If you are using web conferencing software in your face to face classroom and you want to have it work successfully with remote students, there are some important things you need to know about microphones. Experience has shown that simply trying to use the built-in or external microphone that comes with your computer DOES NOT WORK WELL. Often you or your students are too far from the computer for the computer microphone to pick up any audio, or the audio quality of the external computer microphone is very poor. If you are teaching using one of the media carts provided by eMAP, or in a multimedia-console equipped classroom, you can often arrange AHEAD OF TIME with eMAP to have other microphones provided, or to have them show you how the console microphone system works. If you are using your own computer in a regular classroom, you may need to make other arrangements, either to borrow a reasonable microphone, or purchase one.
The answer to this depends (not surprisingly) on what you are doing:
1. Virtual Office Hours
If you are using web conferencing or Skype for providing online office hours (where you are generally working/meeting with only one student at a time) you can often use a built-in microphone (should your computer be so equipped) and a set of headphones... However, if you don't have a built-in microphone, you might as well purchase a USB headset to do this as well.
Another option that IS available out there are webcams with built-in microphones. These would be best suited for using with Skype or for one-on-one/small group interaction through web conferencing, although depending on the cost of the webcam, the quality of microphone varies. They are also sensitive about their placement (eg, placing them on top of your computer tower so they pick up your video best often means that the microphone picks up the hum of the computer fan).
2. Teaching in a distributed classroom/Teaching to Remote students
Usually if you are using web conferencing for teaching in a distributed classroom, you only need a headset, as you are for the most part going to be using your own computer, and have no "studio audience" physically in your room with you. USB headsets generally cost between $35 and $150 and are available from the Campus Computer Store and many other vendors.
3. Blended (Local and Remote) Instruction
If you have students in your physical classroom and students accessing remotely, the type of microphone(s) you will need will depend on how large your classroom is. If you are teaching in a small room (4-10 people, sitting in close proximity to you), you may be able to use a USB microphone like the Yeti microphone from Blue Microphones
Also VERY useful but somewhat more expensive is the ClearOne Chat 150 conferencing microphone
If you have a larger, lecture-style room where you are teaching from the front and have students seated in rows in front of you, you're going to need a minimum of two microphones (preferably wireless), one for yourself (usually a lapel-type microphone) and one for your "in house audience" so that your remote students are able to hear your local students. Usually this second mic can be a hand-held microphone like reporters use (it can be passed from student to student, and turned on and off as needed), in some cases a "room microphone" can be used (although those can't generally be turned off when not in use so tend to pick up other distracting room noises during your instruction). Having TWO microphones generally makes things somewhat more complicated, and certainly adds to the expense. eMAP's Equipment Service group has SOME wireless microphones that can be booked in advance for loan on an occasional basis, while the Web Conferencing Support team within ICT two sets of wireless microphones that we can loan for demonstration and testing purposes.
4. Mixed Seminar (Local and Remote Audiences)
If you are offering a mixed seminar, where you have a local audience in the room and remote participants joining via web conferencing, you will GENERALLY need the same two-microphone setup that you need for working in a larger classroom. However, if you are NOT interested in eliciting feedback from your locau audience, you MAY be able to use the "house" microphone that many larger lecture theatres are now equipped with. These generally have a wireless lapel microphone stashed somewhere around the multimedia console within the room, and MANY of these consoles are now able to transmit that audio out through the computer via web conferencing applications. However, before making that sort of decision, you should check your specific room to ensure that it is technically capable of that.
5. Distributing Conference Proceedings by Webinar
This is a special case, but should be noted as it is growing in importance. "Webinar-ing" conference proceedings is becoming far more common these days, and there are some important considerations about providing microphones for this type of situation. In many cases where a conference is filling a large venue, there will be a "house" sound system brought in or available within the room to amplify the audio for both the presenter and the audience members (usually a microphone on a stand for participants to ask questions). During the planning stages of the conference, if you consult with the group who is providing the A/V hardware for your conference, they can generally arrange to provide you with an audio "feed" that you can connect to your web-conferencing computer. Usually what you would need to tell them is you want an "1/8" Sony plug audio feed", that is, a plug the size of your microphone input on your laptop.
Here is just a SMATTERING of geeky information about the different TYPES of microphones available, and what effect they have on your use of them for web conferencing.
Electret-Condenser microphones - This type of microphone is usually used for either lapel microphones or computer mics. These have a very narrow sound pickup pattern, so you MUST have them fairly close to your mouth for them to work well... Downside is, they don't work for picking up people speaking at a distance (ie, further than a foot away). Upside is, they don't pick up much background noise so they give good clean sound for a presenter.
Dynamic Microphones - This is the type of microphone usually used in handheld microphones, wireless or non-wireless. They have a wider sound pickup pattern, so they work well for interview-type situations where the mic is between two people and not necessarily very close to their mouths. Upside, better sound for small groups. Downside, they pick up more background noise.
PZM (Pressure Zone Microphones) - This type of microphone is a little more rare, but can sometimes be found in larger lecture theatres. It is usually a flat, square microphone, (often looks like a squashed brick, ) and it usually sits on the table in front of you or is hung from panels in the ceiling. The theory behind this microphone is that you place it on a flat surface and it picks up the audio "vibrations" reflecting off that surface (it turns that surface into a big micrphone). This type of microphone has a very wide audio pickup pattern, so it works well for picking up student responses to questions in a lecture theatre.... HOWEVER, this wide pickup pattern also means that they can pick up A LOT of room noise, making people sound like they are talking in a barrel if they are some distance from the mic. So generally, when this type of microphone is used in a production environment (like a TV studio), you only turn it on/turn it up when you really need it. This is a bit of a problem for web conferencing as you do not often have a technician who can manage your microphones like that.