Device-related issues can affect voice quality before the audio
signal is encoded for transmission on the network, or after the
audio signal is received and decoded for playback on the client
speakers. Product defects or configuration errors in computer
hardware, peripherals, operating systems, drivers, enhancement
software (for example, additional audio programs or features that
are provided by device manufacturers or other vendors) can affect
Enterprise Voice quality if they interfere with the audio
processing algorithms of Office Communicator or Live Meeting
clients. Environmental issues (for example, device placement) can
affect Office Communicator, Live Meeting, and USB telephones.
Serverprovides device details in call quality reports, which
can be useful for tracking trends on a specific device version with
|The Optimized for Microsoft Office Communicator logo identifies
phones and other devices that are optimized for Office Communicator
2007 R2 and Office Communications Server 2007 R2. For details, see
Phones and Devices Optimized for Microsoft Office
Communicatorat Microsoft TechNet at
The following table describes hardware and software-related
voice quality issues.
Table 1. Hardware and
software-related voice quality issues
||Potential Symptoms and Causes
- Echo due to poor speaker or microphone isolation, which can
cause acoustic feedback. For example, a laptop computer that has
the microphone and speaker located close to each other could have a
problem with echo that is related to acoustic feedback.
- Low-fidelity audio input or output that is caused by a
microphone or speakers with insufficient frequency response.
- Extra latency introduced by the digital signal processor (DSP)
on the device.
- Half-duplex (one way at a time) conversations that is caused by
a built-in acoustic echo canceller (AEC) on the device.
- Audio cutouts that are caused by low signal-to-noise ratio on
- Low volume because the person who is speaking is too far from
- Low volume because of obstructions between the microphone and
the person who is speaking.
- Clipping that is caused by the microphone being too close to
the person who is speaking or because the person is speaking too
- Echo related to acoustic feedback because the microphone is too
close to the speakers, as in a small enclosed space, such as a
- Intrusive background noise because the microphone is too close
to a noise source such as a computer fan or hard drive.
- Audible breathing sound because the person speaking is too
close to the microphone.
- Acoustic feedback that is caused by multiple participants being
close enough to each other that their microphones pick each other
Excessive static noise
- Faulty device or device driver that corrupts the audio stream
at its source.
Hidden volume settings
- Main volume, microphone volume, and physical volume knobs on
headsets, as well as microphone boost settings and device driver
gain settings that can affect volume (and may not be obvious).
Incorrect device selection
- Plugging and unplugging devices, which can cause the latest
device to be used instead of a previously selected device (contrary
to the user expectation).
- Terminal servers or remote desktop sessions, which can change
- Multiple devices of the same type that have similar names.
- Use of unmatched microphone and speaker devices, which can
cause unexpected results (especially if a microphone and speaker
are designed to be used with each other, but the client computer
does not use them together).
- Extraneous noise caused by the microphone not being well
isolated from the speakers.
- Speaker volume is too low for hands-free use.
- Degraded voice quality caused by running the computer in
Use of extra audio enhancement software
- Separate audio enhancement software, which can interfere with
audio processing in Office Communicator 2007.
Low computer processing power
- Impaired audio processing caused by running too many programs
at once or by using a computer that does not meet the minimum
requirements for Office Communicator 2007.