Chp 4 Flashcards
Hearing assistive technology system (HATS)``
- Listening, alerting, and/or signaling devices that facilitate a patients communication w/the environment or enhance their personal safety through the use of auditory, visual or tactile modalities
signal processing
involves manipulation of various parameters of a signal
algorithm
mathematical formula that provides step-by step rules to perform a specific function or task such as processing and amplifying an acoustic signal
microphone
picks up the acoustic signal from the ambient environment
- transducer that converts an audio signal into an electronic signal
amplifier
increases the intensity of sound
receiver
an instrument that converts electrical energy into acoustic energy as in a hearing aid
- term also refers to the component of an FM system worm by the listener to receive signal from the FM transmitter
battery
- Provide power for its operation
2 types of microphones
directional & omnidirectional
directional microphones
more sensitive to sound originating from in front of the user than to sound coming from behind the ear
omnidirectional microphones
sensitive to sound coming from all directions
automatic directional microphones (ADMs)
automatically switch b/t an omnidirectional and directional mode according to environmental conditions
gain
of an hearing aid is the difference in decibles w/t the input level of an acoustic signal and the output level
preamplifier stage
signals from the microphone is amplifies
signal processing stage
signal is manipulated to enhance or extract component information
Digital noise reduction (DNR)
processing designed to reduce gain in the low frequencies or specific frequency bands when noise is detected
output stage
process signal is boosted
maximum power output
maximum intensity level that a hearing aid can produce, sometimes called saturation sound pressure level
peak clipping
method of limiting aid output in which a constant or linear amount of gain is provided across a range of input levels until it reaches a saturation level at which time the amplifier begins to clip off the peaks of the signal
saturation level
the point at which an amplifier no longer provides an increase in output compares to input
compression
nonlinear form of amplifier gaon used to determine and limit output gain as a function of input gain