One type of hearing loss is conductive hearing loss (CHL) that shows an air-bone gap in the standard audiometry.
1) The sound is affected before entering the inner ear in CHL
2) and leads to some undesirable consequences. The acquired unilateral CHL reduces the ability to localize sound
3) and the affected individuals' life quality.
4) Moderate or even mild hearing loss could be a significant problem for school children
5) because educational listening is not easy in the presence of background noise.
2) Furthermore, a mild hearing loss in children may cause impairments in the development of communication, behavioral skills,
6) learning ability,
7) and speech.
8) Eustachian tube dysfunction,
9) ossicular chain problems caused by head trauma
10) and otitis media (OM) are factors that may lead to CHL. The most common consequence of OM is the hearing impairment,
11) and there are 29 types of OM.
12) Although according to some studies the CHL caused by otitis media can lead to secondary problems such as auditory processing disorder,
2) cognitive, language, speech and behavior problems,
13) there is no strong evidence on the impact of the middle ear effusion on speech and language, so this subject is a matter of controversy.
11) Allergies and environmental factors (seasonality and upper respiratory infections) may also lead to OM. In some studies, OM was more commonly observed during the autumn and winter as against the summer in both northern and southern hemispheres.
14) According to a prospective, longitudinal cohort study in Southern Brazil on 156 children in autumn, winter and spring, using tympanomrtry and otoscopy, the incidence of serous otitis media was higher in winter, especially, among children of lower socioeconomic classes.
15) A retrospective study on 340 infants below 2 years old with recurrent acute otitis media (RAOM), conducted by Cairo University Hospital from May 2011 to April 2012 indicated that winter is an important factor that may cause RAOM.
16) In 2012, Ting, et al.,
17) carried out a multiple database study in Taiwan and reported acute otitis media (AOM) as a prevalent OM among children in spring. A higher resolution rate in summer and a lower resolution rate in autumn were reported by Gordon, et al.
18) prospective study in New York. They monitored the children who were referred to a tertiary medical center over 3 years. There was a positive correlation between resolution rates and average daily temperatures. otitis media with effusion (OME) could change the middle ear morphologically; particularly in the pars tensa.
19) Gram negative bacteria such as pseudomonas can cause chronic suppurative otitis media that is more common in developing countries and in poorer areas of the developed world.
20) Reviewing the audiograms of 164 citizens of Ankara, Turkey, with idiopathic sudden sensory neural hearing loss (ISSHL) over 5 years indicated that ISSHL was more profound in autumn than in summer. Also hearing loss was more profound in winter as against summer and spring. Therefore, the seasonal variation of hearing loss level of ISSHL was more profound in winter.
21) Considering the seasonality as a risk factor for OM,
22) incidence of conductive hearing loss is varied in different seasons because warmth affects the enteric bacteria colonization of chronic suppurative otitis media, and the frequency of isolation of enteric bacteria rises in hot climates.
23) When relative humidity rises up to 80 percent, incidence of otomycosis infection goes higher, and it infects middle and external ears.
24) Dampness is also the most important environmental factor connected with ear infection, since molds have serious effects on humans' immune system.
25)
This study aims at determining and comparing the prevalence of conductive and mixed hearing losses in both summer and autumn among children, juveniles and adults who referred to the Iranian-based audiology center of Imam Khomeini Hospital, in the city of Ahvaz.