Exam 1 Flashcards
What range of frequencies can humans hear?
20 - 20,000 Hz
1 Hertz = 1 ____ per _____
cycle/second
What range of intensity/pressure levels can humans hear?
0 - 120 dB
What is the period of a sound?
The time the wave takes to complete one cycle.
How are frequency and period relateed?
Indirectly
Pitch
Psychological correlate of frequency
- Measured in mels
- Directly related to frequency
Loudness
Psychological correlate of intensity/pressure
- Measured in phons/sones
- Directly related to intensity/pressure
Simple sounds
Frequency specific (only one frequency)
Ex: puretones
Complex sounds
Many frequencies
Ex: speech and noise
Complex periodic sounds
Has fundamental frequency
- All other tones are harmonics of it
- Ex: voiced speech sounds
Complex aperiodic sounds
No fundamental frequency or harmonics
- Ex: voiceless speech sounds
What is the purpose of puretone audiometry?
To determine:
- degree and
- type
of hearing loss.
What are the two types of measurement in puretone audiometry?
- Air conduction threshold
- Bone conduction threshold
Conductive vs. sensorineural vs. hybrid hearing loss
- Conductive: outer and/or middle ear
- Sensorineural: inner - cochlea and/or nerve
- Hybrid: both
What is the purpose of speech audiometry?
To validate puretone audiometry
- More power/validity since we hear speech in real life
For accurate differential diagnosis
- Where the problem is in the ear
What are the two measurements in speech audiometry?
- Speech reception threshold
Speech discrimination score
What is the purpose of tympanometry?
To objectively (no patient participation) assess the middle ear function
Tympanogram
Graphical plot of the eardrum mobility at different air-pressure values
Behavioral Observation Audiometry (BOA)
Subjective assesment for ~6 mos - 3 yrs population
- Sounds presented through speakers
- Effective with visual reinforcement (must be able to turn their head)
- Tests localization
Play audiometry
Subjective assessment for 3-5 population
- For a/c and b/c threshold assessment
- Play a game where child completes a task after each sound
Otoacoustic Emissions (OAEs)
Objectively evaluate the inner ear/cochlear (OHC) function
- Very fast - <5 min/ear
- Present clicking sounds, read echoes coming away from hair cells, look @ amplitude
Auditory Brainstem Response (ABR)
Objectively evaluates auditory nerve & brainstem function
- Preceded OAEs
Immittance Audiometry
Objective assessment that preceded ABR
- Directly evaluates middle ear status
- Indirectly evaluates inner ear status (stapedius function)
- Includes tympanometry
Audiogram
Graphical plot of a/c & b/c thresholds across puretone frequencies
Audiometer
Electronic device for hearing assessment
Audiometry
Procedure for hearing assessment
Ex: speech or pure tone
Hearing Threshold Level (HTL)
- Lowest level you can hear 50% of the time (2/4)
OR
- lowest level you can hear 3 out of 4 times
OR
- Lowest level you can hear 3 repeated times
- Whichever comes first*
External/Middle ear function
Conducts sounds to the inner ear
Inner ear function
Sound analysis & discrimination
- does complex Fourier analysis
Air Conduction Audiometry: device
Pure tone Audiometer
Air Conduction Audiometry: purpose
- Obtain a/c thresholds across audiometric frequencies
- Compute pure tone average (PTA)
- Compute degree/extent of hearing loss
Air Conduction Audiometry: procedure
- Frequency sequence: 1, 2, 4, 8, 0.25, 0.5, and 1 kHz
- Initial intensity dial setting: 30 dB
- Starting ear: better ear or right ear
- Threshold level: 50% correct or 3 repeated responses
Air Conduction Audiometry: symbols for plotting a/c thresholds
The pure tone average (PTA) tells you the _____ of hearing loss.
degree
PTA (PTA1)
Average of a/c thresholds at 500, 1000 & 2000 Hz
PTA2
Average of a/c thresholds at 1000, 2000, and 4000 Hz
Two Frequency Average/Fletcher Average
Average of best a/c thresholds @ two frequencies between 500, 1000 and 2000 Hz
Hearing loss classifications for children 5 and under
0-15 dB HTL - Normal
16-30 dB HTL - Mild
31-50 dB HTL - Moderate
51-80 dB HTL - Severe
>81 dB HTL - Profound
Hearing loss classifications for children older than 5 & adults
0-25 dB HTL - Normal
26-40 dB HTL - Mild
41-55 dB HTL - Moderate
56-70 dB HTL - Moderate-Severe
71-90 dB HTL - Severe
>91 dB HTL - Profound
When do we test mid-octive frequencies?
When the difference between two octaves tested (e.g., 1,000 and 2,000 Hz) is ≥20 dB
What is the maximum acceptable difference between test-retest thresholds?
10 dB
Symbols for plotting bone conduction threshold levels
masked are brackets []
Procedure for audiometric threshold
Start @ 30 dB:
- If correct, do down 10 up 5:
- If correct, go down 10
- If that’s incorrect, go up 5
- Continue until you reach threshold
- If no response, go to 50 dB
- Move up in 10 dB steps until you get a response
- When you get a response, do down 10 up 5 procedure until you get threshold
What is the purpose of bone conduction audiometry?
- Evaluates the inner ear status
- Helps us make a differential diagnosis of the site of pathology
Procedure for bone conduction audiometry
- Test at 1, 2, 4, .25 and .5 kHz (no retest)
- Start at 30 dB
- Placement: mastoid
Normal B/C thresholds
- 0-5 yrs: 0 to 15 dB across 250-4,000 Hz
- 5+ yrs: 0 to 25 dB across 250-4,000 Hz
How will a/c and b/c thresholds differ for people with sensorineural, conductive, or mixed hearing loss?
- Sensorineural: a/c and b/c both abnormal, equally affected
- Conductive: a/c normal, b/c abnormal
- Mixed: a/c and b/c both abnormal, a/c worse (passes through two damaged areas)
What is Interaural Attenuation (IA)?
AKA cross hearing. Refers to loss of sound energy as test travels from the test ear to the nontest ear
- for A/C, IA = 40 dB
- for B/C, IA = 0 dB (no loss of energy)
When & how much masking: air conduction
Mask if:
- unmasked AC threshold in the test ear - 40 dB (IA) ≥ the unmasked BC threshold in the non-test ear
How much:
- Minimum masking = unmasked AC threshold in the nontest ear
When & how much masking: bone conduction
Mask if:
- Air-Bone gap in the test ear ≥ 10 dB
How much:
- Minimum masking = Unmasked AC threshold in the non-test ear + Occlusion Effect (freq. dependent)
When do we use the occlusion effect?
With normal or sensorineural loss.
Puretone audiometric criteria for Normal Hearing
- A/c & b/c within 15 or 25 dB (age dependent)
- A/c = b/c
- Air-bone difference ≤ 10 (clinically insignificant)
Puretone audiometric criteria for Conductive Loss
- B/c = normal
- A/c = abnormal
- A/c ≠ B/c
- Air-bone difference > 10 (clinically significant)
Ex: otitis media
Puretone audiometric criteria for Sensorineural Loss
- A/c = abnormal
- B/c = abnormal
- A/c = B/c
- Air bone difference ≤ 10 (clinically insignificant)
Ex: Presbycusis (age-related sensorineural loss)
Puretone audiometric criteria for Mixed Loss
- A/c = abnormal
- B/c = abnormal
- A/c ≠ B/c
- Air bone difference > 10 (clinically significant)
Ex: Presbycusis + otitis media
ASHA guidelines for hearing screening
- 1, 2, and 4 kHz at 20 dB HL
- Criteria: child fails if he/she fails to respond @ any frequency in either ear
