Actually, the reference provided details the degrees of hearing loss, not the stages of hearing. There is a distinct difference. This answer will address the degrees of hearing loss, as implied by the context, and then briefly address the process of hearing.
Degrees of Hearing Loss
Hearing loss is generally classified into four degrees, based on the faintest sounds a person can hear:
- Mild: A person with mild hearing loss can typically hear speech in quiet environments but may struggle to hear soft sounds or understand speech in noisy places. (21-40 dB)
- Moderate: A person with moderate hearing loss has difficulty hearing most speech at normal conversational levels. They rely more on visual cues and often need to ask people to repeat themselves. (41-70 dB)
- Severe: A person with severe hearing loss can only hear very loud sounds. Communication primarily relies on sign language, lip reading, or hearing aids with high amplification. (71-95 dB)
- Profound: A person with profound hearing loss may not hear any sound at all. Communication is usually through sign language or cochlear implants. (95+ dB)
The unit "dB" stands for decibels, a measure of sound intensity.
The Process of Hearing (Brief Overview)
While the question likely refers to the degrees of hearing loss, it's important to understand the basic process of hearing, which can be broadly divided into stages:
- Sound Collection: The outer ear (pinna) collects sound waves and funnels them into the ear canal.
- Vibration Transmission: The sound waves cause the eardrum (tympanic membrane) to vibrate. These vibrations are then passed on to three tiny bones in the middle ear (malleus, incus, and stapes).
- Cochlear Conversion: The stapes transmits the vibrations to the cochlea, a fluid-filled, snail-shaped structure in the inner ear. Inside the cochlea, tiny hair cells are stimulated by the vibrations.
- Neural Transmission: The stimulated hair cells convert the vibrations into electrical signals that are sent to the auditory nerve, which carries them to the brain for interpretation.
