Dr kavitha ashok kumar

FINGER FRICTION TEST

WATCH TEST

SPEECH /VOICE TESTS

Normal person hears a conversation at 12m/40ft

Hears whisper at 6m/20ft in quiet surroundings

(disadv:lack of stardardisation of pitch,intensity)

TUNING FORK TESTS

It is the study of hearing disorders through hearing evaluation and rehabilitation

Acoustics:refers to hearing and perception of sound

Sound:is a form of energy,which is produced by any vibrating object.

Velocity of sound in air is 344m/sec

Sound travels faster in solids >liquids>gas

Frequency:is the number of cycles /sec. Its unit is Hertz (Heinrich Rudolf Hertz).

Ear is sensitive—20-20000Hz,speech frequency-500-3000Hz,audiometric testing-125-8000Hz

Pitch is the subjective sensation produced by frequency.

Intensity is the strength of sound and determines the loudness of sound. Its unit is decibel (dB) (Alexander Graham Bell)

whisper----30dB conversation---60dBshouting-----90dBPain in the ear---130dB

Pure tone: a single frequency sound

Complex sound: more than one frequency

Music : is a peroidic complex sound

Noise: is a aperoidic complex sound

1. White noise-all frequencies of sound

Narrow band noise – certain frequencies of sound

Speech noise-speech frequency sounds(300-3000Hz)

Loudness discomfort level:90-150dB.It is

important while prescribing a hearing aid.

Dynamic range :is the difference between the

most comfortable level and the loudness

discomfort level

Masking: is a phenomenon to produce inaudibility

of one sound by the presentation of another

Essential for bone conduction tests and air conduction tests when

the difference in hearing between the ears is>40dB

Measurement of hearing acuity

Types:

Pure tone audiometry (PTA)

Impedence audiometry

Speech audiometry

Otoacoustic emissions(OAE)

Brain stem evoked response audiometry (BERA)

Other audiological tests

Tests for recruitment◦ ABLB(alternate binaural loudness balance test)

◦ , SISI(short increment sensitivity index)

Tone decay test

Eustachian tube function tests

Measurement of hearing acuity by estimation of air conduction and bone conduction thresholds of hearing for various frequencies using pure tones

Pure tone- 125-8000Hz(AC)250-4000Hz(BC)

Threshold of hearing: Minimum perceivable intensity of sound

Is an electronic device that generates pure tones.The intensity of these tones can be increased or decreased in 5dB steps

Air conduction- sound is presented adjacent to pinna- conduction through external and middle ear.

Bone conduction- sound presented on the mastoid process- directly stimulates the inner ear.

The threshold for air and bone conduction for each frequency is noted .

Bone conduction is a measure of the cochlear function

The difference in the thresholds of air and bone conduction(A-B gap)is a measure of degree of conductive deafness.

In a normal person,both air and bone conduction is at 0dB and A-Bgap is absent

Pure tone average :is an average of the air conduction thresholds at 500,1000 and 2000Hz (speech frequencies)

Masking :air conduction sounds cross over when >40dB difference exists between the AC thresholds of the two ears whereas BC sounds may crossover at even 0dB difference.A narrow band noise is given to the non test ear (better ear).This is called masking.

Normal

Normal BC thresholds

Increased AC thresholds

AB gap Usually lower

tones affected Loss usually

<60dB

Both air and bone conduction thresholds are raised- No AB gap

Bilateral sloping (decending) curve in presbyacusis

OTOSCLEROSIS

Noise induced hearing loss

Tests various frequencies

Both qualitative and quantitative (type and severity of hearing loss)

Documentation

Compare serial audiograms/ pre and post treatment audiograms

May give clue to diagnosis

Subjective test Patient should understand instructions-

cannot be done in children and psychiatric patients

Not accurate for medico-legal purposes if malingering suspected

Masking to be done to avoid involvement of non-test ear in the test

Impedance = resistance Impedance X compliance Measurement of the compliance of the middle

ear structures to the sound impulse More compliance= middle ear structures

vibrate more freely Less compliance= middle ear structures

vibrate less freely (more stiff)

Tympanometry: measurement of compliance of middle ear structures to sound impulse at varying external ear pressures

Stapedial reflex/ Acoustic reflex :can be documented as there is reduced compliance during contraction of stapedius muscle (normal stapedial reflex threshold: 90dB)

Objective test Easy to perform even in children Fast results- best screening test Diagnose various middle ear diseases Stapedial reflex studies help in◦ Facial nerve lesions◦ Auditory acuity in children◦ Recruitment◦ Malingering

Speech reception threshold(SRT)◦ Minimum intensity at which 50% of spondee words

(bisyllables with equal stress on each syllable )are repeated correctly

◦ Normal:10dB of PTA

Speech discrimination score(SDS)◦ Percentage of correctly repeated phonetically

balanced words(single syllable words)given at an intensity 30-40dB above the SRT.

◦ Normal: 95-100%◦ Conductive hearing loss:90-100%◦ Sensorineural hearing loss: is poor

Are sounds

Originate from cochlea

Two types

1. Spontaneous

2. Evoked

- Transient

- Distortion

Done in quite room

No patient preparation

Requires 10 -15 minutes

Probe placed in the ear canal

Not painful

Non-invasive

Uses:

Screening test in neonates,uncooperative and mentally challenged patients

Helps to distinguish between cochlear and retrocochlear hearing loss

Recording of the electrical activity of the auditory pathway till the brain stem evoked by a sound stimulus

1 2 3 4

5

.

Brain stem evoked response audiometry (BERA)

• Objective way of eliciting brain stem potentials in response to audiological click stimuli

• Waves are recorded by electrodes placed over the scalp

• BERA is resistant to the effects of sleep, sedation and anesthesia

Objective measure auditory acuity

Can be done even in new born children

Authentic for medico-legal purposes-malingering

Site of the lesion in auditory pathway can be detected depending on the latency of individual waves

What is Bing’s test?

What is Gelle’s test?

Why do we use 512Hz tuning fork for TuningFork Tests?

What is roll over phenomenon?

What is the significance of acoustic reflex?

What is carhart’s notch?

Which frequency is most affected in noise induced hearing loss?

1)In impedence audiometry:

1. “A” wave denotes otosclerosis

2. Patient’s cooperation is essential

3. A 220Hz frequency probe is used

4. “C” wave denotes ossicular discontinuity

5. “B” Wave is seen in serous otitis media

2) Tuning fork tests:

1. Is a subjective test

2. Quantifies the hearing loss

3. Can detect maligering

4. Are clinical tests

5. Detects the type of hearing loss

3) Rinnes test is

1. Negative in acoustic neuroma

2. Positive in Meniere’s disease

3. Negative if minimum deafness is 15-20dB

4. Positive in normal individual

5. Done with 512Hz tuning fork

4)Pure tone audimetry is:

1. Objective test

2. Helps in documentation

3. Ideally performed in a sound proof room

4. “X” symbol is used to mark air conduction in left ear

5. Can differentiate between cochlear and retrocochlear hearing loss

5)Otoacoustic emissions is:

1. invasive

2. an objective test

3. Done in only adults

4. Used to screen for hearing loss

5. Helpful to diagnose cochlear deafness