Fundamentals Of Audiology For The Speech Language Pathologist

What You Actually Need To Know About Hearing Screening In Practice

Most SLP programs skim over audiology in about three lecture periods. Then you walk into a clinic and a parent hands you a child with a referral that says "suspected hearing loss" without any audiogram attached. You have to figure it out from there. I spent years working alongside audiologists before I felt comfortable interpreting a pure tone audiogram without calling them every five minutes. The basics are simple. The edge cases are where people get tripped up. Pure tone audiometry measures the softest sounds a person can hear at specific frequencies, usually tested from 250 Hz to 8000 Hz. The results plot on an audiogram where the vertical axis shows intensity in decibels Hearing Level (dB HL) and the horizontal axis shows frequency. Air conduction tests the entire auditory pathway. Bone conduction bypasses the outer and middle ear to test the cochlea directly. The difference between the two is called an air-bone gap, and it tells you whether the problem is conductive, sensorineural, or mixed. I once had a six-year-old client whose speech sound disorder wasn't improving despite months of therapy. Her audiogram showed what looked like mild sensorineural hearing loss at high frequencies, but the bone conduction thresholds were normal. That air-bone gap at 2000, 4000, and 8000 Hz pointed to a conductive issue, not a neural one. Turned out she had chronic otitis media with effusion that nobody had rechecked in over a year. We got her to an ENT, the fluid cleared, and her articulation accuracy jumped noticeably within weeks. The takeaway is that you should always verify the most recent audiogram yourself rather than trusting whatever was on file from two years ago.

Types Of Hearing Loss And What They Mean For Your Clients

Conductive hearing loss involves the outer or middle ear. Sound can't get through efficiently. Things like earwax impaction, perforated tympanic membranes, otosclerosis, or chronic fluid behind the eardrum cause this. The key diagnostic feature is an air-bone gap of 15 dB or more. These are often medically treatable, which is why collaboration with an ENT matters. Sensorineural hearing loss involves the cochlea or the auditory nerve. Noise-induced damage, genetic factors, Meniere's disease, and auditory neuropathy spectrum disorder fall into this category. Bone and air thresholds are roughly equal on the audiogram, and the loss tends to be flat or sloping toward the higher frequencies. Mixed hearing loss combines both components. The audiogram will show elevated air and bone thresholds plus a persistent air-bone gap. Central hearing disorders involve the brain's ability to process auditory information. Standard audiograms often look normal in these cases, which is why perceptual testing like speech in noise assessments become necessary. Word recognition scores, also called speech discrimination scores, measure how well someone understands spoken language at a comfortable listening level. A person can have what looks like normal hearing on a pure tone test and still score 40 percent on word recognition, which completely changes your clinical approach.

When And How To Refer For Audiology Evaluation

You don't need an audiologist's report to start therapy for many speech sound disorders, but there are hard stops where referral is non-negotiable. Any unilateral hearing loss requires audiology evaluation. Asymmetric results on screening, even a 10 to 15 dB difference between ears, warrant a full diagnostic audiogram. Children who are not progressing in therapy despite appropriate intervention should be re-evaluated for hearing. Adults presenting with sudden or rapidly progressive hearing complaints also need urgent audiological assessment. What most SLPs miss is the importance of checking for recurrent otitis media with effusion in young children. Otitis media with effusion creates fluctuating hearing loss that comes and goes. A child might pass their school screening one month and fail the next because fluid shifted. The average duration of post-acute OME is three months, but it persists in about 24 percent of children at six months and 10 percent at twelve months. If your pediatric client has had multiple upper respiratory infections and their ears haven't been monitored, push for a tympanogram. Pure tone testing alone won't catch this. A type B tympanogram indicates middle ear fluid and is a red flag even when the child responds to soft sounds.

Reading An Audiogram Quick Reference

Normal hearing is defined as thresholds of 25 dB HL or better across all tested frequencies. Mild hearing loss ranges from 26 to 40 dB HL. Moderate falls between 41 and 55 dB HL. Moderately severe is 56 to 70 dB HL. Severe spans 71 to 90 dB HL. Profound is 91 dB HL and above. These categories come from the American Speech-Language-Hearing Association guidelines, and they matter because they influence your treatment planning more than you might realize. A child with mild sensorineural loss at 35 dB at 4000 Hz may appear to hear fine in quiet classroom settings but will miss consonant cues like /s/, /f/, and /th/ that carry high-frequency energy. Those missing cues are exactly the sounds most critical for intelligibility. An adult with the same configuration will report understanding speech but complaining that conversation feels effortful, especially in background noise. The audiogram shows the same numbers either way. The functional impact differs because of cognitive load, linguistic experience, and noise exposure history. You need both the chart and the clinical context.

Tympanometry And What The Patterns Mean

Tympanometry measures middle ear function by varying pressure in the ear canal and observing how much sound is reflected back. The result plots as a peak on a graph where the horizontal axis shows ear canal pressure and the vertical axis shows compliance. Type A indicates normal middle ear function with a peak around zero decapascals. Type As shows shallow compliance, often seen in otosclerosis or a stiff ossicular chain. Type Ad shows excessive compliance, which can indicate a perforated eardrum or ossicular chain disruption. Type C tympanograms show a negative pressure peak, typically around minus 100 daPa or lower. This reflects Eustachian tube dysfunction and is commonly seen before fluid actually accumulates. By the time you see a Type B flat tracing, fluid is usually present. The clinical workflow most clinics follow is pure tone screening first, then tympanometry if anything looks off. Some audiologists reverse that order for pediatric populations because young children tolerate tympanometry quicker than pure tone tasks. Either way, having both pieces of data gives you a complete picture of peripheral hearing status.

Adult Hearing Loss And The SLP Connection

Audiology for the speech language pathologist isn't limited to pediatric populations. Progressive bilateral sensorineural hearing loss in older adults affects roughly one-third of people between 65 and 74 and nearly half of those over 75. The high-frequency sloping loss pattern means these clients hear vowels clearly but struggle with consonant distinction. They respond to questions appropriately in quiet one-on-one settings but become fragmented in group therapy or family sessions. This often gets misattributed to cognitive decline when the real issue is auditory access. I worked with a 72-year-old client with aphasia post-stroke who was making negligible gains in language therapy. She kept nodding along and giving brief appropriate responses. Her WRS score was 56 percent at comfortable levels, which meant she was hearing words but not processing the fine phonological detail. Once she got properly fitted with hearing aids and completed six weeks of acoustic training, her verbal expression output increased significantly. The aphasia hadn't changed. Her ability to access auditory feedback had. Hearing rehabilitation and speech therapy are not separate tracks in this population. They intersect constantly.

Common Pitfalls And Where Beginners Go Wrong

The first mistake is assuming that passing a newborn hearing screening means normal hearing forever. Screening identifies permanent neonatal hearing loss at birth. It does not track developmental changes. Childhood meningitis, head trauma, noisy hobby exposure, and chronic otitis media can all cause acquired hearing loss years after a clean screen. The second mistake is treating a known hearing loss as a fixed variable. Hearing changes. Every six months for children with confirmed loss, annually for adults, and immediately whenever a parent or caregiver reports deterioration. The third mistake is confusing hearing referral with hearing diagnosis. An SLP can identify and should refer, but we cannot diagnose the type or degree of hearing loss. That determination belongs to the audiologist or otolaryngologist. Another frequent error is relying on self-report from adult clients about their hearing. People with gradual high-frequency loss frequently deny having a hearing problem because they can hear well enough in controlled situations. They attribute difficulties to others speaking unclearly rather than recognizing their own sensory deficit. When someone with suspected hearing loss walks into your clinic, ask about TV volume, phone use, and difficulty following conversations in restaurants before assuming everything is fine because their audiogram shows mild loss.

Assistive Technology And Clinical Considerations

Hearing aids amplify sound but do not restore normal hearing. They compress dynamic range, which means soft sounds become audible but loud sounds may become uncomfortable faster. For SLPs, the practical implication is that amplified speech sounds different through a hearing aid. Formant structure shifts. Consonant clarity improves but not to the level of normal hearing. If your client uses hearing aids, test and treat with them in. Removing them strips away the very auditory feedback they use daily. Same principle applies to cochlear implants, though the spectral resolution provided by CI is quite different from acoustic hearing. CI users often perform poorly on frequency discrimination tasks initially and benefit from specific auditory training protocols before standard speech therapy yields optimal results. CROS and BiCROS hearing aid systems route sound from the poorer ear to the better ear. A unilateral hearing loss client wearing a CROS aid will hear on the deaf side but lose binaural localization and the squelch effect that helps filter background noise. Factor this into your recommendation for classroom or group therapy environments. In those settings, a remote microphone system like a FM or digital modulated system provides significantly better signal-to-noise ratio than hearing aids alone. The cost is about 15 to 25 percent improvement in speech recognition in noise compared to hearing aids in reverberant spaces.

What To Do When The Audiogram Doesn'T Match The Clinical Picture

This happens more often than you'd think. A child presents with clear language delay and a borderline normal audiogram. Maybe the pure tones sit at 20 to 25 dB at some frequencies, right at the edge of the normal range. Maybe the word recognition score is unexpectedly low for the degree of pure tone loss. Maybe the behavioral observation and the audiogram disagree. In those situations, the next step is usually a referral for auditory brainstem response testing or middle latency response testing. These objective measures don't require behavioral cooperation and can detect retrocochlear pathology that standard audiometry misses. I encountered a ten-year-old with dysarthria and cerebral palsy whose behavioral thresholds varied wildly between sessions. Sometimes he responded to 15 dB, sometimes not until 45 dB. Pure tone testing relies on consistent behavioral response, and motor or cognitive impairment compromises that reliability. Auditory brainstem response gave us stable threshold estimates across all frequencies. The result confirmed moderate sensorineural loss that we'd been underestimating by 20 to 30 dB because of his inconsistent responding. Therapy goals adjusted accordingly, and we incorporated visual hearing aids into our sessions rather than assuming he could hear everything he should have been hearing.

Bottom Line For Daily Practice

Learn to read an audiogram. Know what the symbols mean, what the patterns indicate, and when something doesn't add up. Keep current hearing evaluations on file for every client and request updated ones annually or whenever clinical status changes. Refer promptly for unilateral findings, asymmetry, sudden loss, or any discrepancy between behavior and test results. Don't let an old audiogram sit in a chart and determine your treatment assumptions for years. Collaborate with the audiologist on your caseload. Ask for the full report including tympanometry, word recognition scores, and recommendations. The intersection of audiology and speech-language pathology is where a lot of stalled progress gets unblocked, and it starts with knowing what you're looking at on that graph.