Basic Audiology Norberto V. Martinez, M.D. Professor Faculty of Medicine and Surgery University of Santo Tomas
Basic Audiology
Norberto V. Martinez, M.D.Professor
Faculty of Medicine and SurgeryUniversity of Santo Tomas
Philippine Pediatric Society, Inc.Recommendations for Preventive
Pediatric Health Care 2002
Hearing Screening• At birth to 3 months7
• Objective/subjective hearing screening8
7 endorsed by the Philippine Society of Otorhinolaryngology – Head and Neck Surgery8 AAP Task Force on Newborn and Infant Hearing Loss
Hearing Impairment is the single most common condition affecting newborns
1-3 per 1000 in well-baby2-4 per 100 in the NICU
High Risk Registry
A pgar score < 5 in 5 minutes
B acterial meningitis
C ongenital infection (TORCH)
D efects of head and neck
E levated bilirubin level
High Risk Registry
F amily history
G ram weight < 1500grams
H istory of NICU enrollment
I ntake of ototoxic drugs
Auditory Milestones
Age (in months)
Description
0 - 3 -startles at a loud sound or noise-stops moving or crying when you call
3 - 6 - turns head or move eyes to a familiar sound
6 - 10 - responds to his/her own voice
Auditory Milestones
Age (in months)
Description
10 - 15 -Repeats simple words and sounds you make
15 - 18 - Understand simple phrases and can point to body parts
18 - 24 - should have at least 150 spoken vocabulary
Behavioral Observation Audiometry
• Used in testing children from birth to 8 months
• Requires two clinician (1 distracts and observes; 1 present the stimulus)
• Toys, noisemakers or phonemes represenative of different frequencies may be used
Behavioral Observation Audiometry
Some expected behavioral responses- Startle reflex- Auropalpebral reflex/Eye-blink Reflex-Eye movements- Head movements
Visual Response Orientation Audiometry
• In the first stage the audiologist positions the infant so that it is looking straight forward. Next, a sound will be made to the child side, and the audiologist checks to see if the child turns to the direction of the noise. This indicates that the child has heard the sound.
• This is repeated as the sound gets softer. To ensure that the child makes the effort for the quieter sounds, the child is rewarded with a puppet show for each successful head turn.
Visual Reinforcement Observation Audiometry
Some observable responses- head turn toward the sound- Head turn toward visual reinforcer- Change in facial expression- Cry- Vocalize response
Play Audiometry
• Use in testing 2 to 5 years of age
• Child is conditioned to respond by accomplishing a task which is usually in the form of a play
Play Audiometry
Modes of responses:- Dropping- Hitting- Stacking- Throwing- Pushing buttons- Building
Degree of Hearing LossNormal Hearing Level
• 0-25dB
• Can hear all sounds
Degree of Hearing LossMild Hearing Loss
• 26-40dB
• Will miss consonants. At 30 dB can miss 25-40% of speech signal. Degree of difficulty depends on noise level, distance from speaker, and configuration of the hearing loss. Will benefit from hearing aid
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100110120
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Intensity
RightLeft
Degree of Hearing Loss
Degree of Hearing LossModerate Hearing Loss
• 41- 60dB
• Can understand face-to-face conversation at a distance of 3-5 feet is structure and vocabulary is controlled. May miss 50-75% of a spoken message is the pure tone average is 40 dB. Will benefit from hearing aid.
Degree of Hearing Loss
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Intensity
RightLeft
Degree of Hearing LossSevere Hearing Loss
• 61- 80dB
• May not even hear voices, unless speech is very loud. Without amplification, the individual will not recognize any speech through listening. Can be a candidate for cochlear implantation or hearing aids.
Degree of Hearing Loss
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Intensity
RightLeft
Degree of Hearing LossProfound Hearing Loss
• 61- 80dB
• May not even hear voices, unless speech is very loud. Without amplification, the individual will not recognize any speech through listening. Can be a candidate for cochlear implantation or hearing aids.
Degree of Hearing Loss
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Intensity
RightLeft
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100110120
250Hz 500Hz 1000Hz 2000Hz 4000HzFrequency
Inte
nsity AIR
BONE
Interpretation
Conductive
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Inte
nsity AIR
BONE
Interpretation
Sensorineural
Interpretation
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250Hz 500Hz 1000Hz 2000Hz 4000HzFrequency
Inte
nsity AIR
BONE
Mixed
Speech Audiometry
• May be used in testing children approximately 1 to 5 years of age
• Speech stimuli should be appropriate for their language skills
Examples of Speech Stimuli
• Body parts• Naming/ pointing of pictures or objects• Ling Six Sounds
/a/, /u/, /i/, /s/, /sh/, /m/Spondees- to syllable words with equal
stress Eg. Hotdog,cowboyAsking questions
For Children 6 months to less than 5 years of age
Using noise makers
For Children 6 months to less than 5 years of age
Clapping Your Hands
For Children 3 to 5 years old
Ask the child to speak simple words after you
For Children 3 to 5 years old Pointing tasks
Auditory Evoked Reponse
• AER - is an activity within the auditory system produced or stimulated by sound
• Two processes essential for detecting AER: 1. Amplify the voltage - 100,000 x 2. Signal averaging noise - EEG, electrical and muscle activity movement of the jaw or neck
Otoacoustic Emissions
• Sounds generated by the cochlea that can be measured in the external auditory canal
• Produced by the motile activity of the outer hair cells
Using signal averaging techniques, the AudioPath separates the third tone from all other sounds within the
ear canal and displays the data on graphical display
Acoustic Reflex
• The lowest intensity of an acoustic stimulus at which minimal change in the middle ear compliance can be measured
• ART for normal hearing subjects is 70dB to 100dB
Hearing Aid Block Diagram Volume Control Microphone Amplifier Receiver Battery
Behind-the-ear Hearing Aids
• Connected via earhook and tubing to earmold
• Earmold easily replaceable as required
• More comfortable and less cumbersome than body aid
How a cochlear implant works
TEMPO+ Processor
2. Speech processor
codes it into a signal of electrical
pulses
3. Signal sent to headpiece
4. Signal transmitted
across skin to implant
5. Implant sends signal to electrodes in the cochlea
6. Auditory nerve picks up
signal and sends it to the
brain
7. Brain recognize
s this signal as sound!
1. Sounds picked up
by microphone