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AFB  ®
Technology News for People Who Are Blind or Visually Impaired
From the American Foundation for the Blind
 September 2002 Issue  Volume 3  Number 5

Access Issues

Now Playing on Your Computer

There's no doubt that a personal computer (PC) with an Internet connection is a powerful tool for everyone, but it is especially powerful for visually impaired individuals. Much like the ways that sighted people use electric lights or reading glasses to do many different things, the Internet-connected PC is an interface to a wide range of activities. With a computer and a good screen reader or screen magnifier, you can read a newspaper, correspond with friends, check the weather, find out what's on TV, balance your bank statement, pay bills, browse a catalog, order products and services, trade stocks, research and plan a vacation, purchase travel or entertainment tickets, follow sports teams and game scores, research topics for school or personal development, play games, and more.

Sometimes other family members view using a PC as a single activity and make statements like "Are you still on that computer?" With a deeper understanding of the PC as a portal to facilitate all the different activities just enumerated, the question seems equivalent to asking a sighted person "Are you still using that lightbulb?"

The first part of this article dives right into Internet radio and voice chat. These sections are enough to get you started enjoying this entertainment source. Toward the end, some definitions are given for readers who want to understand how it all works.

Start the Music

To play web audio sources, you need a player—software that transfers the audio material to your sound card. Several different players are available free for download. Each has different features and devoted fans who tout its advantages over another. In fact, several web sites and mailing lists are devoted to specific player packages. Although some players can play proprietary audio formats exclusive to them, most will play several of the more common formats. Therefore, when getting started in web audio, you can pick essentially any one and later try others until you discover your favorite.

The more recent Microsoft operating systems come with Windows Media Player already installed. Another player that is popular with screen-reader users is Winamp from Nullsoft, a freeware package. You can learn more about Winamp at <www.winamp.com>. Configuration files for both JAWS for Windows and Window-Eyes are available for Winamp. You can learn about various versions of RealNetworks' RealPlayer, some free and some requiring a license fee, at <www.real.com>. A convenient and accessible place to obtain any of this software is from the download link on ACB Radio's main page at <www.acbradio.org>. This download page contains links to download any of the players just mentioned, along with the corresponding screen-reader configuration files.

Tune In

One fascinating development on the Internet has been the proliferation of web broadcasting. Web broadcasting allows a radio station's programming to be sent over the Internet as a series of IP (Internet Protocol) packets that contain digital audio. The term streaming audio is used to describe this technology. Digital signal processing (DSP) techniques are used to encode and compress the audio into a format that requires a fairly narrow bandwidth. A high-quality stereo program can be sent over a 28.8 Kbps dial-up Internet connection and still leave enough bandwidth available for e-mail or web surfing. Without compression, most Internet users could not listen to audio in real time. Other than the inconvenience of waiting, it really doesn't matter how long it takes to download a file to disk. But with streaming audio, one minute's worth of digital audio data must be transferred in one minute or less, or else there will be gaps or pauses in the audio while the computer waits for more data to arrive. These pauses significantly reduce the quality of the listening experience.

Many commercial, on-the-air radio stations offer Internet streaming audio access to their programs. Check your favorite radio station's home page, and you may find that you can listen to the station's broadcasts online. A good place to find radio stations is the radio station locator page at <www.radio-locator.com>. This site, previously known as the MIT list of radio stations on the Internet, includes an excellent search by call letters, city, or type of program. It lists all the radio stations, but indicates "BC" for those that offer bitcasting of their programs via the Internet. Clicking on the BC link next to these stations will bring up your default player and start the stream.

In addition to listening to on-the-air radio stations, there are many Internet-only broadcast streams to explore. The American Council of the Blind sponsors four channels of programming on ACB Radio. Go to <www.acbradio.org> to get started. There, you will find links to MainStream, featuring news, talk, and current events; the Café, showcasing the music of blind artists; Treasure Trove, a collection of old-time radio dramas; and ACB Radio Interactive, featuring live disk-jockey programs with listeners' requests. All these streams are available 24 hours a day. A program guide, as well as archives of prior content, are also provided on the site.

Time for Your Own Show

Anyone can start web broadcasting. Unlike commercial radio stations that require costly equipment and a license to operate, web broadcasting is open to all. There are no license requirements, and the typical home computer is sufficient to run the needed software. The ACB Radio Interactive channel features a collection of individuals who are interested in producing radio programs. The ACB Radio site has a section describing the necessary software and even offers a support group of others who will help you get started. This is a fine place to start, since their broadcasters are experienced users of the software with screen readers.

For a more general list of individual Internet broadcast programming, check out <www.live365.com>. There, you will find an extensive list of Internet broadcast streams. If that's not enough to fill all your listening hours, go to your favorite search engine and search for various terms, such as Internet broadcasting or Internet radio.

Let's Talk

The ultimate use of streaming audio is in voice-chat rooms. Conceptually, voice chat is similar to text chat using IRC or MSN Messenger, except that your voice, rather than your keystrokes, is sent to the other parties. Voice chat can be conducted using Microsoft's NetMeeting, as a part of the overall collaboration services offered by that software. However, for easy access to other participants who are interested in chatting, there are alternatives. Two sites that provide this service to many Internet users who are visually impaired are <www.audio-tips.com> and <www.for-the-people.com>.

To use the Audio-tips or For-the-People voice-chat services, you need a microphone and chat software. Many laptops have built-in microphones, and some newer desktop systems include them with the modem packages. If your PC doesn't have a microphone, you can get one at your local computer store or Radio Shack for under $20. Many people prefer a boom microphone built into headphones. As for the software, a small browser plug-in is downloaded to your PC. This software performs digitization and compression of your voice via a microphone plugged into your sound card. It also decompresses and decodes the received audio from other chat-room participants. The techniques are the same as those used in digitized streaming of audio in web broadcasting.

George Buys, the creator of Audio-tips, has established a free place for people to meet and chat on a variety of topics. His site includes a collection of chat rooms designated for various topics. On your first visit, you need to register and accept the automatic download of the plug-in software. Then you can enter any room and talk with other users of the site from around the world. There is a convenient conversation-locator frame on the main page, so you can tell who is currently in each chat room. If you come to the site at a time when no one is there, you should enter a room of interest anyway and wait. Once you have entered a room, your screen name will appear in the locator frame. As others notice that you are there, they can join the room to chat. Sometimes you may have a conversation with only one or two others, and sometimes as many as 15 or more people may be in the chat room at the same time.

Several organized discussions and training seminars take place on the Audio-tips site. These events are listed in a schedule that is posted on the site. Checking the schedule of events can help you find information about upcoming hosted discussions on specific topics of interest to you. But you aren't limited to existing events. Not only can you chat about anything of interest in the open rooms, but you can offer to host a special or recurring discussion on the site.

If you prefer more proactive notification of upcoming events, there is a mailing list to which you can subscribe. Subscribers receive periodic announcements of upcoming events and continue building relationships with other users. The sense of community among Audio-tips users is one of George Buys' greatest accomplishments with the site.

The For-the-People voice-chat site offers free voice-chat services similar to Audio-tips. As is true with local coffee shops or pubs, each of the two sites has regulars who frequent the chat rooms. Try them both and decide for yourself where you want to spend your voice-chat time.

What's Behind the Smoke and Mirrors?

Digital audio has been around for years. Compact disks (CDs) are the dominant medium for music. These CDs store one form of digitized audio. Other digital audio formats include the wave files found with the extension ".wav" on your PC and MP3 files found on computers and portable digital audio players. The name MP3 is short for MPEG Audio Layer 3, an international standard for a digital audio format. MPEG stands for Motion Picture Experts Group, which set the original audio/video standard.

The original source material is typically an analog audio source. Here, analog refers to the fact that the sound wave covers a continuous range, rather than a set of discrete numeric values. To illustrate, your height is an analog value, but when it is measured in whole inches, the fine details of any fraction of an inch are lost in the whole-number, digital representation.

The analog audio is a waveform. To understand, think of waves on the ocean. Two elements are important: the height of the wave, called amplitude, and the number of waves that pass by over a certain period, called frequency. The height of the wave is dependant on the volume of the sound. The frequency, the number of waves that pass by each second, is determined by the pitch of the sound. This analog waveform eventually drives a speaker or headphone. The frequency of the electronic analog waveform causes the internal surface of the speaker or headphone to move in and out at a particular speed, generating a specific sound pitch. Higher frequency means more rapid movement and thus a higher pitch. The amplitude of the electronic analog wave controls how far the speaker surface moves in and out with each wave and thus controls the volume of the sound. Higher amplitude means more speaker movement, which means louder sound.

Is There More?

If you want to dive deeper, check out the resources listed at the end of this article. If these are not enough, there are mailing lists covering a range of PC audio topics described further on the Winamp-for-the-blind web page. One informative list devoted to digital music issues for blind individuals is PC-audio. You can subscribe by sending an e-mail message to <pc-audio-subscribe@yahoogroups.com>.

Resources

Speak Freely, an Internet-to-Internet PC phone package. Visit <www.acbradio.org/download.html> for links to the software and tutorial information.

CD Ripping, extracting the audio from a CD into PC audio files. Visit <www.poikosoft.com> for a shareware package called Easy CD DA Extractor.

Winamp, one of the players mentioned earlier. Visit <www.shannon.reece.net/Winamp4TheBlind.html> for tips and some interesting Winamp plug-ins.

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