Types of deafness
According to the International Bureau of Audiofonology (BIAP), hearing impairments are largely linked to a loss of perception of sounds and speech in particular that contains high-pitched sounds and low sounds whose acoustic power is variable, therefore it can not be reduced to an average acoustic level. According to this, the following category is established:
The average tone loss does not exceed 20 dB. It is eventually a slight loss of tone without social impact.
The average tone loss is between 21 dB and 40 dB. Speech with a normal voice is perceived, however it is difficult to perceive with low or distant voice. The majority of familiar noises are perceived.
First grade: The average tone loss is between 41 and 55 dB.
Second degree:The average tone loss is between 56 and 70 dB.
Speech is perceived if the voice is raised a little. The subject understands better if he looks when they speak to him.
First grade: The average tone loss is between 71 and 80 dB.
Second degree: The average tone loss is between 81 and 90 dB.
Speech is perceived with a strong voice near the ear. The loud noises are perceived
First grade: The average tone loss is between 91 and 100 dB.
Second degree: The average tone loss is between 101 and 110 dB.
Third degree: The average tone loss is between 111 and 119 dB. No perception of the word. Only very powerful and strong noises are perceived.
In case of not perceiving anything at 120 dB or higher, it is categorized as a total hearing impairment.