When the USB port is used for sound, the sound must be transmitted
through the port in the form of digital data. This digital audio stream
can be modified and enhanced directly from the PC. This is a major
area where Plantronics digital headsets differentiate themselves.
All Plantronics digitally enhanced headsets have in-line modules
that utilize three separate chipsets to provide the best audio with
our speakers and microphones:
A streaming controller pulls the audio
information from the USB bus and puts it back again
A 24 bit high signal to noise CODEC that
takes audio data and converts it from an analog stream to digital
one, and vice-versa
A 32 bit dedicated audio Digital Signal
Processor, to modify the signal
The use of the DSP is what makes the Plantronics headset line truly
digitally enhanced and unique. The DSP and circuitry in the In-line
Control can enhance and customize the signal in a number of ways.
For example, in the case of a speech recognition application, the
DSP can be used to improve the signal-to-noise ratio (also known
as signal level compensation) of incoming speech, resulting in greater
recognition accuracy.
In fact, Plantronics has done testing which indicates that using
a USB-based, digitally modified signal significantly improves accuracy
in speech recognition applications, particularly in environments
with a lot of ambient noise (see graphic).
In much the same way that a stereo equalizer can be adjusted to
optimize audio quality for a particular type of music or sound (i.e.
movies), the DSP can also apply appropriate filters to the audio
stream depending on the type of application being run. Therefore,
whether you're running a speech recognition application, playing
an MP3 or a CD, chatting over the Internet, watching a movie, or
playing an action game, you'll always have the audio parameters
set appropriately for optimal performance.
Using the PC Audio Control Center software, which comes with the
headset and is exclusive to Plantronics, you can adjust numerous
audio settings as well as apply various effects. Furthermore, once
selected these presets are stored in non-volatile RAM within the
headset, so you can move it among PCs without losing your settings.
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Plantronics
digital headsets also provide in-line, push-button volume level and
mute controls (see graphic). These digital volume controls provide
greater precision than analog wheels. Volume settings are also saved
within the headset's memory.