Any deviation from the limits of normal hearing is defined as hearing impairment. Hearing sensitivity of each ear is measured separately and the degree of hearing impairment/ hearing loss is generally classified in five categories and additional category-slight hearing loss is added between the normal hearing and mild hearing loss especially when assessing the hearing sensitivity of the young children. Table 1 shows the classification of severity of hearing impairment.
Classification PTA range in dBHL
Normal Hearing -10 to 15
Slight Hearing Loss 16 to 25
Mild Hearing Loss 26 to 45
Moderate Hearing Loss 46 to 55
Moderately – Severe Hearing Loss 56 to 70
Severe Hearing Loss 71 to 90
Profound Hearing Loss 91 and more
Table 1. Classification of hearing impairment severity
Impact of hearing impairment
Consequences of hearing impairment will depend on the ears involved, degree of hearing loss, type of hearing loss and age at onset of hearing impairment. Usually, it is assumed that if hearing impairment is only in one ear, person may not have any serious problems in terms of listening. However, research has indicated difficulty to localize, reduced speech discrimination and lower speech and language development leading to significant effect on educational, linguistic and auditory perceptual development of children.
Degree of hearing impairment is of major factor leading to the negative impact on the social, educational and economical development of the individual. Mild hearing impairment may not place persons in disadvantageous position to hear and communicate but the higher degree of hearing impairment can put the person daily living in a very difficult position as he/she will need some assistance. Generally, people speak while involved in conversation at 65dBSPL. If a person has hearing impairment of 60dBHL or more he/she will find problems in verbal communication. This level of hearing impairment has been equated as 40% hearing impairment as in persons with disability(Full participation, equal opportunity and protection of rights) act 1995. Thus the definition of hearing disabled as stipulated in the PWD Act 1995 is a person who has minimum of 60dBHL of hearing impairment in the better ear in speech conversation frequencies.
…… Reference is taken from “Sfuran”
Govt. of West Bengal