Conductive Hearing Loss Audiogram: How to Read and Interpret Hearing Test Results
An audiogram for conductive hearing loss reveals that the outer or middle ear’s sound transmission is damaged, but the inner ear is functioning normally. It is characterized by impaired air conduction thresholds in conjunction with normal bone conduction thresholds (0–20 dB), resulting in a noticeable “air-bone gap” of more than 15 dB.
Author: Dr Sagar Rajkuwar, ENT Specialist, Nashik, Maharashtra, India
🌐 www.entspecialistinnashik.com
The Audiogram’s Salient Characteristics
- Bone Conduction (BC): The bone conduction thresholds (typically indicated by (langle ) or (rangle )) will be within the normal hearing range (usually 0 – 20 dB). This shows that the cochlea (inner ear) is in good working order.
- AC (air conduction): The air conduction thresholds (represented by O for the right ear and X for the left ear) will be lower than the normal range (e.g., more than 25 dB), indicating some degree of hearing loss.
- This is the hallmark of conductive hearing loss: the Air-Bone Gap. It signifies the difference in decibels between the bone conduction threshold and the air conduction threshold for any particular
- frequency. A air-bone gap of more than 15 dB suggests that sound isn’t getting to the inner ear as it should.
Why is this taking place?
Conductive hearing loss results when the outer or middle ear’s ability to transmit sound waves to the inner ear is obstructed in some way.
Typical causes are:
- Overaccumulation of earwax (cerumen impaction), a foreign item, or swimmer’s ear (otitis externa).
- Middle Ear: A ruptured eardrum, fluid in the middle ear (otitis media), or stiffening of the middle ear bones (otosclerosis).
Steps to take next
It is strongly recommended to see an ENT (ear, nose, and throat) professional (otolaryngologist) if your audiogram reveals conductive hearing loss. Contrary to sensorineural hearing loss, conductive loss can frequently be treated.
An ENT will do a physical examination of the ear and may recommend: to determine the cause of your hearing loss and the most effective course of treatment.
- Medical Treatment: Antbiotics/medications for infections or fluid, or earwax removal.
- Surgical Choices: Operations such as mending middle-ear bone problems or inserting ear tubes.
- Amplification, using bone-anchored hearing devices or traditional hearing aids.
You may utilize materials like the ENT Health Specialist Finder or read more thorough interpretations on Geeky Medics to better understand your unique results or locate a local expert.
Table of Contents
- Introduction
- What is an audiogram?
- How Is Audiometry Done?
- Average of Pure Tones (PTA)
- Bone Conduction vs Air Conduction
- What is masking?
- Audiometric speech
- When Is an Audiogram Advised?
- Types of Hearing Loss on an Audiogram
- Audiogram Patterns in General
- Factors Affecting Accuracy of Audiograms
- Significance of an Audiogram in Medicine
- Conductive Hearing Loss: Frequently Asked Questions Audiogram
- Summary
Understanding and Interpreting Audiograms
Introduction
The official hearing test that evaluates a person’s ability to hear sounds at various frequencies and volumes is called an audiogram. This helps healthcare professionals detect diseases like sensorineural hearing loss, mixed hearing loss, and conductive hearing loss by identifying the kind, amount, and pattern of hearing loss.
One of the most important diagnostic instruments in audiology and otolaryngology (ENT) is audiometry. An audiogram determines whether hearing loss is due to the outer, middle, or inner ear, or to the auditory nerve, by evaluating air conduction and bone conduction hearing thresholds.
Certain audiogram patterns can point to conditions like age-related hearing loss (presbycusis), noise-induced hearing loss, Ménière’s disease, otosclerosis, vestibular schwannoma (acoustic neuroma), and hearing loss brought on by ototoxic medications, in addition to assessing hearing capacity.
What is an audiogram?
A graph that shows the softest sounds a person can hear over various sound frequencies is called an audiogram.
The hearing test:
- Through headphones, air conduction is utilized to play pure tones.
- Extra sounds can be sent via a bone vibrator positioned behind the ear (bone conduction).
- A sound is indicated by the patient.
- For interpretation, the findings are plotted on an audiogram.
This test assists in identifying:
- Hearing sensitivity
- Hearing impairment type
- How bad is the hearing loss?
- Hearing loss pattern
- The need for additional testing or treatment
How Is Audiometry Done?
To remove background noise, audiometry is typically done in a sound-treated booth.
Testing for air conduction
The whole hearing channel is assessed by air conduction:
- External ear
- Canal of the ear
- Eardrum
- Middle ear
- Cochlea (inner ear)
- Nerve responsible for hearing
- Brain
The patient wears headphones as sounds of varying frequencies and intensities are played.
Testing Using Bone Conduction
The outer and middle ears are circumvented during bone conduction testing.
The cochlea is immediately stimulated by a little vibrating device placed on the mastoid bone behind the ear.
This aids in identifying the cause of hearing loss as one of the following:
- Conductive hearing loss (disorder of the outer or middle ear)
- Auditory nerve or inner ear injury (sensorineural hearing loss)
Understanding the Audiogram
An audiogram has two main axes:
Horizontal Axis (X-axis)
Indicates the frequency (pitch) in Hertz (Hz).
The following frequencies are often evaluated:
- 250 hertz
- 500 hertz
- 1000 Hz
- 2 kHz
- 3000 hertz
- 4000 Hz
- 6000 Hertz
- 8 kHz
The majority of audible speech sounds occur between 500 Hz and 4000 Hz.
Y-axis, or vertical axis
Demonstrates the level of hearing measured in decibels (dB HL).
Normal hearing threshold is 0 dB HL.
Larger figures signify that louder noises are necessary before they can be heard.
In general:
- Normal hearing ranges from 0 to 25 dB HL.
- 26–40 dB Mild hearing loss according to HL.
- 41 to 55 dB HL: Moderate hearing loss
- 70-56 dB HL: Hearing loss of moderate severity
- 71-90 decibels HL: Serious loss of hearing
- More than 90 dB Profound hearing loss (HL)
Average of Pure Tones (PTA)
Hearing thresholds are used to compute the Pure Tone Average (PTA) at:
- 500 Hz
- 1000 Hz
- 2 kilohertz
PTA is frequently employed to evaluate the degree of hearing loss and to determine a person’s eligibility for a hearing aid. It provides a general assessment of a person’s hearing ability for speech comprehension.
Bone Conduction vs Air Conduction
Audiograms contrast two auditory pathways:
Conduction of Air
Evaluates hearing throughout the auditory system.
Conduction through Bone
Skips the outer and middle ear and activates the inner ear right away.
The sort of hearing loss may be determined by comparing these results.
What is masking?
The superior ear may identify sounds delivered to the poorer ear if one ear hears much better than the other.
Audiologists use masking, which involves introducing noise into the ear with better hearing while evaluating the other ear, in order to avoid getting results that are incorrect.
Particularly in individuals with asymmetrical hearing loss, masking enhances the accuracy of audiogram interpretation.
Audiometric speech
Pure-tone audiometry is supplemented by speech testing.
It analyzes:
- Speech Threshold (SDT)
- SRT (Speech Reception Threshold)
- WRS stands for Word Recognition Score.
How effectively a patient comprehends spoken words is assessed via these examinations, which also aid in evaluating communication skills.
Retrocochlear or auditory nerve problems might be indicated by relatively decent hearing thresholds combined with poor speech recognition.
When Is an Audiogram Advised?
An audiogram may be recommended by your doctor if you:
- Loss of hearing
- Tinnitus (ringing in the ears)
- Dizziness or lightheadedness
- Fullness of the ears
- Exposure to noise
- Damage to the skull
- Exposure to ototoxic drugs
- Sudden loss of hearing
- Deafness in the family’s past
For the following people, routine hearing screening is also advised:
- Senior people
- Children’s activities
- Workers in industry
- Members of the armed forces
- musicians
- Pilots
Types of Hearing Loss on an Audiogram
SNHL (Sensorineural Hearing Loss)
Damage to the cochlea, auditory nerve, or central auditory pathways causes sensorineural hearing loss.
Common causes include:
- Presbycusis, or aging
- Exposure to noise
- Ménière disease
- Medications that are ototoxic
- Infections with viruses
- Schwannoma of the vestibule
Audiogram results:
- The thresholds for bone conduction and air conduction drop simultaneously.
- There is no noticeable air-bone difference.
Hearing loss that is conductive in nature.
When sound cannot pass through the outer or middle ear efficiently, conductive hearing loss results.
Among the frequent causes are:
- Earwax obstruction
- Otitis media
- Tympanic membrane perforation
- Otosclerosis
- Fluid in the middle ear
Audiogram results:
- Regular bone conduction
- less air conduction
- 15 dB or more air-bone gap
A mixed hearing loss
Mixed hearing loss is characterized by both conductive and sensorineural components.
Audiogram results are as follows:
- Higher bone conduction threshold values
- High air conduction thresholds
- A large air-bone gap
Audiogram Patterns in General
Presbycusis
- Two-sided
- symmetrical
- Progressive hearing loss in the high frequency range
- Audiogram that slopes downward
Loss of Hearing Due to Noise
usually exhibits a noise notch at 4,000 Hz.
Common among:
- Manufacturing staff
- Music performers
- Military personnel
- Building workers
Meniere’s Disease
Common causes:
- One-sided low-frequency hearing loss
- Upsloping audiogram
- Hearing levels that are inconsistent
Vestibular Schwannoma
May yield:
- High-frequency hearing loss on one side
- Speech comprehension that is inadequate
- Asymmetrical audiogram
MRI is typically advised for confirmation.
Hearing Loss Due to Ototoxicity
Usually starts with high frequencies.
Related drugs are:
- Antibiotics in the Aminoglycoside Class
- Cisplatin
- Diuretics that are loop-like
- Salicylates in high doses
Otosclerosis
Can yield:
- Mixed or conductive hearing loss
- Bone-air gap
- At 2,000 Hz, a distinctive Carhart notch may be seen.
Hearing Loss at Birth
Some inherited hearing disorders show a “cookie-bite” audiogram with more severe hearing loss in the mid frequencies.
Factors Affecting Accuracy of Audiograms
There are a number of things that might affect audiogram results, including:
- Poorly placed headphones
- Inadequate coverage
- Noise in the background
- Patient weariness
- Lack of Collaboration
- Hearing loss that is functional (non-organic)
- Errors in equipment calibration
For trustworthy findings, a competent audiologist must conduct precise testing.
Significance of an Audiogram in Medicine
With the aid of an audiogram, doctors may:
- Diagnose auditory impairments.
- Find out how bad and what kind of hearing loss it is.
- Observe hearing modifications throughout time
- Give me some advice on hearing aids.
- Cochlear implants are considered.
- Find situations that need MRI or additional testing
- Inform rehabilitation and treatment
Because hearing loss may have a major impact on communication, education, employment, and quality of life, early diagnosis using audiometry is essential for enhancing long-term results.
Conductive Hearing Loss: Frequently Asked Questions Audiogram
1. What is an audiogram with conductive hearing loss?
The audiogram for conductive hearing loss is a graph of a hearing test that indicates reduced air conduction hearing with comparatively normal bone conduction. The inner ear is not the issue, according to this pattern, but rather the middle or outer ear.
2. What role does an audiogram play in identifying conductive hearing loss?
The air and bone conduction hearing thresholds are compared in an audiogram. A conductive hearing loss is often caused by defective sound transfer through the outer or middle ear, which is indicated by an air-bone gap of more than 10–15 dB.
3. What are the frequent causes of conductive hearing loss?
The following are typical causes:
- Blocked earwax (cerumen)
- Infection of the middle ear (otitis media)
- fluid behind the eardrum.
- Eardrum (tympanic membrane) perforation
- Otosclerosis
- The ear contains a foreign substance.
- Ear abnormalities present from birth
4. Is it possible to treat conductive hearing loss?
Yeah. In many cases, conductive hearing loss may be cured. Treatment may involve earwax removal, medications, antibiotics, hearing aids, or operations like stapedectomy or tympanoplasty, depending on the cause.
5. What is an audiogram’s air-bone gap?
The difference between air conduction and bone conduction hearing thresholds is known as an air-bone gap. It’s the defining symptom of conductive hearing loss and distinguishes it from sensorineural hearing loss.
6. Is hearing loss that is conductive irreversible?
Not always. Many situations are short-lived and improve with the treatment of the core cause. However, surgery or long-term hearing rehabilitation may be necessary for some diseases, such as congenital abnormalities or severe otosclerosis.
7. On an audiogram, how do conductive and sensorineural hearing loss differ?
Bone conduction is normal in conductive hearing loss, but air conduction is decreased, resulting in an air-bone gap. Both bone and air conduction fall simultaneously with no appreciable air-bone gap in sensorineural hearing loss.
When ought I get an audiogram?
If you have any of the following symptoms—hearing loss, tinnitus, ear fullness, recurring ear infections, dizziness, ear discharge, or trouble understanding speech, particularly in loud settings—you should have an audiogram.
9. Is it possible for children to have conductive hearing loss?
Yes, I do. Due to ear infections, enlarged adenoids, middle ear fluid, or congenital ear abnormalities, conductive hearing loss is frequent in youngsters. Speech and language delays can be avoided by early diagnosis.
10. Who interprets an audiogram?
A skilled audiologist or ENT expert should analyze audiograms, combining the results of the hearing test with your symptoms, medical history, and physical examination to identify the underlying cause.
Summary
An audiogram for conductive hearing loss aids in the detection of hearing problems brought on by disorders of the middle or outside ear. An air-bone difference, with air conduction thresholds being worse than bone conduction thresholds, is the telltale sign. Some of the causes of otosclerosis include earwax buildup, middle ear fluid, tympanic membrane perforation, and otosclerosis. Conductive hearing loss, unlike sensorineural hearing loss, may frequently be reversed with proper medical or surgical care.
Accurate diagnosis, timely treatment, and enhanced hearing results are ensured through early audiometric evaluation performed by an audiologist or ENT specialist.
Medical Disclaimer
Medical Disclaimer: This article is intended for educational and informational purposes only and should not be considered medical advice, diagnosis, or treatment. Audiogram results and hearing loss patterns should always be interpreted by a qualified audiologist or ENT specialist in conjunction with your symptoms, medical history, and clinical examination. If you experience sudden hearing loss, ear pain, persistent tinnitus, dizziness, or balance problems, seek immediate medical attention. Never delay or ignore professional medical care based on information provided in this article.
References
- American Speech-Language-Hearing Association (ASHA). Audiologic Assessment Guidelines.
- National Institute on Deafness and Other Communication Disorders (NIDCD). Hearing Tests.
- World Health Organization (WHO). World Report on Hearing.
- American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS). Clinical Practice Guidelines.
- StatPearls. Audiogram Interpretation. StatPearls Publishing.
- StatPearls. Sensorineural Hearing Loss. StatPearls Publishing.
- National Institute for Occupational Safety and Health (NIOSH). Occupational Noise Exposure Guidelines.
- National Institute for Health and Care Excellence (NICE). Hearing Loss in Adults: Assessment and Management.
