11 Mar 2015

Problem:

There is a long silence between the time a voice broadcast call is answered and the time the message begins playing.

This is an age-old problem, detrimental to the quality of your broadcast and likely the receptiveness of your recipient toward the call. Of course, we want to reduce this silence as much as possible to give the listener the best experience.

Background:

In another article, we discuss how to determine whether a call is answered by a human or by a voicemail system by analyzing the initial greeting of the recipient. Gigabark also determines when the initial greeting has ended, so it can determine when to start playing the message.

One solution to this silence problem is to simply start the message as soon as the call is answered. However, this may not increase the recipient’s experience, and may actually decrease it. The message may play over the recipient’s greeting, or the message might be severely clipped by a voicemail greeting or the time it takes the listener to place the receiver to their ear.

But how does the analyzer know when the initial greeting is over? Of course, as long as there is voice activity coming from the recipient, the analyzer thinks the greeting is not yet over. At some point, the greeting will end, but the analyzer continues to listen for a short period of time for more voice activity before declaring the greeting ended. So some delay prior to beginning the playing of the voice message will always occur, but it is generally very small (less than one second, but typically less than half of a second).

Causes for Silence:

The following may be reasons for silence prior to the start of the message:

• The analysis of the initial greeting (discussed above)
• NO initial greeting is given. For example, when testing a broadcast you might not say “Hello” since you expect a recording. This throws off the analyzer, which assumes a voicemail system answered and waits longer.
• Silence in the message itself.
• Background noise on the recipient’s end may be the biggest cause. If the analyzer thinks that background noise is part of the recipient’s greeting, it will continue analyzing until there is silence. It will not start playing the voice message until it believes the initial greeting is complete.
• Particularly in messages left on voicemail, there is more delay in the analysis of the greeting due to the wide variety of voicemail systems. Since some systems play a tone to signal recording and some don’t, it isn’t sufficient to analyze for the tone, but for the end of voice activity. To make matters worse, since the systems may wait up to 3 seconds after the mailbox greeting to play the tone, we must analyze for much longer to verify the end of the voice activity prior to playing our voice message. We do all of this work to prevent playing the message prior to the time the voicemail system starts recording. It is also worth noting here that some voicemail systems listen for too much silence at the beginning of voicemail messages and may discard the voicemail messages if it contains too much initial silence. This may explain why a voicemail message may not be deposited at all.