填空题
{{B}}Directions:{{/B}} Read the following text and choose the
best answer from the right column to complete each of the unfinished statements
in the left column. There are two extra choices in, the right column. Mark your
answers on theANSWER SHEET. The human
voice, like any sound produced by thrumming a stretched string, has a
fundamental frequency. For voice, the centre of that frequency lies mostly below
300Hz depending on the speaker's sex. Information is conveyed through
simultaneous higher-frequency overtones and additional components that can
stretch up to 20,000 Hz (20kHz). Modern hearing aids are able to distinguish
only a small part of that range, typically between 300Hz and 6kHz, reducing
noise and amplifying those frequencies where the wearer's hearing is
weakest. But differentiating elements of many common parts of
speech occur in higher frequencies. This is the result both of harmonics that
ripple out from the main tone, and from non-voiced elements used to utter
consonants, which employ the tongue, teeth, cheeks and lips. Take the words
"sailing" and "failing". Cut off the higher frequencies and the two are
indistinguishable. The problem is compounded on telephone calls, which do not
transmit frequencies below 300Hz or above 3.3kHz. People with
hearing aids experience this problem constantly, says Brian Moore of the
University of Cambridge. Typical hearing loss tends to be most acute at
frequencies above 10kHz, which contain quieter sounds but where speech can still
include important cues. Older hearing aids cut off at no higher than 6kHz, but
much modern equipment stretches this range to 8-10kHz. However, a problem
remains, Dr. Moore says, because bespoke hearing-aid calibrations for individual
users, called "fittings", do not properly boost the gain of these higher
frequencies. So Dr. Moore and his colleagues have come up with a better method.
Their approach can be applied to many existing devices, and is also being built
into some newer ones. A key step in any fitting involves
testing an individual's ability to hear sounds in different frequency bands.
Each hearing loss is unique, and for most users a standard profile would be too
loud in some ranges and too soft in others. But current tests pay scant
attention to the higher frequencies that a device's tiny speaker can produce,
regardless of whether the user needs a boost. Dr. Moore's new test, known as
CAM2, which is both a set of specifications and an implementation in software,
extends and modifies fittings to include frequencies as high as 10kHz. When the
results are used to calibrate a modem hearing aid, the result is greater
intelligibility of speech compared with existing alternatives. CAM2 also
improves the experience of listening to music, which makes greater use of higher
frequencies than speech does. A．be applied to many existing
devices B．use the tongue, teeth, cheeks and lips
C．enhance the gain of higher frequencies D．pays little
attention to the higher frequencies E．reduce noise and amplify
certain frequencies F．transmit frequencies below 300Hz or above
3.3kHz G．extends and modifies fittings to include high
frequencies
填空题
Modern hearing-aids can ______.
填空题
To speak consonants, we need to ______.
填空题
The telephone calls can not ______.
填空题
Bespoke hearing-aid calibrations do not ______.