With the Handihams Patrick Tice, WAØTDA wa0tda@arrl.net Recording for the Blind Part One Most of us take being able to read a book or an instruction manual for granted. If we take an amateur radio licensing course, most often we will buy a book and use it in our studies. The print manual packaged with a new radio is a good reference for those of us who can see to read it. For those who cannot read regular print, there must be alternatives. We serve Handiham members who are blind or who have a reading disability with accessible website materials that include spoken word audio. These days, computers are excellent blind accessibility tools and are equipped with screen reading software so that blind users can operate them independently. A skilled blind computer user can navigate and read a PDF transceiver instruction manual online. Years ago there was no other way to access instruction manuals except by having a volunteer read the entire contents of the manual onto cassette tape. A master tape then provided unlimited copies for Handiham members who had that particular radio. Similarly, license study materials used to be available only in print and had to be read by volunteers. Today there are many other options that include audio compact discs and websites designed to teach amateur radio. None of these options has really been designed from the ground up for the use of blind amateur radio operators. Instruction manuals, for example, even if they can be read by screen reading software, usually contain undescribed diagrams and confusing sidebars and tables that are hard to keep in context. Nothing in these manuals describes where the controls are located on the front panel of the radio because there is a diagram complete with labels, which of course a blind person cannot see. Licensing materials also contain figures and diagrams as well as mathematical equations that are not described well from a blind perspective. At The Courage Center Handiham System we have decided to take a different approach. Instead of simply having a human volunteer read an instruction manual for a transceiver from one end to the other, we instead ask a volunteer who owns and is familiar with that particular radio to instead "teach" about that radio, recording an audio tutorial series that blind hams will find more useful. The volunteer instructor will teach the course at his or her own pace just as if they were explaining the radio to a person on the other end of a telephone line. Licensing courses are taught the same way, with extra explanation of what an algebraic formula looks like or what a schematic symbol looks like. Volunteers can use the free, open-source software program Audacity. Let's take a look at how you can try recording for yourself. Perhaps you will be able to help us produce some new audio tutorials!
First, get Audacity. Head for http://audacity.sourceforge.net. Audacity is a cross-platform sound editor. Not only is it free, but it will work on several different operating systems. I use Windows, so my choice was the latest release, 1.313 beta.
You will also need the LAME MP3 encoder in order to create the final MP3 audio files. However, you do not have to download and install the LAME encoder right away. Instead, install Audacity, then open the software and familiarize yourself with the menus. At first the controls near the top of the window might look a little confusing, but they are not all going to be used for a typical recording session anyway. You can see the familiar symbols associated with recording and playback on the round buttons, and they work just as you would expect. Install and check your microphone. Before making your first recording, you will need to have a microphone hooked up to your computer. All modern notebook computers have built-in microphones, but whether you are using a desktop machine or a notebook, an external microphone is probably going to give much better results than a built-in condenser microphone. I recommend a USB headset microphone. In this photo, you can see the Logitech USB headset microphone that I use for my recording, and you can listen to a sample when you finish reading the article and go to the web link that I will provide. For best audio quality, be sure you
have a foam shield over the microphone to avoid "pops" should your breath cross the microphone element. Believe me, it makes a difference! Set up your computer s sound. I use Windows 7 Professional 64 Bit, and this is what my sound recording setup looks like. If you are using Windows, find the little speaker in the taskbar on the lower right corner of your screen. Right click the speaker with your mouse and choose "recording devices". Click on the "Recording tab. Now you should see something that looks like a list of devices from which you can record.
As you can see, I have several choices here. I have to be sure that I highlight the right one, and I know from experience that "Microphone USB Audio Device", which I have set up as the default recording device, is the Logitech USB headset. Had I made a mistake and chosen "Microphone USB Audio Codec" just above it, my recordings would come from the receiver audio of my connected ICOM IC-7200 transceiver! Of course you can use Audacity to record from a variety of sources, but we will leave that for another time.
Next, we have to make sure that our audio levels are correct. Click on the "Properties" button and when the next screen comes up, choose the "Levels" tab and adjust the microphone slider. I discovered that a setting of 73 (a number that I can easily remember for some reason) provides a nice waveform for my voice without clipping. However, there is one more adjustment to check.
While you are still in that same window, click the "Custom" tab and then put a checkmark in the AGC box. If the audio proves to be too hot and the waveform is clipped and distorted, you can uncheck this box later on, but I find that it is necessary to check it to get adequate volume. Since all computer systems are different, you will have to experiment with your audio settings. Some sound cards don't even offer this AGC feature, so don't be concerned if you can't find it. Make your first recording! Now you are ready to make a recording. Go back to the main Audacity screen and click the red record button. Notice that my USB microphone is selected. Let's take a look at what a screen of waveforms looks like:
The screenshot shows an audio lecture that I have made on rectifiers for my General Class students. It is in its most basic raw format, and you can see that there are nine separate tracks. The recording begins on the far upper left corner. I got into the recording a few minutes and then had to stop. I resumed recording and stopped again, which made the second track. Then I recorded the third track, stopping again before starting the fourth track, and so on. In order to stop the recording I just used the stop button that has the typical symbol for "stop", a square. Whenever I started recording the next track, I made sure that the cursor was all the way at the end of the previous recording by using the fast forward button. That way I am sure that none of these tracks will overlap. As you might guess, when you are teaching a lesson there will be times when you have to stop to answer the phone, take the dog out, look something up in a reference book, or just stop recording because you want to be done for the day and work some DX. In order to make sure that you don't lose anything, simply use the file menu in the far upper left and choose "save project as", giving it a filename that you can remember and storing it in a place that you can find when you are ready to resume recording. When you do this, Audacity creates an aup file, which you will click on when you want to continue the recording. There will also be a file folder with the audio data for the aup file and it will be similarly named. Both must be kept in the same directory while you are working on the recording. Get in the habit of saving your work often. Edit and process the raw audio.
My next step is to select all of the tracks and turn them into one single track. Remember, the audio from these tracks cannot overlap. That's why you can see the audio starting on the far left and continuing all the way through to the far right. In fact, if you want to listen to anything you have recorded, you can just place the cursor anywhere in any of these tracks with a mouse click and then click the round button with the green play triangle to listen. The audio will play from track to track without interruption. Of course all we need is a single track, so we need to select all of these tracks by using the key combination CTRL+A or the Edit menu on the top and choosing "Select All". Next, from the "Tracks" menu on the top choose "Mix and Render" to combine all of these tracks into one single track.
This certainly looks simpler, doesn't it? Now we have a single track, and you can see that the waveform seems okay and not clipped, but there are obvious gaps of silence that we are going to have to edit out. Fortunately, this is easy to do with Audacity.
Using the "Effect" menu at the top, choose "Truncate Silence" from the pulldown menu. A dialogue box will appear and you will need to either use the default settings or enter the numbers that I have put in after experimenting with what works best. I suggest that you start with my settings for the best results. The software will then locate and remove any silence in the recording that is longer than 500 ms with a threshold of -25 db used as the standard.
Now that the silence has been removed and the waveform looks more or less continuous, we are going to touch up the levels. This is done by going to the "Effect" menu at the top and choosing "Leveller". A dialogue box appears and you can choose the degree of leveling that you prefer. I like the "Light" setting because it produces no distortion. It will help level the volume throughout the entire recording. Make an MP3 file.
In this example, I am recording lecture number 14 in my General Class series. Since I have already saved the project with the file name 14_gen.aup, I am now ready to export the file to MP3 format. You may be expecting the more familiar save as, but export will do the same thing. You will find the Export choice under the File menu on the top left. If the LAME encoder for MP3 is not installed, you will be prompted to do so now. Follow the instructions. Then you will be ready to continue by entering the metadata, which is optional. I always enter it because it tags the file with relevant information such as a brief description of the contents, the author, and so on. Here is a screenshot:
You can save the metadata file separately for use later on. Give it a file name descriptive of what it contains, such as general and hit the Save button. When you click the OK button at the bottom the actual export process begins. The MP3 file will have the same name as the Audacity project, except with the familiar MP3 file extension.
In this screenshot, you can see the export process underway. The quality level I have chosen for spoken word audio is 40 Kbps. That will save space on my hard drive because the file size will be much smaller than if I had chosen the default 128 Kbps stereo.
Almost done! Now I can see the icon of my new MP3 file on my Windows desktop. It is time to click on the file and listen to the audio to make sure it sounds okay. I use the default player, Windows Media Player, but you might use another player, such as itunes.
Note that the file plays and the metadata scrolls across the screen of the player. You have produced your first MP3 audio file using Audacity! Here is a short sample of the audio lecture that was shown in the screenshots above. Just follow the link right from your WorldRadio Online: http://handiham.org/audio/lecture_sample.mp3 Next time we will discuss some techniques about how to describe a radio and how to do some audio teaching. I hope you will consider helping us add to our collection of audio training lectures! Please visit us on line at www.handiham.org and subscribe to our weekly e-letter in HTML or audio, available from the itunes store as a free podcast. Courage Center Handiham System 3915 Golden Valley Road Golden Valley, MN 55422 Toll-Free: 1-866-426-3442 Email: hamradio@couragecenter.org