Audio Devices

Audio plays a crucial part in any video conferencing experience. It’s possible to hold a successful conference with less than ideal video quality.  However, the same can not be said about audio.  Sound quality must be high or communication will suffer.

There must be no feedback path between audio-in (a microphone) and audio-out (a speaker or headphones). That is, the audio in and out components must be separated or feedback will result in an annoying echo or auditory disturbance.

The range of human speech should be covered by both the audio-in and audio-out hardware (8kHz or less). Most of the power in the human voice is found up to 4kHz, with higher frequencies providing extra definition and intelligibility.

Separation can be achieved by:

• An individual headset with integrated microphone and headphones
• Use of echo-cancelling hardware/software that simultaneously allows a microphone for room audio pick up while participants are listening to remote participants via speaker.

It’s also important that ambient noise is not transmitted to other sites and that room acoustics should not adversely affect audio transmission and reception quality. Whether one-on-one or in a group, audio hardware and software should be “invisible” to meeting participants – making conversation as comfortable as talking in person.

What not to do (generally speaking...)!

One of the potentially worst possible combinations is a stand-alone microphone close to one, or a pair, of desktop computer speakers (or, similarly, an inbuilt mic with inbuilt speakers). This can be a recipe for audio feedback, and when feedback is severe enough, it can ruin the meeting for all involved (and usually the person whose hardware is producing the echo will not be able to hear it...). EVO can attempt to reduce such echo via its own inbuilt echo-cancelling facility- but in general it is much better to avoid such an invitation to feedback in the first place- the device types listed below are what you should be aiming for, as much as possible.

In practice, it has been found that various combinations of inbuilt mics and speakers- and also stand-alone devices- can be used successfully with EVO. Their use does not always result in debilitating audio feedback- but it is more likely to occur when using such, as compared with using the type of devices listed below. It always pays to test one's audio quality with someone else at another location when trying new hardware- it may be that your particular mic/speaker setup is OK, or it may produce unacceptable levels of feedback.

That said, some webcams now offer inbuilt echo-cancelling, and may provide sufficient quality to be used as the room mic, with room speakers. Of course, experimentation and testing is required when setting-up any such hardware.

Suitable hardware

1. Headset – This is the easiest solution for individual use – simple, cheap and without an echo. Depending on the price and quality, headsets are capable of producing very clear audio with minimal feedback. Some headsets are USB devices, whilst others are analogue with separate in/out jacks (which will not be compatible with some Macs). Be prepared to purchase a good-quality item- various Sennheiser and Logitech sets starting around the AUS$50-$60 mark have been found to be most usable.

2. Integrated echo-cancelling microphone/speaker unit – These self-contained units incorporate one or more microphones and a speaker. They can have very good sound quality, are simple and comfortable to use, can accommodate several participants and are reasonably priced. They allow users to converse in a natural way, and enable more than one person in the same location to participate in a conversation. There are a number of these types of devices.  Examples include the Clear One Chat 50 and the Clear One Chat 150 USB (pictured); similar devices are also made by Phoenix (see the "Products" link at http://www.phnxaudio.com/).

3. Echo-cancelling microphone – In this solution, the microphone and speaker systems are separate – but the microphone has a built-in echo-cancelling capability. The microphone is used for audio input and an external amp/speaker system is connected for audio output. An example is the Clear One AccuMic (pictured). The system is relatively easy to use, suitable for groups up to 12 and independent of (bit does require) a sound reproduction system for listening to incoming audio from remote sites.

4. Combined hardware/software multi-input system – These devices allow for multiple audio input sources. They are versatile, can combine various audio sources, have refined echo-cancelling and noise reduction capabilities, enhance overall sound quality throughout a room and can be used in larger venues while effectively maintaining two-way audio. It allows multiple microphones to be placed around a room, and can patch in other audio sources as required. For larger venues, these systems are required. A good example of this type of solution is the Clear One Converge Pro 880 (pictured).

The items listed above have been used by ARCS customers. Their listing is not to be interpreted as an endorsement or a suggestion that these are the only options able to be used.