Audiology Past Paper PDF

1. Pathways of Sound Air Conduction (AC): Sound travels through the outer ear to the cochlea via the tympanic membrane and middle ear. AC thresholds indicate the overall hearing loss (HL), incorporating conductive and sensorineural components. Bone Conduction (BC): Sound bypasses...

1. Pathways of Sound Air Conduction (AC): Sound travels through the outer ear to the cochlea via the tympanic membrane and middle ear. AC thresholds indicate the overall hearing loss (HL), incorporating conductive and sensorineural components. Bone Conduction (BC): Sound bypasses outer/middle ear, vibrating directly through the skull to the cochlea. BC thresholds reveal the sensorineural component of HL. Conductive pathologies do not impact BC thresholds. 2. Air and Bone Conduction Testing Air Conduction (AC) Testing: ○ Tests range: 250 Hz - 8 kHz. ○ Uses supra-aural or insert earphones for ear-specific thresholds. Bone Conduction (BC) Testing: ○ Frequency range: 250 Hz - 4 kHz. ○ Uses a bone vibrator, stimulating both cochleas simultaneously. ○ No interaural attenuation (IA), meaning both ears can respond. 3. Audiogram Interpretation Types of Hearing Loss (HL): ○ Conductive HL: Normal BC, but AC shows significant ABG (>12 dB). ○ Sensorineural HL (SNHL): BC not within normal limits (WNL), no significant ABG. ○ Mixed HL: BC not WNL, significant ABG present. Air-Bone Gap (ABG): ○ AC - BC. Significant if >12 dB, indicating conductive loss. 4. Masking in BC Testing Purpose: Ensures responses are from the test ear, not the non-test ear. When to Mask: Significant ABGs in any frequency. Procedure: Noise is delivered to the non-test ear (NTE) to obtain an accurate response from the test ear. 5. Crossover and Cross-Hearing Crossover: Sound presented to the test ear (TE) can reach the non-test ear (NTE). Cross-Hearing: When the crossover signal is audible in the NTE. Masking is used to prevent the NTE from responding to the crossover signal.  Interaural Attenuation (IA): ○ AC: Minimum IA of 40 dB for supra-aural, 70 dB for insert earphones. ○ BC: Virtually no IA, so masking is crucial in BC testing. 6. Degree of Hearing Loss Mild: 26-40 dB HL Moderate: 41-55 dB HL Moderately Severe: 56-70 dB HL Severe: 71-90 dB HL Profound: >90 dB HL Key Concepts to Remember: ABG helps identify conductive components in HL. Masking isolates ear responses to accurately assess hearing thresholds. Crossover and Cross-Hearing are managed by IA values specific to the type of earphone or transducer. 1. Basic Hierarchy of Auditory Skills Development Detection: Awareness of sound. Discrimination: Recognizing if two sounds differ (e.g., “ee” vs. “ah”). Identification: Associating meaning with a sound (e.g., “moo” with a cow). Comprehension: Understanding words, phrases, and sentences, and responding or following directions. 2. Complete Audiological Evaluation Components: ○ Case History: Patient’s complaints, symptoms, hearing self-assessment, potential hearing loss causes, medical and rehabilitation history. ○ Otoscopy: Examining the ear canal and tympanic membrane. ○ Immittance Testing: Assessing middle ear function. ○ Degree and Type of Hearing Loss: Identifying the severity and type (conductive, sensorineural, or mixed). ○ Speech Testing: Checking speech perception. ○ Counseling & Recommendations: Sharing results and next steps. 3. Pure Tone Audiometry Factors Affecting Hearing Thresholds: ○ Methodological: Test environment and instructions. ○ Physiological: Ear and auditory pathway health. ○ Psychological: Patient’s alertness and responses. ○ Physical: Earphone fit and equipment accuracy. ○ Environmental: Background noise. 4. Pure Tone Testing Procedure Instructions: Patient is instructed to respond when they hear a tone. Setup: ○ Seating: Front, back, or side-facing. ○ Earphones: Standard or insert earphones. ○ Response Modes: Patient can respond by hand, verbally, or pressing a button. Testing Frequencies: 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz. Hughson-Westlake Procedure: Adjusting tone intensity up by 5 dB if no response and down by 10 dB when a response is given, to find the hearing threshold. 5. Air Conduction Audiometry Purpose: Determines the degree of hearing loss affecting the entire auditory pathway. Testing Process: ○ Start at 1 kHz, 30 dB HL, adjusting based on response. ○ Establish thresholds for each ear at all test frequencies, using interoctave frequencies if there is a 20 dB difference between adjacent frequencies. Recording Results: ○ Right ear (AC) threshold is marked as “O,” and left ear as “X.” Pure Tone Average (PTA): ○ Calculated by averaging 500 Hz, 1 kHz, and 2 kHz thresholds. ○ PTA can indicate the degree of hearing loss and communication impact. 6. The Audiogram Axes: ○ Frequency (Pitch): Vertical lines from low to high pitch (125 Hz to 8 kHz).  ○ Intensity (Loudness): Horizontal lines from soft to loud (0 dB HL to 120 dB HL). Thresholds: ○ Lowest sound level a person can hear at each frequency is plotted as their threshold. ○ Normal Hearing: Adults: -10 dB HL to 25 dB HL. Children: -10 dB HL to 15 dB HL, with 16-25 dB HL considered slight/minimal loss. Speech Banana: An area on the audiogram representing the frequencies and intensities typical for human speech sounds. 7. Degree of Hearing Loss Classification: ○ Mild: 26-40 dB HL – Adults may struggle with soft speech; children may have language learning difficulties. ○ Moderate: 41-55 dB HL – Hearing aids are often beneficial; visual cues aid understanding. ○ Moderately Severe: 56-70 dB HL – Speech sounds inaudible at normal conversation levels. ○ Severe: 71-90 dB HL – Difficulty hearing loud speech; hearing aids or implants may help. ○ Profound: >90 dB HL – Limited benefit from hearing aids; cochlear implants may be considered. 8. Types of Hearing Loss Conductive: Affects outer/middle ear; AC thresholds are worse than BC thresholds. Sensorineural (SNHL): Inner ear or auditory nerve damage; similar AC and BC thresholds. Mixed: Both conductive and sensorineural components; shown by significant differences between AC and BC. Masking in AC and BC Testing AC Masking: Needed if the AC threshold in the test ear is louder than the non-test ear’s bone conduction threshold by more than 40 dB (supra-aural) or 70 dB (insert earphones). BC Masking: Necessary when there is an air-bone gap (ABG) >10-15 dB since bone conduction has almost no interaural attenuation. 2. Types of Hearing Loss Conductive HL: Normal BC, poor AC (significant ABG). Sensorineural HL (SNHL): Poor AC and BC with no ABG. Mixed HL: Both AC and BC poor with a significant ABG. 3. Hughson-Westlake Procedure Start at 1 kHz and 30 dB HL. Decrease by 10 dB if they hear it; increase by 5 dB if they don’t. Repeat until threshold (softest audible level) is found. 4. Speech Testing (Details pending) Checking speech perception. Measures speech recognition and understanding at various loudness levels, useful for evaluating real-world hearing abilities. 5. Interaural Attenuation (IA) Sound reduction as it crosses from the test ear to the non-test ear is key for determining masking needs (40 dB for supra-aural, 70 dB for inserts). 6. Crossover and Cross-Hearing Crossover: Sound from the test ear reaches the non-test ear. Cross-Hearing: When this crossover sound is heard by the non-test ear; masking prevents non-test ear response.