Unit 4: Evaluation of Hearing

Fill in the blanks:

1. The ________________________ is a graph that represents the results of a hearing test.
2. In the Rinne test, a ________________________ result indicates that the individual has conductive hearing loss.
3. The ________________________ tuning fork is the most commonly used frequency for clinical hearing tests.
4. On an audiogram, the color ________________________ is used to represent the right ear, while ________________________ represents the left ear.
5. The lowest intensity of sound a person can hear at least 50% of the time is called the ________________________.
6. ________________________ is a special procedure used to prevent the better ear from participating while testing the poorer ear.
7. ________________________ is a technique used for young children who cannot follow standard behavioral instructions.
8. The pure-tone average (PTA) is calculated by averaging air conduction thresholds at ________________________ Hz.
9. ________________________ is the process of checking whether the signals presented by the audiometer are accurate.
10. If hearing loss affects only one ear, it is referred to as ________________________ hearing loss.

Answers:

1. Audiogram
2. Rinne-negative
3. 512 Hz
4. Red, Blue
5. Threshold
6. Masking
7. Play audiometry
8. 500, 1000 and 2000 Hz
9. Calibration
10. Unilateral

Tick the correct option:

1. Which axis of an audiogram represents Intensity (loudness)?

a) Horizontal (X-axis)

b) Vertical (Y-axis)

c) Both

d) None

2. What is the symbol for Left Ear Air Conduction on an audiogram?

a) O

b) X

c) <

d) >

3. Which test is considered “objective” because it requires no intentional response from the patient?

a) Pure-tone audiometry

b) Speech audiometry

c) Auditory Brainstem Response (ABR)

d) Tuning fork test

4. In the Weber test, if the sound is heard louder in the ear with hearing loss, it suggests:

a) Conductive loss

b) Sensorineural loss

c) Normal hearing

d) APD

5. Which frequency range is typically tested during bone conduction?

a) 125–8000 Hz

b) 250–4000 Hz

c) 500–2000 Hz

d) 1000–8000 Hz

6. A “sloping” configuration on an audiogram indicates:

a) Low-frequency loss

b) High-frequency loss

c) Equal loss

d) No loss

7. Which degree of hearing loss corresponds to a PTA of 71 to 90 dB HL?

a) Moderate

b) Moderately Severe

c) Severe

d) Profound

8. What does “0 dB HL” represent on an audiogram?

a) Total silence

b) Softest sound a normal ear hears

c) Loud noise

d) Absence of sound

9. Which component of the audiometer is used to deliver sound directly to the skull?

a) Headphones

b) Insert earphones

c) Loudspeaker

d) Bone vibrator

10. Speech Identification Scores (SIS) are used to measure:

a) Speech loudness

b) Clarity/Understanding of words

c) Detection of sound

d) Bone conduction

Answers:

1. Vertical (Y-axis)
2. X
3. Auditory Brainstem Response (ABR)
4. Conductive loss
5. 250-4000 Hz
6. High-frequency loss
7. Severe
8. Softest sound a normal ear hears
9. Bone vibrator
10. Clarity/Understanding of words

True or false:

1. 0 dB HL means there is absolutely no sound present.
2. Bone conduction testing bypasses the external and middle ear.
3. A screening test provides the exact degree and type of hearing loss.
4. Sensorineural hearing loss shows an air-bone gap of less than 10 dB.
5. Hearing tests should be conducted in a noisy environment to simulate real life.
6. Play audiometry uses blocks or marbles to keep a child engaged.
7. A rising configuration means the person hears high frequencies better than low ones.
8. Tuning fork tests are more reliable than audiometric tests.
9. Asymmetrical hearing loss requires a special procedure called masking.
10. Speech audiometry helps predict how much a person will benefit from a hearing aid.

Answers:

1. False
2. True
3. False
4. True
5. False
6. True
7. True
8. False
9. True
10. True

Very short answer type questions:

1. What is an Audiogram?
2. What is the purpose of a case history?
3. What is the symbol for right ear bone conduction?
4. Define ‘Hearing Threshold’?
5. What is the difference between air conduction and bone conduction?
6. What is ‘Reverberation’?
7. Name the instrument used for subjective hearing evaluation.
8. What frequency is first tested in pure-tone audiometry?
9. What is a ‘Bilateral’ hearing loss?
10. What is ‘Calibration’?

Answers:

1. A graph used to plot a person’s hearing thresholds across different frequencies and intensities.
2. To collect background info on onset, symptoms, and medical history to guide the assessment.
3. The symbol is <.
4. The softest level at which a sound is heard 50% of the time.
5. Air conduction tests the whole ear system; bone conduction tests the inner ear directly.
6. The persistence of sound as it reflects off surfaces (walls) in a room.
7. The Audiometer.
8. 1000 Hz.
9. Hearing loss that occurs in both ears.
10. The technical check to ensure an audiometer’s output matches the dial settings.

Short answer type questions:

1. Describe the three main parts of an audiometer.
2. Explain the difference between Behavioral and Physiological tests.
3. What are the criteria for diagnosing Conductive Hearing Loss on an audiogram?
4. Why is 1000 Hz tested twice during an audiogram?
5. How does Play Audiometry work for children with special needs?
6. List four demographic factors collected during a case history.
7. What is ‘Masking’ and when is it used?
8. What is a ‘Flat Configuration’ in an audiogram?
9. How do environmental factors like noise and temperature affect testing?
10. Explain ‘Speech Recognition Threshold’ (SRT).

Answers:

1. The frequency dial (controls pitch), the intensity dial (controls loudness), and the interrupter switch (presents the sound).
2. Behavioral tests (like audiometry) require the patient to respond (hand raise), while Physiological tests (like ABR) measure automatic bodily responses without the patient’s help.
3. Bone conduction thresholds are normal, but air conduction thresholds are abnormal, creating a significant “air-bone gap.”
4. It is tested at the start and then repeated after testing high frequencies to ensure the reliability of the patient’s responses.
5. The child is trained to perform a fun action (dropping a block) when they hear a sound, turning the test into a game to ensure cooperation.
6. Name, age, gender, and occupation/education level.
7. It is delivering noise to the “better” ear to keep it busy while the “poorer” ear is being tested, used in asymmetrical hearing loss.
8. A pattern where the hearing thresholds are roughly the same across all tested frequencies (250 Hz to 8000 Hz).
9. Background noise can mask soft test tones (leading to false results), and extreme temperatures can make the client uncomfortable or distracted.
10. The lowest intensity level at which an individual can correctly identify and understand 50% of the speech material presented.

Long answer type questions:

1. Detail the step-by-step procedure for conducting Air Conduction testing in Pure-Tone Audiometry.
2. Compare and contrast the Rinne and Weber tuning fork tests.
3. Discuss the importance of Speech Audiometry in the rehabilitation process.
4. Explain how hearing loss is classified by degree according to Clark (1981).
5. Discuss the role of the Audiologist and the referral process based on test results.
6. Explain the Air-Bone Gap and how it is used to distinguish between Conductive, Sensorineural, and Mixed hearing loss.
7. Discuss the factors affecting the reliability of an audiometric test.

Answers:

1. Air conduction testing is the foundational method for determining an individual’s hearing sensitivity across the speech spectrum. The process follows a standardized clinical protocol:
   Preparation and Seating: The client is seated in a comfortable, sound-treated booth. It is vital they are positioned so they cannot see the audiologist’s hands or the audiometer controls to prevent visual cues from influencing the results.
   Case History and Ear Examination: Before testing, a case history is taken, and an otoscopic examination is performed to ensure the ear canal is clear of wax or foreign objects.
   Instruction Phase: Clear instructions are provided: “You will hear a series of tones. Some will be loud, and some will be very soft. Every time you hear a sound, raise your hand/finger immediately. Lower it as soon as the sound stops. Even if the sound is very faint, please respond.”
   Placement of Transducers: Headphones are placed carefully over the ears. The clinical standard is Red for the Right ear and Blue for the Left ear.
   The Testing Protocol:
   Starting Point: Testing usually begins in the better ear at 1000 Hz at an intensity of 40 dB HL (an easily audible level for most).
   Threshold Search: Using the “Down 10, Up 5” method, the intensity is decreased by 10 dB after every response and increased by 5 dB when the client fails to respond.
   Frequency Sequence: After 1000 Hz, the audiologist tests higher frequencies (2000, 4000, and 8000 Hz), repeats 1000 Hz for reliability, and then tests lower frequencies (500 and 250 Hz).
   Final Recording: The threshold—the lowest level heard at least 50% of the time—is plotted on the audiogram using ‘O’ for the right ear and ‘X’ for the left.
2. The Rinne Test: Air vs. Bone Conduction
   The Rinne test is used to compare a person’s hearing through air conduction and bone conduction within the same ear.
   To perform this test, the vibrating tuning fork is first held near the external auditory meatus to check air conduction. It is then placed against the skull behind the ear on the mastoid area to check bone conduction. The individual is asked to report which sound is louder. In a normal hearing ear, or one with sensorineural hearing loss, the sound is more audible near the external ear, a result known as Rinne-positive. Conversely, if the tone is louder through bone conduction, it indicates a conductive hearing loss, referred to as Rinne-negative.
   The Weber Test: Lateralization of Sound
   The Weber test was developed specifically to detect unilateral hearing loss (hearing loss in only one ear) by comparing bone conduction across both ears.
   In this procedure, the vibrating 512 Hz tuning fork is placed on the center of the patient’s forehead. The patient is then asked to identify whether the sound is heard in the middle of the head or if it seems louder on one side. If the sound is louder on the side where the hearing loss is present, it suggests a conductive hearing loss. However, if the sound is not louder on the side with hearing loss (meaning it is heard better in the unaffected ear), it indicates a sensorineural hearing loss.
   Summary of Findings
   The passage clarifies that the nature of the hearing loss determines how these vibrations are perceived. While a Rinne-negative result points toward a conductive issue, the Weber test helps confirm this by showing which ear specifically perceives the bone-conducted vibrations more intensely. These tests are vital for early identification, even though they should be followed by a formal audiological evaluation for a final diagnosis.
3. Pure-tone audiometry tells us if a person can hear a beep, but Speech Audiometry tells us how well they can communicate in the real world. Speech Detection Threshold (SDT): The lowest level at which a person can simply detect that someone is talking. Speech Recognition Threshold (SRT): The lowest level at which a person can identify specific words (usually spondee words). This acts as a reliability check for the pure-tone average (PTA). Speech Identification Score (SIS): This is measured at a comfortable volume. It tells the audiologist the “clarity” of the person’s hearing. For example, if a client has an SIS of 50%, a hearing aid will make sounds louder, but they may still struggle to understand words because the “brain’s processing” is damaged. Rehabilitative Utility: Speech audiometry is critical for hearing aid fitting. It helps set expectations; if SIS is very low, the audiologist knows the client may require additional support like lip-reading or FM systems, as amplification alone won’t restore clarity.
4. The degree of hearing loss is calculated using the Pure-Tone Average (PTA), which refers to the average of air conduction thresholds at 500 Hz, 1000 Hz, and 2000 Hz. The following classification outlines the relationship between the amount of loss and the resulting communication challenges: Normal Hearing (Less than 15 dB HL): Individuals in this range experience no significant difficulty in hearing or understanding sounds. Minimal Hearing Loss (16 to 25 dB HL): At this level, a person may begin to miss faint or distant speech and might struggle to understand conversations in noisy environments. Mild Hearing Loss (26 to 40 dB HL): Individuals have difficulty hearing faint speech. Communication becomes challenging when the speaker is at a distance or speaking softly. Moderate Hearing Loss (41 to 55 dB HL): A person with moderate loss can generally understand conversational speech only when the speaker is at a close distance of 3–5 feet. Moderately Severe Hearing Loss (56 to 70 dB HL): Conversations must be conducted loudly to be understood. The individual faces great difficulty following group conversations where multiple people may be speaking. Severe Hearing Loss (71 to 90 dB HL): At this degree, an individual may only hear a loud voice spoken about one foot from the ear. They may identify loud environmental noises and distinguish vowel sounds, but they struggle significantly with consonants. Profound Hearing Loss (Greater than 90 dB HL): Individuals may hear only very loud sounds. At this stage, they no longer rely on hearing as their primary channel for communication and often turn to visual methods like sign language or lip-reading.
5. The audiologist acts as the “gatekeeper” for hearing health, identifying where the breakdown in the auditory system occurs to ensure the correct treatment path. Medical Referral (ENT): If the audiogram shows a Conductive Loss (problems in the outer/middle ear) or if the client has ear pain, discharge, or a sudden loss, the audiologist refers them to an Ear, Nose, and Throat (ENT) specialist for medical or surgical intervention. Neurological Referral: If the results suggest a retro-cochlear problem (beyond the ear, involving the auditory nerve) or if there are symptoms like extreme dizziness or unilateral tinnitus, a referral to a Neurologist is made. Rehabilitative Referral: If the loss is Sensorineural and medically cleared, the audiologist recommends and fits hearing aids or cochlear implants and provides auditory training.
6. The Air-Bone Gap is the mathematical difference between the Air Conduction (AC) threshold and the Bone Conduction (BC) threshold at a specific frequency (AC – BC = ABG). Conductive Hearing Loss: BC is normal, but AC is abnormal. This creates a large ABG (usually > 10 dB). This indicates the inner ear is healthy, but sound is being blocked in the outer or middle ear (e.g., wax, fluid). Sensorineural Hearing Loss: Both AC and BC are abnormal and overlap. There is no ABG (gap is < 10 dB). This indicates the problem is specifically in the cochlea or nerve. Mixed Hearing Loss: Both AC and BC are abnormal, but AC is significantly worse than BC. There is an ABG present (> 10 dB). This indicates damage in both the conducting mechanism and the sensory mechanism.
7. A test is only as good as the conditions under which it is performed. Reliability depends on three variables: Client Factors: The client’s attention and motivation are paramount. In special education, factors like fatigue, the ability to understand instructions, and cognitive processing speed (especially in children or the elderly) can lead to inconsistent responses. Instrument Factors: Calibration is the most critical instrument factor. Audiometers must be calibrated annually to ensure the “40 dB” sound produced is actually 40 dB. Malfunctioning cords or poorly fitting headphones can also introduce error. Environment Factors: Testing must occur in a sound-treated room. Background noise can mask test tones, leading to a “false” higher threshold. Reverberation (echo) and even room temperature can distract the client, reducing their focus on the faint signals.