 278 million people worldwide with bilateral moderate to profound hearing loss, of whom 62 million had deafness that began in child 3-5 . Two-thirds of people with moderate to severe hearing loss live in the developing countries. South East Asia has the largest of hearing impairment in world and houses one-thirds of the hearing impaired population. So it should routinely done in those patients comparing hearing impairment.

Methods:
It was a prospective study, carried out in the department of ENT and Head Neck surgery, Sheikh Hasina medical college, Tangial, Bangladesh from 01.01.2017 to 01.06.2017 for 6 months. Clinically and by investigation that is pure tone audiometry done in Hearing Centre Speech and development, Tangail. proved case of hearing loss were included in the study. 103 cases of hearing impaired people attending in the department of Otolaryngology and Head Neck surgery was the study population. Data collected by interviewing the cases as per questionnaire from history, examination and investigation report of the patients and are presented by various tables and graph.

Operational definitions: i) Tunning fork test a) Rinne test b) Weber test c) Absolute bone conduction test ii) Pure Tone Audiometry:
It is a quantitative test to measure hearing level in different frequency level by Hertz(Hz) and hearing loss level by decibel(dB).
(a) Frequency: It is the number of cycles per second. The unit of frequency is Hertz (Hz) named after the German scientist Heinrich Rudolf Hertz.

(b) Decibel (dB):
It is 1/10th of a bel and is named after Alexander Graham Bell. It is a logarithmic unit and indicates ratio between two different intensities. One dB is equal to the least perceptive difference in sound detectable by human ear in frequencies concern with speech. In the clinical work the threshold of normal hearing is 0 dB.     53.10±14.47. This study is similar to other study [5][6][7] .
In this study out of 103 patients, 60 patients (58.3%) were male and 43 patients (41.7%) were female and male female ratio 1.4:1. The male preponderance also found in other study that the effects of the exposure to occupational noise are larger for males than females in all sub regions and higher in the developing regions 8 .
Out of 103 patients in our study 88 patients (85.4%) were working in noisy area and 15 patients (14.6%) were working in silent area. This study also correlated with other study 9 .
From this study we got both ears were involved 77.7% of the patients, only left ear was 7.8% and only right ear was 14.6%. So both ear (bilateral) involvement were more than unilateral of hearing loss of the patients. It is correlated with the other study 5,11,12,13 .  12,14,15 .
The majority of the persons (62.1%) among the study population had no otological symptoms like hearing loss, tinnitus or vertigo.

Conclusion:
From this study, it can be concluded that a good number of old age people in our country is suffering from sensorineural degree of hearing loss. Most of the people who are working in the noisy area (such as bus stand, bazaar, factory, school etc) that is air polluted area, are those who live in the silent area they are mostly good hearing people.