Unit 3: Identification of Deafness and Assessment of Hearing

Formal and informal assessment of hearing

The assessment of hearing aims to determine the degree (how much loss), the type (where the damage is), and the configuration (which frequencies are affected) of a hearing impairment.

Assessments are broadly divided into two categories:

• Informal Assessments: Non-standardized, behavioral checks often performed in natural environments (classrooms, homes) by parents or educators. They are used for screening and monitoring.
• Formal Assessments: Standardized, clinical tests performed in soundproof rooms using calibrated equipment by certified audiologists. They are used for clinical diagnosis.

Informal Assessment of Hearing

Informal assessments do not give you an audiogram or a specific decibel (dB) threshold. Instead, they tell you if a child is responding appropriately to environmental sounds and speech.

A. Behavioral Observation (The Educator’s Toolkit) Educators should constantly monitor for these “red flags” in the classroom:

1. Frequent Repetition: The child constantly says “What?” or “Huh?”
2. Visual Reliance: The child stares intensely at the teacher’s lips and struggles to understand instructions if the teacher faces the blackboard.
3. Volume Issues: The child speaks abnormally loudly or plays videos/music at maximum volume.
4. Inattention/Fatigue: The child appears to “daydream” or becomes exhausted by mid-day (due to listening fatigue).
5. Directional Confusion: The child cannot locate who is speaking in a group setting.

B. Environmental Sound Tests (For Infants/Toddlers)

• Distraction Test: Creating a sound (crinkling paper, shaking a rattle, ringing a bell) out of the child’s visual field to see if they turn their head to locate it.
• Name Calling: Calling the child’s name from behind at varying volumes (normal conversational voice vs. whisper).

C. The Ling Six Sound Test (Crucial for Daily Monitoring) This is the most important informal test for special educators. It is used daily to check if a child’s hearing aids or cochlear implants are working across the entire speech spectrum.

• The Concept: The test uses six specific phonemes—[m], [ah], [oo], [ee], [sh], [s]—that represent the lowest to the highest frequencies of human speech.
• The Process: The educator covers their mouth (so the child cannot lip-read) and says the sounds at a normal conversational volume. The child must repeat the sound or drop a block in a bucket when they hear it.
• The Result: If the child can hear all six sounds, they have access to the entire acoustic spectrum of speech for that day. If they suddenly miss [s] and [sh], the battery in their hearing aid might be dying, or their inner ear fluid might have changed.

Formal Assessment: Subjective (Behavioral) Tests

These clinical tests require the patient’s active participation and behavioral response (e.g., raising a hand, pressing a button).

A. Pure Tone Audiometry (PTA)

• The Gold Standard: This is the primary test used for adults and older children (usually 5+ years).
• Mechanism: The patient sits in a soundproof booth wearing headphones. The audiologist plays “pure tones” at specific frequencies (pitches) and varying volumes (decibels). The patient raises their hand when they hear a beep.
• Air Conduction vs. Bone Conduction:
  • Air Conduction: Sounds are played through headphones, testing the entire ear pathway (Outer $\rightarrow$ Middle $\rightarrow$ Inner).
  • Bone Conduction: A vibrating headband is placed on the mastoid bone behind the ear. This physically vibrates the skull, sending sound directly to the inner ear (Cochlea), bypassing the outer and middle ear entirely.
  • Diagnostic Value: By comparing Air and Bone conduction scores, the audiologist can definitively tell if the loss is Conductive, Sensorineural, or Mixed.

B. Speech Audiometry

• Tests how well the patient hears and understands actual human speech, not just beeps.
• Speech Reception Threshold (SRT): The softest volume at which a patient can correctly repeat 50% of simple, two-syllable words (e.g., “hotdog,” “baseball”).
• Speech Discrimination Score (SDS): Played at a comfortably loud volume to test clarity. The patient repeats words like “cat” or “cap.” If they get a low score even when the volume is loud, it indicates severe nerve distortion (Sensorineural loss).

C. Pediatric Behavioral Tests

Because babies cannot raise their hands, audiologists modify PTA for children:

• Behavioral Observation Audiometry (BOA) (0-6 months): The audiologist plays sounds and watches for unconditioned reflexes (startling, eye-widening, cessation of sucking).
• Visual Reinforcement Audiometry (VRA) (6 months – 2 years): The child is conditioned to turn their head toward a sound. When they do, they are rewarded with a fun visual reinforcement (like an animated toy lighting up in a dark box).
• Play Audiometry (2 – 5 years): The child is taught to perform a play task (e.g., dropping a peg in a board or a block in a bucket) every time they hear a beep.

Formal Assessment: Objective Tests

These clinical tests require no active response from the patient. The patient can be asleep or unconscious. These are critical for newborn hearing screening, individuals with severe intellectual disabilities, or malingerers (people faking a hearing loss).

A. Otoacoustic Emissions (OAE)

• Mechanism: A tiny microphone is placed in the ear canal. It plays a series of clicking sounds.
• The Science: When healthy outer hair cells in the cochlea receive sound, they physically vibrate and generate their own faint “echo” back out into the ear canal. The microphone measures this echo.
• Result: If an echo is present (Pass), the outer and middle ear are generally healthy. If there is no echo (Refer), there is likely a blockage or cochlear damage. (This is the primary tool for Universal Newborn Hearing Screening).

B. Brainstem Evoked Response Audiometry (BERA / ABR)

• Mechanism: Electrodes are pasted to the baby’s scalp and earlobes. Clicking sounds are played through earphones.
• The Science: The electrodes measure the electrical activity of the Auditory Nerve and the Brainstem as the sound travels up to the brain.
• Result: It tells the audiologist exactly how fast the electrical signal is moving and at what decibel level the brain stops registering the sound. It is highly accurate for diagnosing severe sensorineural loss in infants.

C. Tympanometry (Impedance Audiometry)

• Mechanism: A probe is placed in the ear canal that changes air pressure and plays a tone.
• The Science: It measures the mobility (movement) of the Tympanic Membrane (eardrum) and the middle ear bones.
• Result: It does not test hearing. It tests physical mechanics. It can instantly diagnose if there is a hole in the eardrum, fluid behind the eardrum (Otitis Media), or stiff ossicles.

Here are comprehensive notes on the Formal and Informal Assessment of Hearing.

For a special educator or speech-language pathologist, understanding both pathways is vital. While you will not clinically diagnose hearing loss (that is the audiologist’s job using formal tests), you are the front line for identifying red flags and monitoring daily hearing aid function using informal tests.

Introduction to Hearing Assessment

The assessment of hearing aims to determine the degree (how much loss), the type (where the damage is), and the configuration (which frequencies are affected) of a hearing impairment.

Assessments are broadly divided into two categories:

• Informal Assessments: Non-standardized, behavioral checks often performed in natural environments (classrooms, homes) by parents or educators. They are used for screening and monitoring.
• Formal Assessments: Standardized, clinical tests performed in soundproof rooms using calibrated equipment by certified audiologists. They are used for clinical diagnosis.

Informal Assessment of Hearing

Informal assessments do not give you an audiogram or a specific decibel (dB) threshold. Instead, they tell you if a child is responding appropriately to environmental sounds and speech.

A. Behavioral Observation (The Educator’s Toolkit)

Educators should constantly monitor for these “red flags” in the classroom:

• Frequent Repetition: The child constantly says “What?” or “Huh?”
• Visual Reliance: The child stares intensely at the teacher’s lips and struggles to understand instructions if the teacher faces the blackboard.
• Volume Issues: The child speaks abnormally loudly or plays videos/music at maximum volume.
• Inattention/Fatigue: The child appears to “daydream” or becomes exhausted by mid-day (due to listening fatigue).
• Directional Confusion: The child cannot locate who is speaking in a group setting.

B. Environmental Sound Tests (For Infants/Toddlers)

• Distraction Test: Creating a sound (crinkling paper, shaking a rattle, ringing a bell) out of the child’s visual field to see if they turn their head to locate it.
• Name Calling: Calling the child’s name from behind at varying volumes (normal conversational voice vs. whisper).

C. The Ling Six Sound Test (Crucial for Daily Monitoring)

This is the most important informal test for special educators. It is used daily to check if a child’s hearing aids or cochlear implants are working across the entire speech spectrum.

• The Concept: The test uses six specific phonemes—[m], [ah], [oo], [ee], [sh], [s]—that represent the lowest to the highest frequencies of human speech.
• The Process: The educator covers their mouth (so the child cannot lip-read) and says the sounds at a normal conversational volume. The child must repeat the sound or drop a block in a bucket when they hear it.
• The Result: If the child can hear all six sounds, they have access to the entire acoustic spectrum of speech for that day. If they suddenly miss [s] and [sh], the battery in their hearing aid might be dying, or their inner ear fluid might have changed.

Formal Assessment: Subjective (Behavioral) Tests

These clinical tests require the patient’s active participation and behavioral response (e.g., raising a hand, pressing a button).

A. Pure Tone Audiometry (PTA)

• The Gold Standard: This is the primary test used for adults and older children (usually 5+ years).
• Mechanism: The patient sits in a soundproof booth wearing headphones. The audiologist plays “pure tones” at specific frequencies (pitches) and varying volumes (decibels). The patient raises their hand when they hear a beep.
• Air Conduction vs. Bone Conduction:
  • Air Conduction: Sounds are played through headphones, testing the entire ear pathway (Outer $\rightarrow$ Middle $\rightarrow$ Inner).
  • Bone Conduction: A vibrating headband is placed on the mastoid bone behind the ear. This physically vibrates the skull, sending sound directly to the inner ear (Cochlea), bypassing the outer and middle ear entirely.
  • Diagnostic Value: By comparing Air and Bone conduction scores, the audiologist can definitively tell if the loss is Conductive, Sensorineural, or Mixed.

B. Speech Audiometry

• Tests how well the patient hears and understands actual human speech, not just beeps.
• Speech Reception Threshold (SRT): The softest volume at which a patient can correctly repeat 50% of simple, two-syllable words (e.g., “hotdog,” “baseball”).
• Speech Discrimination Score (SDS): Played at a comfortably loud volume to test clarity. The patient repeats words like “cat” or “cap.” If they get a low score even when the volume is loud, it indicates severe nerve distortion (Sensorineural loss).

C. Pediatric Behavioral Tests

Because babies cannot raise their hands, audiologists modify PTA for children:

• Behavioral Observation Audiometry (BOA) (0-6 months): The audiologist plays sounds and watches for unconditioned reflexes (startling, eye-widening, cessation of sucking).
• Visual Reinforcement Audiometry (VRA) (6 months – 2 years): The child is conditioned to turn their head toward a sound. When they do, they are rewarded with a fun visual reinforcement (like an animated toy lighting up in a dark box).
• Play Audiometry (2 – 5 years): The child is taught to perform a play task (e.g., dropping a peg in a board or a block in a bucket) every time they hear a beep.

4. Formal Assessment: Objective Tests

These clinical tests require no active response from the patient. The patient can be asleep or unconscious. These are critical for newborn hearing screening, individuals with severe intellectual disabilities, or malingerers (people faking a hearing loss).

A. Otoacoustic Emissions (OAE)

• Mechanism: A tiny microphone is placed in the ear canal. It plays a series of clicking sounds.
• The Science: When healthy outer hair cells in the cochlea receive sound, they physically vibrate and generate their own faint “echo” back out into the ear canal. The microphone measures this echo.
• Result: If an echo is present (Pass), the outer and middle ear are generally healthy. If there is no echo (Refer), there is likely a blockage or cochlear damage. (This is the primary tool for Universal Newborn Hearing Screening).

B. Brainstem Evoked Response Audiometry (BERA / ABR)

• Mechanism: Electrodes are pasted to the baby’s scalp and earlobes. Clicking sounds are played through earphones.
• The Science: The electrodes measure the electrical activity of the Auditory Nerve and the Brainstem as the sound travels up to the brain.
• Result: It tells the audiologist exactly how fast the electrical signal is moving and at what decibel level the brain stops registering the sound. It is highly accurate for diagnosing severe sensorineural loss in infants.

C. Tympanometry (Impedance Audiometry)

• Mechanism: A probe is placed in the ear canal that changes air pressure and plays a tone.
• The Science: It measures the mobility (movement) of the Tympanic Membrane (eardrum) and the middle ear bones.
• Result: It does not test hearing. It tests physical mechanics. It can instantly diagnose if there is a hole in the eardrum, fluid behind the eardrum (Otitis Media), or stiff ossicles.

Summary Comparison Table

Feature	Informal Assessment	Formal Assessment
Purpose	Screening and daily monitoring.	Clinical diagnosis, prescribing hearing aids.
Environment	Natural (Classroom, Home).	Soundproof clinical booth.
Tools	Noisemakers, voice, Ling Six sounds.	Calibrated Audiometers, OAE, BERA equipment.
Administrator	Teacher, Parent, Special Educator.	Certified Audiologist.
Result	“Pass/Refer” or behavioral notes.	Specific Audiogram with exact dB and Hz loss.

Interactive Exploration: The Ling Six Sound Test & The Audiogram

To understand how educators bridge the gap between informal daily checks and formal audiological science, you must understand how the Ling Six Sounds map onto a formal audiogram.

Use the simulator below to select different Ling sounds. Notice how they correspond to specific physical frequencies on the audiogram, and observe why a child with a high-frequency hearing loss will fail specific parts of your informal classroom assessment.

Conditioning for auditory assessment

The Core Principle: Operant Conditioning

The entire process is based on B.F. Skinner’s principle of Operant Conditioning. A child’s behavior is shaped and maintained by its consequences.

In audiology, this requires a strict three-step loop:

1. Stimulus: The audiologist plays a sound (e.g., a beep or a voice).
2. Response: The child performs a specific motor action (e.g., turning their head or dropping a block).
3. Reinforcement: The child immediately receives a positive reward (e.g., a flashing toy or praise).

Crucial Rule: The reinforcement must be highly motivating, and it must occur only when the child responds correctly to the sound. If the child gets the reward for doing nothing, the conditioning breaks down.

Types of Conditioned Assessments by Age

Audiologists use different conditioning techniques based on the child’s neuro-motor development.

A. Visual Reinforcement Audiometry (VRA)

• Target Age: 6 months to 2.5 years.
• The Setup: The child sits on a parent’s lap in a soundproof booth. Speakers are placed on the left and right sides. Next to each speaker is a dark plexiglass box containing a mechanical toy (like a drumming bear or a puppy).
• The Conditioned Response: A head turn.
• The Reinforcement: When the child turns their head toward the sound, the dark box lights up, and the mechanical toy dances.
• Why it works: At 6 months, babies develop the neck strength to reliably turn their heads, and they are highly visually curious. The dancing toy is a massive visual reward.

B. Conditioned Play Audiometry (CPA)

• Target Age: 2.5 years to 5 years.
• The Setup: The child sits at a tiny table, usually wearing headphones. The audiologist introduces a simple, repetitive game (e.g., putting a peg in a board, dropping a block into a bucket, or stacking rings).
• The Conditioned Response: A play action. The child must hold the block up to their ear, wait, and drop it into the bucket only when they hear the beep.
• The Reinforcement: Enthusiastic social praise from the audiologist (“Yay! Good job!”), a high-five, or the satisfaction of completing the puzzle.
• Why it works: Toddlers have the fine motor skills to hold and drop objects. They are transitioning from visual curiosity to play-based task completion and seek adult approval.

3. The Process of Conditioning (Step-by-Step)

Whether using VRA or CPA, the audiologist follows a strict sequence to teach the child the rules.

Step 1: The Training (Acquisition) Phase

• The audiologist plays a sound that is loud enough for the child to definitely hear.
• For CPA: The audiologist physically takes the child’s hand, holds the block to the ear, plays the loud sound, and physically guides the child’s hand to drop the block. They immediately cheer.
• For VRA: The sound and the visual toy are triggered at the exact same time to show the baby, “Look, sound means toy!”
• This pairing is repeated 2 to 4 times until the child makes the connection.

Step 2: The Testing Phase

• The audiologist plays a softer sound and waits.
• They do not physically prompt the child. They wait for the child to drop the block or turn their head independently.
• As soon as the child responds correctly, the reinforcement is given. The audiologist then lowers the volume further to find the threshold.

Step 3: Managing Extinction (Fatigue)

• Children have short attention spans. Eventually, dropping a block or looking at the same toy becomes boring. When the reward loses its value, the child stops responding (this is called extinction).
• To prevent this, the audiologist must work very fast, switch out the toys frequently (e.g., move from dropping blocks to putting puzzle pieces together), or change the visual reinforcement to keep the child motivated.

4. Challenges in Conditioning

• False Positives: The child drops the block without hearing a sound, just because they want the reward. The audiologist must withhold the reward and re-train the child to “Wait.”
• Developmental Delays: A 4-year-old with severe cognitive delays or Autism Spectrum Disorder may not possess the attention span for CPA. In these cases, the audiologist may have to regress and use VRA, regardless of the child’s chronological age.
• Severe Hearing Loss: If a child is profoundly deaf, they cannot hear the training tones. The audiologist may have to use a vibrotactile stimulus (a vibrating bone-conduction headband) to teach the game before attempting to find acoustic thresholds.

Pedagogical Implication (For the Special Educator)

Clinical audiology time is incredibly expensive and limited. Often, a child is too scared of the hospital environment to learn a new game in 15 minutes.

Pre-Conditioning in the Classroom: Special educators play a massive role by “pre-conditioning” the child at school. Before an audiology appointment, the educator should spend a week playing the “Listening Game” with a drum or a whistle, teaching the child to wait, listen, and drop a block. When the child arrives at the clinic, they already know the rules, leading to a much faster and more accurate hearing test.

Interactive Exploration: Conditioned Play Audiometry (CPA) Simulator

To truly understand how operant conditioning works in a clinical setting, you must balance prompting, waiting, and reinforcing before the child loses interest.

Use the simulator below to play the role of the Audiologist. Teach the child the rules of the game during the Training Phase, then try to test them.

Audiometery for children

Core Concepts in Pediatric Audiometry

A. Developmental Age vs. Chronological Age

• Audiologists select a hearing test based on a child’s developmental age (their neuro-motor and cognitive milestones), not just their chronological age.
• Example: A 4-year-old with a severe intellectual disability may not have the cognitive capacity to play a structured hearing game. The audiologist will test them using methods designed for a 9-month-old.

B. The “Cross-Check” Principle

• Formulated by Jerger and Hayes (1976), this is the golden rule of pediatric audiology: No single test result should be accepted without independent verification from another test.
• Because children can be uncooperative, tired, or frightened, behavioral test results are often unreliable. An audiologist must “cross-check” a behavioral test (like seeing the child turn their head) with an objective physiological test (like an OAE or ABR) before making a final diagnosis or fitting hearing aids.

Objective Tests (No Active Response Required)

These tests measure the physiological response of the ear and brain. The child can be asleep, sedated, or quietly resting. They form the foundation of the Cross-Check principle.

• Otoacoustic Emissions (OAE):
  • How it works: A small probe plays a sound into the ear. If the outer hair cells of the cochlea are healthy, they produce a faint “echo” back into the ear canal, which is recorded by the probe.
  • Use in Children: This is the primary tool for Universal Newborn Hearing Screening (UNHS). It is fast (takes minutes) and painless. A “Refer” (fail) indicates possible cochlear damage or fluid in the middle ear.
• Brainstem Evoked Response Audiometry (BERA / ABR):
  • How it works: Electrodes are placed on the baby’s head. Sounds are played through earphones. The electrodes measure the electrical activity of the auditory nerve and brainstem to see if the sound successfully traveled from the ear to the brain.
  • Use in Children: This is the definitive diagnostic test for infants under 6 months. It can estimate the exact decibel (dB) threshold of a baby’s hearing without them ever waking up.
• Tympanometry:
  • How it works: Measures how well the eardrum moves by changing air pressure in the ear canal.
  • Use in Children: Extremely critical for toddlers. Young children frequently get Otitis Media (fluid in the middle ear). Tympanometry instantly confirms if a child’s hearing loss is simply due to a temporary fluid buildup (Conductive) rather than permanent nerve damage.

Subjective (Behavioral) Tests by Age Group

These tests require the child to respond to sound. The audiologist uses the child’s natural reflexes or conditions them to play a game.

A. Behavioral Observation Audiometry (BOA)

• Target Age: 0 to 6 Months.
• The Method: The child sits on the parent’s lap in a soundproof booth. The audiologist plays sounds (speech, noise-makers, or warble tones) through speakers and carefully observes the baby’s unconditioned reflexes.
• Expected Responses: Eye-widening, cessation of sucking on a pacifier, startling (Moro reflex), or waking from light sleep.
• Limitations: Highly subjective. A baby will only startle to very loud sounds, so BOA cannot accurately diagnose mild or moderate hearing loss. It must be cross-checked with an ABR.

B. Visual Reinforcement Audiometry (VRA)

• Target Age: 6 Months to 2.5 Years.
• The Method (Operant Conditioning): The child is taught to turn their head toward a speaker when they hear a sound. When they do, they are immediately rewarded with a visual reinforcement (a dark box lights up to reveal a dancing, mechanical toy or a cartoon screen).
• Why it works: By 6 months, babies have the neck control to turn their heads and are highly motivated by visual stimuli.
• The Result: The audiologist can test different frequencies and lower the volume until the child stops turning their head, finding the minimum hearing threshold.

C. Conditioned Play Audiometry (CPA)

• Target Age: 2.5 Years to 5 Years.
• The Method (Play-Based Conditioning): The child is taught to perform a fun, repetitive motor task only when they hear a beep. For example, “Hold this block next to your ear. When you hear the birdie (the beep), drop the block into the bucket!”
• Why it works: Toddlers have outgrown the dancing toys of VRA but are highly motivated by play tasks and adult praise (“Good job!”).
• The Result: If the child is cooperative, CPA can yield a complete, highly accurate ear-specific audiogram, just like an adult test.

Pediatric Speech Audiometry

Testing how a child hears human speech is just as important as testing how they hear beeps. However, a 3-year-old cannot repeat complex words like an adult can.

• Speech Detection Threshold (SDT) / Speech Awareness Threshold (SAT):
  • Used for infants or children with severe language delays.
  • The audiologist just wants to know the softest volume at which the child notices speech is happening. The audiologist might say “Ba ba ba” or call the child’s name, looking for a VRA head-turn.
• Speech Reception Threshold (SRT) (Modified for Children):
  • Used to find the softest volume at which a child can understand a word.
  • Instead of asking the child to repeat the word, the audiologist uses a picture-pointing task. The audiologist puts cards on a table (e.g., Ice Cream, Hot Dog, Airplane) or asks the child to point to body parts (“Show me your nose”). The volume is lowered until the child can no longer point to the correct item.

Clinical Notes for Special Educators

1. Multiple Sessions are the Norm: A 2-year-old has an attention span of about 10-15 minutes. It is perfectly normal for a pediatric audiogram to take 2 or 3 separate clinic visits to complete before the child gets bored or throws a tantrum (fatigue/extinction).
2. The Educator’s Role in Testing: An educator can drastically reduce testing time by “pre-conditioning” a child in the classroom. If an educator spends a week playing the “Listen and Drop the Block” game with a drum before the child goes to the hospital, the child will already know the rules of CPA when they arrive, allowing the audiologist to get accurate thresholds immediately.

Interactive Exploration: The Pediatric Test Battery Selector

Because test selection depends entirely on the child’s physical, cognitive, and developmental state, audiologists must dynamically build a test battery for each unique patient. Use the simulator below to select a child’s age and developmental status to see how the clinical protocol changes.

Audiograms and its interpretation

An audiogram is a standardized graph that displays the results of a Pure Tone Audiometry (PTA) test. It plots the softest sounds a person can hear (their threshold) across different pitches.

Understanding the Axes:

• The X-Axis (Horizontal): Frequency (Pitch)
  • Measured in Hertz (Hz).
  • It reads from left to right, going from low pitch (like a bass drum at 250 Hz) to high pitch (like a bird chirping at 8000 Hz).
  • Note: The most critical frequencies for human speech are between 500 Hz and 4000 Hz.
• The Y-Axis (Vertical): Intensity (Loudness)
  • Measured in Decibels Hearing Level (dB HL).
  • It reads from top to bottom. The top of the graph (-10 dB to 0 dB) represents very soft sounds. The bottom of the graph (100 dB to 120 dB) represents extremely loud, painful sounds.
  • Crucial Rule: The further down the marks are on the graph, the worse the hearing loss.

The Standard Symbols

Audiologists use a universal code of symbols to differentiate the right ear from the left ear, and Air Conduction from Bone Conduction.

Right Ear (Traditionally recorded in Red)

• O = Air Conduction (Unmasked)
• < = Bone Conduction (Unmasked)
• [ = Bone Conduction (Masked)

Left Ear (Traditionally recorded in Blue)

• X = Air Conduction (Unmasked)
• > = Bone Conduction (Unmasked)
• ] = Bone Conduction (Masked)

Definitions:

• Air Conduction (AC): Tests the whole ear (Outer $\rightarrow$ Middle $\rightarrow$ Inner). Uses headphones.
• Bone Conduction (BC): Bypasses the outer and middle ear, testing only the Inner Ear (Cochlea). Uses a vibrating headband.

Step 1: Determining the Degree (Severity) of Hearing Loss

To find the degree, you look at where the Air Conduction (AC) symbols fall on the Y-axis. (Calculate the Pure Tone Average—the average dB at 500, 1000, and 2000 Hz).

• -10 to 25 dB HL: Normal Hearing
• 26 to 40 dB HL: Mild Hearing Loss
• 41 to 55 dB HL: Moderate Hearing Loss
• 56 to 70 dB HL: Moderately Severe Hearing Loss
• 71 to 90 dB HL: Severe Hearing Loss
• 91+ dB HL: Profound Hearing Loss

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4. Step 2: Determining the Type of Hearing Loss (The Golden Rules)

To determine the type of hearing loss, you must compare the Air Conduction (AC) scores to the Bone Conduction (BC) scores. The space between them is called the Air-Bone Gap (ABG).

• An ABG is considered clinically significant if it is greater than 10 dB.

Rule 1: Sensorineural Hearing Loss (SNHL)

• Pattern: Both AC and BC are abnormal (below 25 dB).
• The Gap: There is NO Air-Bone Gap. AC and BC are within 10 dB of each other.
• Interpretation: Because bone conduction is just as bad as air conduction, the problem is deep in the inner ear (cochlea) or nerve.

Rule 2: Conductive Hearing Loss (CHL)

• Pattern: BC is NORMAL (above 25 dB). AC is ABNORMAL (below 25 dB).
• The Gap: There IS a significant Air-Bone Gap (> 10 dB).
• Interpretation: The inner ear (tested by BC) is perfectly healthy. But sound cannot get through the outer/middle ear (tested by AC). There is a blockage (wax, fluid, or stiff bones).

Rule 3: Mixed Hearing Loss (MHL)

• Pattern: Both AC and BC are ABNORMAL (below 25 dB).
• The Gap: There IS a significant Air-Bone Gap (> 10 dB). AC is significantly worse than BC.
• Interpretation: The patient has inner ear damage (shown by the abnormal BC), but they also have a middle ear blockage making the hearing even worse (shown by the gap and worse AC).

Step 3: Determining the Configuration (Shape)

Configuration describes how the hearing loss is shaped across the frequencies.

• Flat: Thresholds are roughly the same across all frequencies.
• Sloping: Hearing is better in the low frequencies and drops down in the high frequencies (common in age-related loss and noise damage).
• Rising: Hearing is poor in low frequencies and gets better in high frequencies (common in Conductive loss or Meniere’s disease).
• Cookie Bite: Hearing is normal at the very low and very high ends, but drops in the middle (U-shape). Usually genetic.
• Noise Notch: Normal hearing that drops sharply exactly at 4000 Hz, then recovers at 8000 Hz. The classic sign of acoustic trauma/noise-induced hearing loss.

Interactive Audiogram Interpreter

To truly master audiogram interpretation, you must visualize how Air Conduction and Bone Conduction interact to form the “Air-Bone Gap.”

Use the simulator below to select different clinical profiles. Watch how the symbols shift on the graph and read the diagnostic logic panel to understand why the audiogram is interpreted that way.

Speech banana and its interpretations

The “Speech Banana” is a specific, banana-shaped region plotted on an audiogram that represents where all the phonemes (sounds) of conversational human speech occur in terms of frequency (pitch) and intensity (loudness).

• Why a banana shape? Human speech is not perfectly flat across all pitches. Most speech sounds cluster in the middle frequencies at moderate conversational volumes, tapering off at the extreme high/low frequencies and very soft/loud intensities. When you map these sounds on an audiogram and draw an outline around them, it forms the shape of a banana.

Mapping the Axes of the Speech Banana

To interpret the banana, you must understand the standard audiogram grid:

• The X-Axis (Frequency/Pitch): Runs horizontally from 250 Hz (low pitch, like a tuba) to 8000 Hz (high pitch, like a whistle).
• The Y-Axis (Intensity/Loudness): Runs vertically downwards. The top is 0 dB (very soft), and the bottom is 120 dB (painfully loud).
• The Location: The speech banana primarily spans from 250 Hz to 6000 Hz and hovers roughly between 20 dB and 60 dB HL (the volume of normal conversational speech).

The Anatomy of the Banana: Where Do Sounds Live?

Understanding where specific sounds live inside the banana allows an educator to predict exactly what a child will struggle with.

A. The Left Side (Low Frequencies: 250 Hz – 1000 Hz)

• The Sounds: Vowels (/a/, /o/, /u/), nasals (/m/, /n/, /ng/), and voiced consonants (/b/, /d/, /g/).
• The Function: These sounds carry the Power and rhythm of speech. They are generally louder (closer to the bottom of the banana).
• Interpretation: If a child has normal low-frequency hearing, they will hear the melody and volume of a voice. They will know that someone is talking.

B. The Right Side (High Frequencies: 2000 Hz – 8000 Hz)

• The Sounds: Voiceless fricatives and sibilants (/f/, /s/, /th/, /sh/, /k/).
• The Function: These sounds carry the Clarity and meaning of speech. They are generally much softer (closer to the top of the banana).
• Interpretation: Without these sounds, speech sounds completely muffled. The words “Math,” “Map,” and “Mat” all sound identical (just “Ma”) because the high-frequency ending consonant is lost.

Advanced Concept: Vowel Formants

At a diploma level, it is important to know that vowels are not just one single frequency. They have energy peaks called Formants.

• F1 (First Formant): Lives in the low frequencies. It tells the listener that a vowel is being spoken.
• F2 (Second Formant): Lives in the higher frequencies (1000 Hz – 3000 Hz). F2 provides the clarity. A child must be able to hear the higher F2 frequency to distinguish between the vowel /i/ (as in “beat”) and the vowel /u/ (as in “boot”).

Interpreting Hearing Loss Profiles via the Speech Banana

When an audiologist plots a patient’s hearing threshold line on the audiogram, any part of the Speech Banana that falls above the line (in the softer dB range) is inaudible to the patient.

• High-Frequency Sloping Loss (The “Ski Slope”):
  • Threshold: The line drops drastically on the right side of the graph.
  • Interpretation: The left side of the banana (vowels) is below the line (audible). The right side of the banana (/s/, /f/, /th/) is above the line (inaudible).
  • Result: The patient says, “I can hear people talking, but they mumble.” They will drop plural ‘s’ markers and struggle to hear women’s or children’s voices.
• Flat Moderate Loss:
  • Threshold: The line cuts straight across the middle of the banana horizontally (around 50 dB).
  • Interpretation: Only the very loudest vowels (the bottom tip of the banana) might be heard.
  • Result: Conversational speech is entirely missed without hearing aids.
• “Cookie Bite” Hearing Loss:
  • Threshold: Hearing is good at the far left and far right, but dips in the middle frequencies (1000 – 2000 Hz).
  • Interpretation: The patient misses the core acoustic energy of speech. They might hear environmental sounds perfectly but struggle to understand a teacher in a classroom.

Educational and Pedagogical Implications

Why do special educators use the Speech Banana?

1. Predicting Speech Errors: If you look at a child’s audiogram and see they cannot hear 4000 Hz, you can predict they will not naturally articulate the /s/ sound. You must address this in speech therapy.
2. Validating Hearing Aid Fittings: An audiologist programs a hearing aid to push the entire Speech Banana down into the child’s audible range. Educators use the “Ling Six Sound Test” daily to verify that the child can access the whole banana.
3. Justifying Accommodations: Showing a teacher a student’s audiogram overlaid with the Speech Banana is the most effective way to explain why the student needs preferential seating or an FM system, visually proving that they literally cannot hear the consonants of the lesson.

Interactive Exploration: Interpreting the Speech Banana

To master this concept, you must practice mapping phonetic errors to specific audiogram profiles. Use the simulator below to select different clinical hearing profiles. Observe how the threshold line cuts through the banana and read the interpretation panel to understand the real-world communication impact.