Most business users are familiar with audio & video conferencing and have experienced both technologies in a variety of situations. But, many users forget that these technologies are only as good as the audio foundation. Audio quality can be impacted by the type of device used to participate in the calls (i.e. using hands-fee devices like speakerphones or cell phones versus using non-hands free devices like telephone handsets). Too often microphones are not properly placed to hear those talking and users attempt to use a variety of audio devices, including cell phones, to connect someone into a video call. Voice quality in a video conference is impacted by the acoustics of at least two rooms – the caller and the listener.
Audio, that is voice, is almost always deemed the most critical portion of any conference. Without audio, the meeting loses nearly all value. A variety of equipment might be involved to hold an audio conferencing call or add audio into a video call, including telephone handsets, speakerphones for use by small groups, installed audio systems, microphones, mixers, and controllers to initialize and manage the call speakers.
The quality of the voice transmission line is crucial to the success of an audio conference. A regular (analog) dial-up telephone line is often all that is needed to conduct a successful audio conference. But users should be wary of individuals calling into an audio or video call on their cell phone. Both the quality of the line they are on and their location (driving in a car with a noisy truck passing them, near construction sites, etc.) can negatively impact the overall quality of the call. While many people use their telephone systems for three-way conference calls, and sometimes to even link multiple sites, a multipoint conference, of more than three sites, often requires an audio or video bridge to link sites together. A number of telephone and bridging service companies offer multipoint audio, data and video conferencing services. Calls can be established through an operator or on a dial-up basis. Keep in mind the call is only as good as the audio foundation. A noisy, hands-free conferencing connection can negatively impact the entire call, whereas video can sometimes be forgiven when lacking certain quality.
Humans can tolerate visual interference – a grainy image, untrue colors, and jerky images. But, the audio must be high-quality in order for listeners to perceive the words. Decades of research have shown how specific types of signal degradation affect perception. This research has been used to produce telecommunications networks that are optimized for transmission of high quality human speech.
One study, conducted by TRI, had 100 participants view video and evaluate the quality of the image as they thought the bandwidth of the video was being altered. In reality, the bandwidth allotted to audio was changed. The participants perceived the video improving as the audio improved, even though no changes were made to the video quality.
Audio must be high quality in order for people to perceive the words. Speech can tolerate some clipping or the loss of an occasional syllable, but time lag is intolerable to listeners during conversation. When the range in the voice is muffled and speaker identity and intelligibility are affected, calls are no longer understandable. All these factors make audio quality an extremely important component of a video conference. Lowered speech intelligibility will inevitably obscure natural communication, take focus away from important aspects of the meeting, and cause fatigue.
The way audio is handled in a video call can also be an issue. The quality of speech transmitted over a local area network (LAN) or wide area network (WAN) can be impacted by the way audio packets are handled. Compression and decompression of audio is a standard part of a video conferencing system, and can be a source of reduction in audio quality. Complete loss of some audio packets during transmission over the pubic Internet may also occur. As a result, the audio signal may suffer in quality and delay. In some instances, to optimize audio in a video conference, a full duplex voice telephone circuit is used to carry the audio portion of the conference. The independent channel can also be helpful for troubleshooting if participants have difficulty with the LAN or collaboration applications during a meeting. As an alternative, a company can pay a service provider with Quality of Service (QoS) technologies like Multiprotocol Label Switching (MPLS) and Differentiated Services or DiffServ, which allow audio and video data to be transmitted with a guaranteed level of quality.
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