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Echo Cancellation, Art or Science? Part I

  • On November 18, 2016
Background First, let us apologize that this post is going to be a bit technical. Don’t worry we will try to keep it as simple as possible.  Echo cancellation, and more specifically Acoustic Echo Cancellation (AEC) is theoretically a very simple algorithm. The AEC algorithm receives a reference signal (i.e. the audio played to the […]
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Echo in VoIP and Altruism

  • On November 18, 2016
What is echo in telephony? In a nutshell, echo is the phenomena in which your voice is being played back to your speakers. Echo has been with us since the early days of telephony. In the past, when most people where using PSTN lines, echo was less disturbing due to the fact that the delay […]
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Echo cancellation is now available for PJSIP

  • On May 15, 2016
Background PJSIP is an is a free and open source multimedia communication library. One of the most important components that influence the audio quality in VoIP communication solutions is the existence of a good echo cancellation.  SoliCall’s acoustic echo cancellation software is a powerful echo cancellation technology that is also flexible to support and tune […]
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Isolating the audio in VoIP networks

  • On March 2, 2016
Background In this post we would like to share with you a rare phenomenon we have seen in few sites that once it appears, it can cause a head ache to the network administrator. As opposed to the old telephony networks that was based on dedicated physical cables per call, usually twisted pair, the cables […]
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VoIP on Android – volume control

  • On January 16, 2016
Background In our previous posts we covered few of the difficulties that Android VoIP developers are facing – for example the challenge in providing high quality echo cancellation. In addition to the echo cancellation, the variety of hardware platforms that are running Android also introduces a challenge in controlling the volume of the voice.  
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Echo in Public Address systems – additional considerations

  • On January 16, 2016
Background This post is a continuation to our previous post on  AEC and Public Address systems. This post elaborates on additional considerations that should be reviewed when implementing and tuning acoustic echo cancellation software in PA systems. After analyzing relevant case studies, out of many important considerations, we have selected the below ones.
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How can echo suppression badly impact call quality ?

  • On January 16, 2016
Background Can phones/soft-phones with built-in echo suppression badly impact the audio quality? Surprising as it may sound the answer is positive. In other words, when a call center, or any other organization, purchase phones with built-in echo suppression it is jeopardizing the overall call quality.  In order to analyze the reason for this phenomena we […]
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Echo Cancellation on Android and AudioRecord

  • On June 5, 2015
Background When developing a VoIP application, most implementations use AudioRecord as the foundation class for capturing audio from the microphone.  Can this class be used to cancel echo as well ?  
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Echo Cancellation and silence

  • On March 11, 2015
Background Following our previous post on synchronization, in this post we would like to cover a specific aspect of un-synchronized input which causes the speakers to play silence that is not monitored and therefore unknown to the AEC.
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Tips for Developing VoIP on Mobile Devices (Android,iOS,…)

  • On August 1, 2011
CPU Consumption One of the main problems in mobile devices is their limited CPU Power. As a result the delay in the audio signal is increased and from time to time portions of the audio signal might get lost. In order to resolve these problems, you need to verify that your VoIP application is optimized […]
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