Maintenance Manual

Recordings
Call Events Administration
159
Improving Detection of Silence and Talkover Events
The adaptive Voice Activity Detector (VAD) algorithm uses is very robust and accurate
under normal phone call situations. In this case, normal means:
• Minimal to no background noise for both parties on a call.
• Good audio quality.
• One party for each side of a call.
• Each party speaks at normal volume.
The adaptive VAD algorithm has been proven to be 90% accurate through testing under
moderately noisy conditions. It can handle background noise (for example, white noise)
quite well. Rapid changes in volume and frequency of any background noise can cause
inaccuracies as the algorithm adapts to the noise. A constantly changing background
noise (for example, a radio playing loudly) will prevent the adaptive VAD algorithm from
working, and the results will be inaccurate.
Set minimum threshold values for silence and talkover events that are meaningful to
your call center. The threshold values define the granularity of the searches you can
run on recorded calls. For example, if you set the minimum duration for a Save Talkover
Event to 10 seconds, the user cannot search for recordings with any talkover events of
5 seconds or less because Quality Management only saves talkover events that are 10
seconds or greater. If your users requires greater granularity when searching for a
silence or talkover event, then lower the value for the minimum duration of the event.
If your call center does not fit the definition of normal given above (for example, there
is a lot of background noise), it might be better to use shorter minimum durations for
silence events to account for the noise interfering with correctly identifying silence
Silence Event
Minimum
Duration
The minimum amount of time in seconds for a silence event. Quality
Management only saves information about silence events with a duration
that is equal to or greater than the number of seconds specified in this
field. You can specify from 1 to 3600 seconds (1 hour). The default is 10
seconds.
This threshold setting is used during after-call processing and applies to
all calls. If you change this setting, all previously processed calls use the
older threshold settings.
Using a low threshold (for example, 3 seconds) stores more information
about events than a high threshold (for example, 30 seconds). If you
specify a 30 second threshold, a user cannot search for recordings with
silence events that are under 30 seconds. Quality Management does not
save information about silence events below the specified minimum
duration.
Field Description