by Al Lemieux
Using audio in your online course is an extremely important factor in engaging your audience. Studies have shown that courses without audio are less compelling and memorable than courses with audio. Either used as a narration or for directions, audio - done the right way - can greatly enhance your e-learning materials.
Help with Audio for Online Course Developers
Audio engineering and the knowledge it takes to adequately capture, edit, and clean up audio to achieve a quality output is a task that is typically beyond the skill set of most online course developers. The average course developer has little if any knowledge of sampling rates, frequencies, modulation, compression schemes and other audio engineering concepts.
The goal of this article is to provide you information on how to get the audio in a format suitable for an eLearning course-authoring tool (such as Captivate). The article will focus on capturing and editing audio at the basic level and certainly, the tips listed below should help get you moving in the right direction.
Microphones
For narration, you'll need to use a microphone to capture the voiceover. Sure, your laptop or PC might have a built-in microphone, but you probably don't want to end up sounding like the broken drive-thru speaker at your local fast food restaurant. There are several microphones to choose from and they are made specifically for different purposes.
Dynamic Microphones are the ones you commonly see being used by rock stars in concerts. They have a ball-like shape as the head. These mics are omni-directional, meaning that they can pick up sound from a wide area. The Shure SM-58 microphone is an example of a dynamic microphone and has a consistent quality and dynamic range that makes it useful for all types of applications.
Condenser Microphones, unlike dynamic microphones, have a capacitor inside that requires them to be powered by a source - either battery or A/C. These microphones are often found in recording studios, used in live concerts, and are commonly found in lavalier mics (the kind you attach to a shirt or lapel). These mics are uni-directional, meaning that they capture a more narrow area of sound. Because of their power requirements, their voltage output can vary. The Neumann KMS-105 is an example of a condenser mic.
You may also find a Headset Microphone, which plugs directly into your computer's input source and output source, so you can hear what you say as you are recording. Most of the microphones on these headsets have a noise cancellation function built into them. This causes unnatural sounding silences between phrases. The audio quality from these types of microphones tends also to sound blown out as the microphone position is very close to the mouth. That makes higher frequencies tend to sound noisy and lower frequencies sound poorly.
Built-In Microphones have the tendency to pick up any noise generated by your computer during use. This means any hard-drive motion, cooling fans, operating system sounds, and room ambience. These microphones are usually engineered to pick up the widest area of sound for situations like web conferencing and chat room sessions. The audio quality is usually poor and the microphones do not have sophisticated features like noise canceling or balancing. If at all possible, you should avoid using the built-in microphone for your audio input source.
Distance from Microphone
I'm sure you've all seen the rock videos or American Idol, where the rock stars have the microphone jammed up against their mouths as they are singing. So most people feel they need to do the same when recording narration. What the rock stars have to their advantage is a sound limiter that cuts off frequencies above a certain range. The maximum output is policed by this device to prevent any unwanted feedback or squelch, because the frequency is automatically limited. Most likely, your simple setup won't have this capability.
One thing you can do to prevent any unwanted sounds in your narration, is to position your mouth about 6 to 12 inches away from the microphone and speak directly into the microphone, not away from it, to either side, nor in front of it. The best audio signal will be a direct path from your mouth to the microphone. If you start speaking into the microphone and then tilt your head downwards to read from a script, you'll be able to notice the drop in the audio signal. If needed, hold your script up next to the microphone. Another tip: when reading from a script, don't read across pages that you are turning or moving from one hand to another. Most microphones are sensitive enough to pick up all of that paper moving. If possible, have each page of the script segmented and keep them separated, not stapled or kept together with paper clips.
Use a Windscreen
A consistent frequency helps to produce the best audio. If you are looking at an audio waveform for the first time, you won't be able to decipher it, but the peaks and valleys of each frequency can visually tell a lot about that sound. One thing that often happens, especially during narration recording, are pops that occur when saying words that begin with P or B. These pops go above the dynamic range and therefore, don't sound anything like a P or a B but more like a popping sound.
A simple solution to this problem is a windscreen. Some engineers will wrap a wire clothes hanger with nylon stockings and place them in front of the mics in order to act as a low budget windscreen, but you can also buy them for less than ten dollars at your local music store. These are constructed out of a foam material and fit over your microphone.
Interfaces
So far, I've spent a lot of time talking about microphones but a majority of the mics recommended here won't even plug in to your computers without adapters. Professional mics have an XLR connector, which has three pins. Most computers are made with eighth inch connectors. You can use Dynamic Microphones with an adapter connected to your computer without much of a problem. Condenser Mics, since they require power, won't work even with an adapter.
There are interfaces specifically built for this purpose and they come in two flavors: USB and Firewire (IEEE 1394). Most PC manufacturers are including either USB 1.0 or 2.0 ports on their hardware. Firewire is more commonly found on Apple computers however, you can purchase Firewire cards for PCs. Firewire is faster than USB in certain applications and therefore is more desirable for audio input. There's less latency on a Firewire connection than on a USB connection because of the performance speed.
Firewire comes in two flavors, there's Firewire 400, which can transfer data at a rate of 400 MB per second, and Firewire 800, which doubles the speed to 800 MB per second. There are a wide range of musical digital interfaces out on the market today, and you can use either of these technologies to interface with a computer. M-Audio has a line of both types including the ProFire 610 and the FastTrack USB.
These devices can run off of their intended connections and act as an audio input/output source for your computer to provide a professional recording result. At SyberWorks, we use an M-Audio Firewire 410 audio interface connected to two Shure-SM 58s for all of our narration. The 410 is a powerful choice because it offers multiple inputs and all of the audio controls necessary for level/gain and limiter/compressor. It also has XLR inputs and quarter inch inputs for microphones and instruments, and two headphone outputs. Connected to the 410 are two M-Audio BX8a monitors, which offer a much higher quality output sound than any built-in computer speaker.
Software
There are so many options for audio editing software, from the simple shareware/freeware to the professional level, that the determination of what to use might lie somewhere within your budget constraints. The basic audio recording tools that come with any Windows-based machine do not generate quality audio. Any Apple computer comes with GarageBand which is an excellent mid-level audio recording application. GarageBand is the step child of Apple's Logic Studio and offers some pretty sophisticated tools for recording, editing, and delivering audio recordings on any platform.
Adobe has an audio recording/editing application called SoundBooth, which offers a variety of tools for cleaning up audio files and saving them in different formats. SoundBooth comes with the Creative Suite Production Premium or Master Collection. I recently used SoundBooth to record old cassette tape tracks as MP3 files so that I can burn the files to CD. I was able to use SoundBooth to clean up all of hissing sound on tapes and the audio quality was excellent.
Bias, Inc. has been in the audio production area for over a decade now and their flagship audio editing software, Peak Pro, is an award winning application. With a simple interface and a variety of effects and controls, Peak makes audio editing simple. I'm a long time user of Peak Pro and can say that it's a stable, professional application that offers all of the tools that I need to edit the audio that I record. Combined with SoundSoap Pro, an audio cleaning application, Peak Pro can reduce noise, hiss, rumble, cracks and pops, and other unwanted sounds from any audio recording.
Here at SyberWorks, we use Peak Pro to record any narration for podcasts or courses and GarageBand to stitch together podcasts and teasers. GarageBand comes with some preset stingers and effects which are great for podcasts. It's ridiculously easy to use. Once the file has been put together, it's output as an AIFF file to iTunes. I then use iTunes to convert the sound to the MP3 format for delivery.
Next Week: 5 More Tips for Capturing eLearning Audio
About the author: Al Lemieux is a Senior Designer at SyberWorks, Inc. SyberWorks, Inc. is a leader in the custom e-Learning Solutions and Learning Management System industries for Fortune 1000 corporations, higher education, and other organizations. Located in Waltham, Massachusetts, the company serves the multi-billion-dollar e-Learning market. Since 1995, SyberWorks has developed and delivered unique and economical solutions to create, manage, measure, and improve e-Learning programs at companies and organizations in the United States, Canada, Europe, and other countries.
Thanks for the article - great information. I would also suggest to those who have never used an audio editing software the program called Audacity, very easy to learn and it's FREE! However in order to export the files as an MP3 you must download a separate plug-in.
Posted by: Chelsey Slack | July 24, 2009 at 11:33 AM