Hearing Testing

By Cynthia Beauregard, MA, CCC-A,
Alison Cavanaugh, MS, CCC-A
and Theodore Mason, MD

When a patient expresses concern about hearing, there are a variety of options available to assess and diagnose hearing loss.

A comprehensive audiometric evaluation is the accepted standard of care for individuals with hearing impairment and individuals in whom hearing loss is suspected.  The comprehensive evaluation consists of air and bone conduction thresholds and speech discrimination testing for each ear individually, all of which is done using headphones or insert earphones and in a soundproof booth.  Impedance testing (tympanometry and acoustic reflexes) and otoacoustic emissions (OAEs) may also be included in a comprehensive test battery. A comprehensive audiometric evaluation provides data regarding hearing acuity: the degree of the hearing loss, symmetry, type of loss (i.e. sensorineural, conductive or a combination of the two), configuration (flat, high-frequency, etc.), and the extent to which the loss is affecting one’s daily communication and quality of life. This information is invaluable when determining communicative needs, amplification needs, monitoring hearing sensitivity for changes, and is a necessity for medical intervention.

Conversely, a hearing screening provides only a gross indication of hearing sensitivity. Hearing screenings are a starting point at which we are able to determine patients that are in need of a comprehensive audiometric evaluation. When abnormalities are noted on a screening, a referral for thorough evaluation is required to identify persons who will require further professional management or intervention.  A hearing screening does not provide detailed information about hearing loss as to extent, type or etiology. Where audiometric evaluations are always conducted in sound treated booths, hearing screenings may be conducted in various settings. Therefore, screenings must be interpreted with caution, as their sensitivity and specificity can vary significantly depending on the test environment, equipment used and variances in the tester.  Hearing screenings are most commonly performed on newborns and school aged children.  However, adult screening programs also exist.

HEARING SCREENING – Infants

According to the American Academy of Audiology:

• Hearing loss is the most common developmental disorder identifiable at birth and its prevalence increases throughout school-age due to the additions of late-onset, late-identified and acquired hearing loss.
• Under identification and lack of appropriate management of hearing loss in children has a broad economic effect as well as a potential impact on an individual child’s educational, cognitive and social development.
• The goal of early detection of new hearing loss is to maximize the perception of speech and the attainment of language skills.

Newborns are screened for hearing in the hospital in accordance with the guidelines of the Joint Committee on Infant Hearing.  These screenings guidelines were put into place in the mid-1990s for the purpose of ruling out significant neonatal hearing loss which would have long-term impact on their linguistic, educational, and social/emotional development.  Newborn screenings are performed before the baby is discharged from the hospital by means of a volunteer-administered Automated Auditory Brainstem Response (AABR) or OAE. Infant hearing screening tends to have a fairly high sensitivity and serves as an entry point for more comprehensive Auditory Brainstem Response (ABR) testing. Babies that fail screening will need to be retested by an audiologist.  Unfortunately, a high percentage of infants who fail their newborn screening tend to “fall through the cracks” and do not get their follow-up testing.

HEARING SCREENING- School-aged Children

Children’s hearing is frequently screened at school or at the pediatrician’s office.  Methods for screening may consist of: otoscopy, pure tone screening, tympanometry, and/or OAEs. Each has its benefits and limitations.

• Pure tone screening has a few limitations worth mentioning.  A child that is not cooperative or does not understand the task may not respond appropriately. Ambient noise is a big problem for this screening procedure as it may be very difficult to find a quiet enough area in which to test hearing. A child may not respond, simply because the background noise is so loud it drowns out the test stimuli or prevents the child from staying on task. In addition, the child may be able to cheat by watching the tester’s activity. Also, pure tone testing is affected by middle ear status.
• Tympanometry is an objective measure of middle ear function. Proper insertion of the probe and obtaining a hermetic seal are the first steps of tympanometry.  From there, most machines will run the test for you automatically.  It is important to make sure the probe is facing the ear drum and not the canal wall.
• Otoacoustic emissions (OAEs) have become popular recently, as it is an objective measure of the function of the outer hair cells of the cochlea. The probe equipment emits a sound into the ear that is picked up by the cochlea.  Any functioning outer hair cells in the cochlea will then produce a signal which is then transmitted “backwards” through the middle ear and into the ear canal where it can be picked up by a microphone in the probe in the ear canal. The equipment not only makes a measurement, but it also interprets the results as either a pass or "refer". The child is not required to respond for this procedure to be successful; he/she only needs to be still for a minute or so.

Parental concerns about their child’s speech, language and hearing need to be taken into consideration. Should your screening results display as a pass, but the parents are concerned that their child is not hearing, a referral for a comprehensive audiometric evaluation is required.

HEARING SCREENING- Adult

Adults may encounter hearing screenings in various settings such as the primary care office, at health fairs, at senior centers, or in the workplace as part of a pre-employment evaluation. Unfortunately, in these environments, a screening is misinterpreted by the patient as a comprehensive evaluation, as the screening may not fully represent the true characteristics of the hearing loss. Any abnormalities found on a screening should be followed up by a comprehensive audiological evaluation.

Routine screenings are also conducted as part of an on-going monitoring of hearing in work environments where regular exposure to noise is a factor.  With regard to work place noise, specific federal guidelines/standards are in place which are determined by OSHA or NIOSH which require the annual monitoring of hearing to detect any decrease in hearing thresholds which may indicate that better compliance with hearing protection needs to be encouraged.

Patients that are going to be exposed to a regimen of ototoxic chemotherapy or administered ototoxic antibiotics should ideally be screened before starting therapy and monitored throughout the course of therapy.  Ototoxic chemotherapies have the potential to lead to a permanent, high frequency sensorineural hearing loss. In the case of ototoxic antibiotics, it is difficult to arrest and/or reverse the ototoxicity once treatment has been started; the resulting hearing loss is usually permanent and only occasionally reversible.

Ear, Nose and Throat Surgeons of Western New England employs 6 Master’s Degree or Doctorate level audiologists with extensive experience.  We have 4 sound treated booths and state-of-the-art diagnostic equipment including ABR, OAE, and tympanometry allowing us to provide the community with comprehensive diagnostic and intervention options for patients of all ages.