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.

Monitoring Serverprovides device details in call quality reports, which can be useful for tracking trends on a specific device version with known issues.

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

Issue Potential Symptoms and Causes

Device design

  • 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 the microphone.

Device placement

  • Low volume because the person who is speaking is too far from the microphone.

  • 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 loudly.

  • Echo related to acoustic feedback because the microphone is too close to the speakers, as in a small enclosed space, such as a office cubicle.

  • 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 up.

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 preferred devices.

  • 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).

Laptop use

  • 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 power-saving mode.

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.

See Also