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23 Cards in this Set
- Front
- Back
reasons to use compression |
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What is compression for high level sounds? |
high gain for high level sounds |
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POOR COMPRESSION CAN ALTER TEMPORAL ENVELOPE OF SPEECH SIGNAL |
memorize that |
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effects of compression |
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choices of compression speed |
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automatic volume control |
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compression alters the envelope
fast acting compression has more dramatic effect in temporal envelope |
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major advantages of AVC |
less distortion of the temporal envelope of speech |
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major disadvantage of AVC |
may render speech signal following compression inaudible due to longer release time |
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syllabic compression |
fast acting compression that attempts to compress at the syllabic level (fast attack and release times) |
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When does syllabic compression attempt to compress and release? |
before next portion of speech signal |
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advantages of fast acting compression |
applies compression and release quickly to allow listener opportunity to perceive following phoneme
attempts to compress at the syllabic level
better for utilizing TFS of speech for dip listening |
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disadvantages of fast acting multi-channel compression |
distorts the temporal envelope
unknown what the optimal number of channels should be
bor, souza found reduced vowel identification with multichannel compression |
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bor, souza, and wright took vowel signals, processed then through different compression mechanisms and found what? |
in uncompressed, you could see spectral contrasts
as compression increased, spectral contrast decreased as well as vowel identification |
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dip listening |
the ability to utilize the information in fluctuating background noise |
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dip listening and temporal fine structure |
allows the listener to define properties of target speech |
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cochlear hearing loss of a moderate degree can (reduce/increase) ability to listen in dips |
reduce |
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What type of compression system would be most beneficial for dip listening and why? |
AVC because it is fast acting |
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What determines the type of compression that would be most effective? |
the hearing impaired listener's ability to use TFS |
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compression for severe-to-profound SNHL |
traditionally, individuals with this HL were typically fit with linear, output limiting instruments
listeners became accustomed to reduced bandwidth signals, increased amplified noise, and more distortion with output limiting devices
souza suggests that amplitude compression needs to preserve, as much as possible, the natural amplitude variations in speech (temporal envelope) |
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3 has the highest EDI (envelope difference index) |
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What can you do due to the gain for soft sounds (including environmental sounds) with WDRC |
counsel, expansion |
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expansion |
reduces gain as input decreases, below the TK |