The title of this post is a lie. It costs $70 or less, but takes a lot of work. I’ve offered this advice person-to-person many times, and finally got around to posting it.
How well you speak can have a great impact on your ability to get customers, to attract employees, to persuade others to adopt your ideas, and much more. But how do you know how well you speak? You can’t tell as you are speaking; and if you’ve never heard yourself speak but simply assume you do well, there is a great risk that you are very, very wrong.
To become a better speaker, you need to review your own “performances”. For the last few years I’ve been recording my talks (at user groups etc.) with a hand-held voice recorder. I use an Olympus WS-100 (probably obsolete by now) and you can readily find an adequate device for $70 or less.
Make the Recording
Don’t actually hold the recorder on your hand. Sit it on the podium if you use one (I don’t care for podiums, I use one only if I am presenting with my computer and the podium is the only place to put the computer); but not to close to your noisy computer. Put it on a table or unused chair in the first row, but not too close to any noisy people or equipment.
Start it at the very beginning, and stop it at the very end. It is easy to edit out extra recording later.
Put in a fresh battery, so it doesn’t run out partway through.
Listen to the Recording
Take the recorder/player in your car, copy it to your iPod, burn to CD, whatever… but listen to it, end to end. Experience your talk as a member of the audience. Make notes about any bad habits you exhibit, such as “umm”, “ahh”, “like”, “ya-know”, long (unintentional) pauses, pointless extra words, etc. This is your first opportunity to become a better speaker by means of the recording. WARNING! The first few times this might be very, very painful.
Edit the Recording
If you plan to post this audio online (as I usually do), clean up the recording to trim off any extra starting and ending time; the audio you post should start immediately with your talk content and end crisply. Download Audacity (or another audio editing) and use it for this initial trim.
If you can spare the time (approximately 2x the length of the talk), listen through the whole recording in Audacity, trimming out the “umms”, “ahs”, overly long pauses, etc. This is your second opportunity to become a better speaker… but only for the offline listeners, and in an artificial, one-off way. Still, for an occasional important talk it is worthwhile.
Get a Transcript
Finally, be aware that your (now-pristine) audio is completely unsearchable and invisible to Google. To make it findable, have a transcript made and post that also. You can pay CastingWords or other similar service to create a transcript for around a dollar per minute, or perhaps much more cheaply with some searching. The resulting text can be readily posted online, making your talk both more findable, and more accessible.
An example of a recorded, lightly edited, and posted talk (with transcript) is my Ruby GUI talk earlier this year.