The difference between a hearing screening and a hearing evaluation is subtle but important.
A screening refers to a single, preliminary test used to determine whether a patient has a hearing loss. Think of it as a pass/fail exam – if the results indicate a hearing loss, a more detailed evaluation is required. Hearing screenings are often conducted through a primary care physician or through school.
A hearing evaluation is an in-depth series of tests conducted by an audiologist used to measure the type, degree and configuration of the impairment and identify the steps necessary for treatment. A typical hearing evaluation consists of: pure-tone audiometry (air and bone conduction), speech testing and middle ear testing (tympanometry and acoustic reflex testing).
The type of hearing loss refers to which part of the hearing system has been damaged. Hearing loss is broken down into three basic types: conductive, sensorineural and mixed.
- Conductive hearing loss occurs when there are problems in the outer or middle ear. This type of hearing loss is structural in nature and can sometimes be treated successfully with medication or surgery. If it is not correctable, hearing aids can often help.
- Sensorineural hearing loss results from damage to the inner ear (cochlea). This type of hearing loss can be thought of as nerve damage and is typically permanent. Common causes are noise exposure, ototoxic medications and genetics. Sensorineural hearing loss is the most common type of hearing loss and can usually be treated successfully with hearing aids.
- Mixed hearing loss is a combination of both conductive and sensorineural hearing losses, meaning both the inner ear and middle ear are affected Depending on the specific cause of the hearing loss treatment might include medications, surgery and/or hearing aids.
The degree of hearing loss refers to its severity. Hearing loss is measured in decibels (dB) and ranges from normal to profound. It is classified as follows:
- Normal -10 to 20 dB
- Mild 21 to 40 dB
- Moderate 41 to 60 dB
- Severe 61 to 80 dB
- Profound 81+ dB
Hearing loss configuration refers to the pattern of loss across frequencies as charted on a patient’s audiogram. For example, a high frequency hearing loss would indicate more hearing loss in the higher pitches. The high pitches impact clarity of speech, whereas low pitches impact overall volume. Other common hearing loss descriptors are:
- Bilateral (hearing loss in both ears) vs. unilateral (hearing loss in only one ear)
- Symmetric (hearing loss is similar in both ears) vs. asymmetric (hearing loss significantly different between ears)
- Progressive (a steady decline in hearing ability) vs. sudden (hearing loss occurs rapidly and without warning)
A full diagnostic assessment is needed to identify the degree, type and configuration of a hearing difficulty. This is a great first step in establishing a treatment plan, which can range from communication strategies to hearing aids.