Basic Audiology

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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250Hz 500Hz 1000Hz 2000Hz 4000HzFrequency

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.


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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.


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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.


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Intensity

RightLeft

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Inte

nsity AIR

BONE

Interpretation

Conductive

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Inte

nsity AIR

BONE

Interpretation

Sensorineural

Interpretation

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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

Documents

Basic Audiology