Auditory and visual assessment

Hearing traditionally is assessed with tones produced by an audiometer. An audiogram shows the weakest tones that a person can detect at different frequencies.

Vision traditionally is assessed with black letters printed on a white background (e.g. a Snellen Chart).  Visual acuity refers to the smallest letters that a person can identify.

New procedures can be used to evaluate whether a person can hear or see well enough to participate in face-to-face conversation.  How are these procedures different?

• speech is the stimulus
• the environment is realistic
• both hearing and vision are assessed

Vision impairment

Most people with impaired hearing compensate by watching the speaker’s mouth movements, facial expressions, and gestures.  A vision disorder can significantly limit the person’s ability to understand speech.

Vision impairment (e.g., cataract, glaucoma, macular degeneration, diabetic retinopathy) is common in older people.  A person with a vision loss may experience one or more of the following difficulties:

• reduced ability to see small objects
• reduced clarity of objects
• reduced sensitivity to brightness contrast
• limited visual field
• reduced ability to distinguish colors
• increased interference from glare

Simulation of vision loss

It is hard to imagine the experiences of a person with impaired vision, but it is possible to simulate vision loss.  Some simple methods for simulating the effects of vision loss include the use of "plus" lenses to blur images, goggles to restrict the visual field, glass or plastic filters to diffuse light, or computer-based software.  For example, you can use Adobe "Photoshop" to illustrate what a person with impaired vision might see during face-to-face communication:

Visual perception of facial cues

Many visible cues are important for face-to-face communication: the speaker's head movements (acknowledgement, agreement); mouth movements (vowels, consonants); and eye movements (attention, turn-taking).  A simple test can be used to evaluate a person's ability to see these details. The examiner sits at a 1-meter distance, faces the light, and presents a set of head movements (up-down; right-left), mouth movements (the vowels /u/, /a/, /i/; the consonants /l/, /f/, /th/), and eye movements (open-shut, front-side).  The person is asked to watch carefully and name each one. Results from 40 older people are summarized below, as a function of each person's better-eye visual acuity (H = head movements; M = mouth movements; E = eye movements; PL = perception of light only; NPL = no perception of light).  Note that perception of facial cues by people with intermediate visual acuities (about 6/36 to 6/90) cannot be predicted from their perception of test letters.  This group includes those with 6/60 visual acuity ("legal blindness").  [For more information, see: Erber and Osborn, 1994; Erber and Heine, 1995; Erber, 2002]

Adaptive assessment of sentence perception (Sent-Ident)

During conversation, a person may misunderstand and require repetition, clarification, amplification, and/or visible cues.  To assess a person's needs, the examiner sits at a 1-meter distance, faces the light, and speaks simple sentences (e.g., "Her father put the milk on the table").  If a sentence is not heard correctly, the examiner says it again, under progressively easier conditions (repetition, clarification, one word visible, all words visible) until it is identified correctly.  Five sentences are spoken without amplification, and five are spoken while the person listens through hearing aids or an amplifier/earphones.  The results for 24 older people who initially obtained a score of 1/5 without amplification are shown above, as a function of amplification and successive test conditions (O = original presentation; R = repetition; C = clarification; 1V = one word visible; AV = all words visible).  Note that these 24 people obtained benefit from both amplified sound and partner cooperation.  [For more information, see:  Erber, 1992, 2002; Erber and Heine, 1995].

Benefit from Amplification

Many older people with impaired hearing do not own or use hearing aids.  Regardless, they may benefit from amplification of sound.  Student therapists engaged 248 older people in face-to-face conversation on familiar topics while these people either listened unaided or through a small amplifier/earphones.  In each case, the communication partner held the microphone close to the mouth but not obscuring it. Conversational fluency was rated on a 4-point scale (/1/ = low; /4/ = high).  Each box in the matrix (below) compares rated conversational fluency under the two listening conditions.  In many cases, people obtained conversational benefit  when they listened to amplified sound.  [For more information, see: Erber, 1994, 1996, 2002]

Conversational fluency:  Effects of distance and amplification

The intensity of airborne sound is reduced as a function of distance.  A therapist talked face-to-face with an older person under three different conditions (portable amplifier/ALD, hearing aids, no amplification) and six different distances from 0.5 to 3.0 meters.  She rated the fluency of each conversation on a 4-point scale (/1/ = low; /4/ = high).  When she used a portable amplifier with a long earphone cord (with the microphone near the mouth) high conversational fluency was obtained throughout this range of distances.  Hearing aids were superior to unaided hearing, but conversational fluency diminished with distance for both conditions.  The benefits of near distance and amplification are evident.  [For more information, see: Erber, 1996; 2002; Erber, Holland, and Osborn, 1998]

"Instant Therapy": Effects of situation and environment

"Instant Therapy" is any situational change that immediately improves a person's ability to communicate.  To provide instant therapy, simply modify the conditions while conversing with the person, and rate the fluency of conversation under each condition.  Assign a number from /1/ (low) to /4/ (high).  You may compare effects of amplification, voice level, distance, rate of speech, the environment, and so forth.  In this example, a therapist modified the situation (amount of noise, reverberation, illumination, and glare) for an older person in a nursing home.  The person experienced great difficulty in the noisy and distracting dining room (conversational fluency rating = 1).  She could converse more easily in her own bedroom, which was quiet and less distracting (conversational fluency rating = 4).  [For more information, see:  Erber, 1996, 2002]

DYALOG conversation analysis

You may use a computer and DYALOG software to objectively measure the fluency of conversation before, during, and after any type of communication therapy.

To use DYALOG software, observe the child or adult in conversation (live or recorded).  Simply press the "space bar" on the computer keyboard whenever a misunderstanding occurs and "repair" (e.g., repetition, clarification) is needed.  Release the space bar when fluent conversation is restored.  At the end of the conversation (or after a specified number or minutes), the computer will draw a graph of conversational fluency as a function of time, and also will display:

• amount of conversation time (sec) that contained breakdown/repair
• per cent of conversation time that contained breakdown/repair
• number of breakdown/repair events
• average time (sec) per breakdown/repair event