Chapter 20

Assessment of Sensory Acuity

Why Assess Sensory Acuity?

• Student impairments do not always require extensive assessment– Seemingly complex academic and behavioral

problems may be rooted in sensory difficulties

• Most common sensory difficulties– Vision– Hearing

Vision Difficulties

• Types of visual impairment– Visual acuity• Clarity or sharpness of vision (20/20 v. 20/10 vision)

– Field of vision• Tunnel vision• Scotoma

– Imperfect color vision• Discrimination between hue, saturation, and brightness

Visual Acuity

• Most serious as an educational problem if impairment occurs prior to age 5

• 5-33% of students are considered to be along the broad spectrum of “visually handicapped”– Blind– Low vision– Visually limited

Visual Acuity

• Signs of visual impairment – Frequent headaches, dizziness, sensitivity to light,

blurred vision– Obvious physical signs (e.g. red, swollen, or crossed

eyes; haziness in pupils)– Behaviors:

• Holding books too close to face while reading• Abnormal tilting of head• Poor alignment of words• Reluctance to participate in games requiring distance vision

or visual accuracy

Vision Screening and Assessment• Screening

– Standard Snellen Wall Chart• Limitations with school-age population• Referral rule of thumb:

– 20/40 in either eye for K-3 children– 20/30 in either eye for older children

– Snellen E Test• Used with children who are unable to rea

– Keystone Telebinocular• Both Snellen tests are somewhat restricted in focus• Assesses 14 different visual skills

• If visual assessment done by trained professionals indicates a deficiency, schools must engage in tests to inform intervention

Vision Screening and Assessment• Low-vision results from differing visual disabilities– Disabilities interact with:

• Individual differences• Environmental differences

– A need for more comprehensive and informative vision assessments

• Clinical low-vision exams• Functional-vision assessment• Learning-media assessment – Developing tools for reading and writing)

• Braille Assessment Inventory (BAI)– Developed to assess need for Braille instruction

Hearing Difficulties • Signs of hearing loss

– Failure to pay attention or frequently ask to have things repeated

– Both may not occur in a quiet context – Frequent medical problems– Demographic risk variables:

• Low SES• Cleft palate or Down syndrome • Native Americans and Eskimos

• Educators should be quick to screen for hearing difficulties if any warning is given– If a problem is detected, further referral is necessary

• Otologist: Expertise in physical examination of ears• Audiologist: Expertise in hearing assessment and rehabilitation

Screening and Assessment • Modes of hearing– Air conduction – Bone conduction

• Screening tests tend to measure air conduction while diagnostic tests may measure both

• Types of screening– Three components:

• Initial screening• Follow-up hearing threshold tests• Referral

– All states have laws for screening school-age children; however, pre-K programs are not required to screen

Screening and Assessment

• Hearing screening– Objective– Conducted individually – Screening should include:

• Case history and visual inspection of ear

• Pure-tone hearing screening• Tympanometry

• Hearing-threshold screening– More detailed– Used to determine the

lowest hearing level at which the child can respond to a minimum of 2 of 3 pure tones

Screening and Assessment

Screening and Assessment

Screening and Assessment

• Tympanometry Screening – Better control over some extraneous variables– “Middle-ear screening”– Goal is not to identify educationally significant

hearing loss, but to identify children with middle-ear disorders• E.g. children with middle ear disorders may be able to

function normally in an educational setting

Other Hearing Tests

• Multiple tests are often needed to identify the type of hearing loss

• Two additional tests might include:– Speech Recognition Threshold (SRT)– Word Recognition Score (WRS)

Types of Hearing Loss

• Conductive hearing loss– Bone conduction hearing is normal but air

conduction hearing is impaired – May be due to build up of wax or fluid; build up of

fluid in middle ear is most common in children• “Otis media”

• Sensorineural Hearing Loss– Dysfunction of the inner ear– May be due to noise exposure, inheritance,

ototoxic drugs, mumps, measles, or head trauma

Types of Hearing Loss

• Mixed hearing loss– Combination of conductive and sensorineural

• Central auditory hearing loss– Children may pass many typical hearing exams– Problems filtering out background noise and/or

with short- and long-term auditory memory• Likely to be educationally significant

Hearing Loss

• Determining severity– Insert Figure 20.7 [there is no such figure in book]

Speech Understanding and Hearing Loss

• Conductive hearing loss– Hear normal conversational speech, but at a very

reduced level

• Sensorineural hearing loss– Hearing loss tends to decrease as the sound

frequency increases• May hear low-frequency vowel sounds but struggle to

hear high frequency consonant sounds• Particularly problematic in noisy environments