If you are recording a lecture for class, you are likely to record with a webcam or relatively cheap headphone/mic combo. That is fine until you find yourself recording frequently and are ready to step up your game. Or more likely, you are just tired of picking up your headphones and getting variable sound output because of differences in battery charge. If that is the case, then it is time to get serious about microphones!
If you need just a bit more rationalization to justify buying equipment, then consider that people will tolerate worst quality video images more than poor quality audio (http://www.thesunchronicle.com/video_class/importance-of-good-audio/article_b353e69c-9424-11e3-98e7-001a4bcf887a.html).
If you aren’t yet convinced to open your wallet, then think about the time you were ready to record only to find loud voices outside your office, or the lawn care team showing up outside your home office. A new microphone might be the ticket to being able to record regardless of background sound.
What would I buy: Dynamic or Condenser?
You can watch YouTube videos on microphones to pick out a great one, but you are more likely to suffer from analysis paralysis. Before you decide what to buy, you have to decide which type of microphone to buy. Your first choice is dynamic or condenser microphone. For the difference go to this Rode site: http://www.rode.com/blog/all/dynamic-vs-condenser-which-live-mic-is-right-for-you
You can never tell who is paid to promote a microphone so another clue for quality is to find out what your favorite YouTuber uses. Which microphone produces sound that feels like it is in the room with you? (e.g., http://www.rode.com/microphones/procaster.) You can also find websites that compare microphone sounds (http://www.rode.com/microphones/procaster).
At the time I was looking there were two highly promoted options, the Rode Podcaster and the Blue Yeti. The former is dynamic, the latter a condenser microphone with some very cool features.
If you are ever tempted to have a conversational podcast with one microphone, then the Blue Yeti may be for you. On most occasions for educational videos, however, this condenser microphone is going to require some audio processing because it will pick up background noise. Some people work around this by building miniature sound isolation boxes (https://www.youtube.com/watch?v=UTeUeRxAS7M). The procaster or podcaster has the advantage of being a dynamic microphone that picks up only sounds close to the microphone. While you can avoid some basic audio processing, keep in mind it won’t work well as a microphone with a teleprompter. It will likely be in view of the camera frame.
Rode podcaster and procaster are dynamic microphones (http://www.rode.com/microphones/procaster) that avoid the need to reduce noise after recording. Instead I can record directly in Camtasia and the sound is clean (no lawn mowers in the background!) The procaster is a beast at 1.6 lb and 8 inches long. You won’t be tempted to carry it around. If you need a portable microphone, consider other options.
If you need to process audio, consider taking Paul St. Denis’s CELT workshop on Audacity
Audacity is free audio processing software. You can use it to reduce noise
Should you add music?
Save time and skip the music. If you must, then use it at the beginning and end. It is tempting when you use Camtasia, which has music files integrated. They provide easy intuitive options for fading and amplifying music.
You may be thinking, “it sounds so nice with music behind a voice!” Yes, but you may have to notch the frequencies of your voice out of the music track to allow your voice to truly stand out against even low volume music. So skip the music, because you don’t have time.
If you can’t avoid the temptation, then see this
https://nofilmschool.com/2015/05/simple-trick-will-make-your-dialogue-sound-better-stand-out
Now that you have a microphone, let’s get started!
Here is a great website with advice for voice overs.
https://www.musicianonamission.com/how-to-do-voice-overs/