Use troubleshooting methods to solve QoS issues
Questions derived from the 642-425 – IP Telephony Troubleshooting Exam Cisco Self-Test Software Practice Test.
Objective: Use appropriate troubleshooting methods to determine and solve QoS issues in complex IP Telephony networks
SubObjective: Identify common problems associated with voice echo
Item Number: 642-425.5.3.12
Multiple Answer, Multiple Choice
Which of the following statements are TRUE regarding listener echo? (Choose two.)
- The listener hears the talker’s voice twice.
- Listener echo is due to inadequate loss of echo signal.
- Listener echo is caused by an acoustic echo produced by the listener’s phone.
- Listener echo is generally caused by a device known as hybrid.
- Listener echo takes place when acoustic energy from a device such as a handset enters the microphone of the same device.
Answer:
A. The listener hears the talker’s voice twice.
B. Listener echo is due to inadequate loss of echo signal.
Tutorial:
In listener echo, the signal leaks through the near-end hybrid and comes back to the listener. The following statements are true regarding listener echo:
- The listener hears the talker’s voice twice.
- Listener echo is caused by inadequate loss of the echo signal.
The following are the causes of listener echo:
- Inadequate loss of the echo signal.
- Long echo tail.
- Inactive echo cancellers in the gateway nearby the near-end hybrid.
The option stating that listener echo is caused by acoustic echo produced by a listener’s phone is incorrect because this is a cause of talker echo.
The option stating that listener echo is generally caused by a device known as hybrid is incorrect because this is a cause of electrical echo, not listener echo.
The option stating that listener echo takes place when acoustic energy from a device such as a handset enters the microphone of the same device is incorrect because this is a cause of acoustic echo, not listener echo.
Reference:
http://cisco.com/en/US/tech/tk652/tk698/technologies_white_paper09186a00801545e4.shtml#echoed
