User Guide

9
Plantronics Acoustic Safety White Paper
Draft #4
Plantronics Acoustic Safety
White Paper
©2017 Plantronics, Inc. All rights reserved. 2.17 6826
One example of Plantronics headsets protected with SoundGuard technology is EncorePro HW720,
shown at left. For the full list of Plantronics headsets featuring SoundGuard technology, see the
product sheet at the end of this paper.
SoundGuard Plus features multistage limiting technology. A Peak Limiter clips high unwanted
impulsive signals, such as pops and clicks, as well as long-duration disturbance with a virtually
instantaneous attack time of less than one millionth of a second. The clipping level varies from
product to product due to the variation of the sensitivity of the headset driver. However, in all
Plantronics headset products with SoundGuard Plus technology, the highest clip level ever
measured is 106 dBSPL, which is much lower than the 140 dBSPL impulse and 118 dBA
long-duration disturbance limit set by regulatory and industry standards.
If the incoming loud signal continues, a Linear Limiter further reduces the system gain to maintain
a linear signal that is approximately 6 dB below (twice as quiet) the instantaneous clip level within
a few milliseconds. If the incoming loud signal still persists, a Dynamic Level Adjust algorithm will
continue to drop the signal level to 22 dB below the clipped level in less than 350 milliseconds.
Below is a comparison with SoundGuard Plus vs without SoundGuard Plus technology on a very
loud signal in normal speech. The output shows that without SoundGuard Plus, the loud noise is
clipped by SoundGuard technology to below 115 dB. With SoundGuard Plus, the loud signal is first
clipped by the Peak Limiter algorithm to about 106 dBSPL instantaneously. When the loud signal
continues, the Linear Limiter algorithm cuts the noise to 100 dBSPL in about 10 milliseconds.
When the loud signal still continuous, the Dynamic Level Adjust algorithm further attenuates
the noise level to about 87 dBSPL.
Simply put, SoundGuard Plus is an adaptive technology that quickly attenuates the loud
noise while allowing the natural voice to remain unchanged, thus ensuring continuous clarity
of communication.
EncorePro HW720