Degree, type and configuration of hearing difficulty
Updated: Feb 21, 2020
Hearing thresholds are measured in decibels and are plotted on an audiogram for frequencies from 250Hz to 8000Hz. Thresholds are explained using descriptors related to severity (audiogram showing severity of hearing loss - read what's an audiogram):
normal hearing (up to 20 dB HL),
mild hearing loss (21 to 40 dB HL),
moderate hearing loss (41 to 70 dB HL),
severe hearing loss (71 to 95 dB HL),
profound hearing loss (96 dB HL or greater).
Type of hearing difficulty (the origin/source of the problem)
Hearing difficulties may be described as conductive, sensorineural or mixed. This section refers to the part/s of the ear which cause your hearing difficulties.
A conductive hearing difficulty is one that affects the structures that conduct the sound to the inner ear - this includes both the outer and middle ear.
Conductive hearing difficulty can be caused by wax build up, fluid in the middle ear, perforated eardrum or damage to the middle ear bones. Build-up of earwax can easily be removed. See ear hygiene and earwax removal. You will generally need to be referred to an Ear Nose and Throat consultant to treat the other types of conductive hearing loss - an infection can be treated with antibiotics, a ruptured eardrum can be surgically patched and damaged middle ear bones can be surgically replaced or reconstructed.
A sensori-neural hearing difficulty is one that affects the structures that transfer sound from the main organ of hearing (cochlea), to the hearing nerve (auditory nerve), which then conducts sounds to the brain (central nervous system).
Sensory hearing difficulty originates in the inner ear (cochlea) and neural hearing difficulty originates from structures or systems beyond the inner ear (e.g. the auditory nerve or the central nervous system). SNHD is caused by loss or damage to the hair cells in the cochlea. Some common examples of this are:
Age-related hearing difficulty (presbycusis): Many people experience a natural decline in hearing as they get older
Sensory hearing difficulty originates in the inner ear (cochlea) and neural hearing difficulty originates from structures or systems beyond the inner ear (e.g. the auditory nerve or the central nervous system).SNHD is caused by loss or damage to the hair cells in the cochlea. Some common examples of this are:
Viral or bacterial infections: Infections such as mumps or meningitis
Ototoxic Medication: Some medication in high doses such as those for infectious diseases
Other neurological conditions such as dementia, multiple sclerosis, stroke, brain injury or brain tumours affect the brain and/or the central nervous system. This causes hearing difficulty whereby sounds are transferred to the brain but cannot be understood or processed.
Mixed Hearing Difficulty
A combination of conductive and sensori-neural is called a mixed hearing difficulty. This means that the outer, middle and inner ear all affect the hearing.
Configuration of the hearing difficulty (qualitative information)
Gradual / progressive or sudden onset
High frequency or low frequency
Stable or fluctuating
Symmetrical (same level in both ears) or asymmetrical (different level in each ear)
Unilateral (one ear) or bilateral (both ears)