Exam 2 Flashcards
What are the visual modes of communication?
Speech reading and Manual Communication
What used to some extent by the majority of the HI population?
Speech Reading
What is the most important component of speech reading?
Lip reading
Which components of speech reading provide considerable information?
Facial expressions, posture, context, and gestures
What is context in regards to speech reading?
The setting, topic, and linguistic context (utterances)
Which two factors influence the visual perception of speech?
Visibility of speech sounds and homophemes
How does the visibility of the articulators influence the visual perception of speech?
Sounds that are produced near the front of the mouth are more visible than those produced in the back
Which speech sounds are the most visible?
P, B, M, F, V, O
Which speech sounds are least visible?
K, G, H, Y
What is a homopheme?
Phonemes or sounds that look alike
What is a viseme?
A group of sounds which look alike (p, b, m)
What percentage of English consonants are homophenous in nature?
Approximately 50%
How does rapidity of speech affect speech reading?
Extremely slow speech distorts speech reading, a moderate rate with frequent pauses is helpful
What should you avoid in order to increase intelligibility for a speech reader?
Avoid extraneous gestures (hand in front of mouth, gum chewing)
How are lip reading skills assessed?
There is no acceptable test or battery due to a lack of validation. Tests are available but informal.
What two categories do traditional lip reading training methods fall into?
Analytic methods (Bruhn, Brauckmann, Bunger), and Synthetic methods
What is the analytic method of lip reading training?
One which focuses on the phonemic level (segments) before larger constituents
What is the synthetic method of lip reading training?
One which focuses on whole utterance recognition
Is lip reading a major form of aural rehab?
No, little is known on how skills are developed, and there is little evidence to document the benefits.
What is the current priority in aural rehab in regards to training?
To work on integration of auditory and visual cues
Who uses manual communication?
Severe to profound population
History of sign: Italy 1500s
Geronimo Cardano - physician who taught his deaf son
History of sign: Spain 1500s
Benedictine monk Pedro Ponce De Leon educated deaf children of Spanish aristocracy - developed early system
History of sign: Spain 17th century
Pries Juan Pablo Bonet published “Reduction of Letters and Art for Teaching Mute People to Speak”
History of sign: France 18th century
Abbee Charles-Michel de l’Epee alphabet based on Bonet’s. “Father of Sign Language”
What are the origins of ASL?
Originated early 19th century in the American School for the Deaf. Founded by Thomas Hopkins Gallaudet in 1817.
What is ASL most closely related to?
French sign language
Which forms of sign language are mutually intelligible?
ASL, British SL, and Australian SL.
Where is ASL used?
N. America, parts of Africa, SE Asia, and S. America.
What are the two sign types?
Finger spelling, sign systems
What are the features of finger spelling?
Relatively easy to produce but difficult to read, mainly used as an adjunct to sign
Which three elements contribute meaning in ASL?
Shape of hand or hands, position of hand, movement that is executed
What is an iconic symbol?
One that can be recognized by anyone because it looks like the thing it stands for.
What is a non-iconic sign?
One that does not resemble it’s referent.
What does it mean to say that human languages are strongly non-iconic?
They use arbitrary signals.
Why is ASL a true language?
Because it has non-iconic signs and it is generative
ASL has it’s own _______ and ________.
grammatical structure and vocabulary
What do ASL signs represent?
Concepts
Do all ASL signs have English equivalents?
No
What are there no signs for in ASL?
Pronouns, articles, or function words
Around how many signs are there in ASL?
6000
How many people use ASL?
500,000 to 2 million
What does analog refer to?
The natural world
What does digital refer to?
The artificial
What is a pure tone?
Simple sine wave/energy at a single frequency
Which signals are continuous in time and amplitude?
Analog
Which signals are discontinuous in time and amplitude?
Digital
What is an ADC?
Analog to digital converter - used to convert analog signals to digital ones
What has discrete values that represent points along a continuous curve?
The time and amplitude of a digital signal
What are the benefits of DSP?
Miniaturization and because there are many more signal processing options
Why is miniaturization beneficial when it comes to hearing aids?
Allows for a very small chip instead of wires and transistors, and allows for easy controls for wearer and for audiologist making adjustments
Prior to digitization, how were hearing aid controls adjusted?
With a screwdriver
What remains an issue with hearing aids?
Ambient noise
What are the parts of a hearing aid?
Microphone, signal processor, receiver, battery, and earmold
Which part of the microphone changes energy from one form to another?
the transducer
What are the components of the signal processor?
The amplifier, filters, output-limiting circuits, and feedback limiting circuits
What increases signal voltage by an amount determined by the gain control?
the amplifier
What is the transducer that converts electrical signal to acoustic energy?
The receiver
Why is the earmold always custom made?
Because it must fit snuggly to reduce feedback
What is feedback?
Squealing or whistling sound produced when the output of the aid is picked up by the mic and reamplified - happens many times per second
When does feedback occur?
When the earmold is loose and allows amplified sound to leak out of the ear canal
What are the user controls on a hearing aid?
Volume control (Sometimes absent), on-off switch (sometimes just have to open battery), telephone switch
What is a T-coil?
A component of a hearing aid that detects speech signals via electromagnetic waves (EMW)
What does the mic on a hearing aid detect?
The speakers voice and the ambient noise around the listener.
What does the T-coil detect?
Only the speakers voice, music, etc.
Why can’t a T-coil detect ambient noise?
Because ambient noise is an acoustic signal, and t-coils only detect electromagnetic waves
What does T-coil reception maximize?
Signal to noise ratio
What is the signal to noise ratio?
The ratio of the signal to the ambient noise in a listener’s background
What should the S/N ratio be for the hearing impaired?
At least 12 dB
How are the internal controls set on a hearing aid?
By an audiologist using a computer program
What are the hearing aid tone controls for?
Matching the frequency response of the aid to the users hearing loss
In what frequencies does ambient noise tend to be?
The lower frequencies
What type of filters do tone controls tend to be?
High-pass filters
What two factors are important in regards to output limiting controls?
- Even a moderate hearing loss may require considerable gain
- Most people with a SN hearing loss exhibit some degree of recruitment
What is recruitment?
An abnormally rapid growth of loudness
What is the purpose of a compression circuit?
To reduce the amount of gain as the output signal becomes more intense
What is an air conduction aid?
A hearing aid which is coupled to ear canal, amplified sound delivered acoustically to the ear drum
What is a bone conduction aid?
An external BTE unit amplifies and transmits vibrations to a screw, bone conduction of vibration to inner ear fluid
What is a bone conduction aid used for?
Conductive hearing loss, atresia, unilateral losses, or chronic otitis media
What is a middle ear implant?
An electromagnetic (or other transducer) is affixed to the TM or one of the ossicles an dis driven by an external device
What are middle ear implants used for?
SN or conductive losses
What are the advantages of middle ear implants?
Very efficient, minimize feedback
What are the disadvantages of middle ear implants?
They are extremely invasive
What is a brainstem implant?
An electrode array that stimulates the cochlear nucleus and is wired to a body-worn processor
When is a brainstem implant used?
When VIII is missing or damaged
The higher the S/N ratio, the more ______ the listening environment.
Favorable
What SN ratio is considered unfavorable for listening with amplification?
Less than 10 dB
What is the ideal S/N ratio?
+12 dB
What is the S/N ratio of a typical classroom?
0 to +6 dB
What is the typical ambient noise level for a classroom and hotel meeting room?
63 dBa, 58 dBa
What is the desirable ambient noise level for a classroom and hotel meeting room?
35 dBa, 45 dBa
What are the two major problems with environmental acoustics for hearing aid users?
Signal to noise ratio and reverberation
What is the optimal reverb time?
less than 0.5 seconds
What is the typical reverb time?
avg up to 1.5 seconds
What three factors minimize ambient noise and reverb in a room?
- Use of sound absorbing materials
- Seating the child away from noise systems
- Sealing windows and doors to minimize outside noises
What is the best solution for S/N problems?
The listener uses an FM device
What S/N ratio is possible with an FM device?
+15 dBa
What is the FDA age requirement for cochlear implants?
12 mos, though some center do it younger
What is the hearing loss level required for cochlear implants?
Profound
What do you need to establish when considering cochlear implants for adults?
That performance with implants will be better than performance with hearing aids
What is the avg SDT for implant patients?
24-40 dB HL
What score do most adult implant users score on open set sentences in speech recognition testing?
70-80 %
What score do most adult implant users score on monosyllables in speech recognition testing?
30 - 40%
Does cochlear ossification preclude implantation?
No, but it may determine depth
How long does the cochlear implant surgical procedure take?
2-5 hours
What is recruitment?
The abnormal rapid growth of loudness
