Understanding Telephone Echo

Today’s users have very high expectations regarding the quality of phone calls, and there are many issues that can occur with a voice connection, including echo. Businesses depend on clear communication channels in their customer interactions and more and more are taking a truly proactive approach to audio quality management. 

One of the most common, and most irritating, problems which you can face in a call is echo. Echo is the phenomenon wherein speakers hear their own voice echoed back after a brief delay.  Although some technologies alleviate many causes, echo is still a constant issue even with the widespread availability of VoIP. 

A notorious cause of customer complaints and churn, constant echo coming from both your agents and customers ends makes it a struggle to understand what is being said, which results in a dropped call. Similarly, when a conference call suffers from audio issues, including echo, background noise, poor volume, or static, the brain has to work harder to focus on the most important source of the sound. Organizations actively want to avoid these situations as it lowers employee productivity and increases frustrations.

Sidetone is a unique kind of echo where sound effectively loops back between the speaker and microphone at one end of a phone call, as a form of electrical feedback through the telephone hybrid. While every telephone call has some echo, the concern is whether the echo is noticeable to the callers.


Causes of Echo

Echo can be caused by two or more call participants being located in the same room, but on individual equipment, with the audio cross-contaminating microphone inputs. It can also be caused by network issues, cabling, equipment configurations, or even a single user’s own speaker feeding back into his/her microphone. Echo, overlapping noises, i.e. talking over each other,' slow calls,' interrupted calls, and disturbed voice and video synchronization are all common effects of poor latency during conferencing.

Research indicates that when there is a delay of 35ms or less in one-way transmission (round-trip delay of <70ms), the speaker cannot distinguish the echo from an acceptable level of sidetone. However, as one-way delay increases beyond 35ms, the echo grows more problematic. The longer the delay, the more dramatic and invasive the echo becomes.


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Echo Reduction

To maintain speech quality, echo reduction and echo cancellation techniques are used in telecommunications networks and network infrastructure. These work to avoid or delete the echo once sensed from being produced.

Most network infrastructure in the route of any two callers will have configurations that will help control and mitigate echo, but most phone calls require several networks, and teams making distinct configuration decisions can manage each network. Echo remains a process which is ever-present.

Thankfully Spearline’s proactive monitoring and testing tools are able to identify these issues before your customer does, preventing your company from facing negative outcomes like customer churn and potential loss in revenue. The Spearline tests will determine precisely what the problem is, helping you to fix the issue promptly before it becomes too large an obstacle for you and your customers. Using an internationally-recognized standard for measuring audio quality, Spearline takes into account parameters like variable delays, noise on the line, and clipping of audio. You can read more about our test types here. 

To find out more about our latency tests and how to set them up in your organization, please download our latency fact sheet.


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If you are new to Spearline and would like to find out more about how you can benefit from our platform, we would love to speak with you. Please send us a brief message, and we will be in contact with you shortly.

About Us

Spearline is a technology company that proactively tests toll and toll-free numbers for connectivity and audio quality globally. It enables organizations to provide uninterrupted services to customers around the world. For further information, or if you have any further .

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