|media type:||digital audio|
|what it does well:||historic events, narration, providing environmental cues, background music, grabbing attention|
|issue to consider||rating||comments|
|"hurdle" or barrier for creating media||low high
||Hardware needed to digitize sounds is commonly built into most newer computers and may be as simple as a microphone. Free or low coast shareware can be used to edit and modify sound, and many sites exist with downloadable audio files.|
|"breadth" of audience that can view media||narrow wide
||Most recent computers have built in ability to play back sound and it is typically built into most web browsers. Many people will have their volume turned down.|
|bandwidth consumption||low high
||Can be quite large but is much less than video. Small sound effect files can be small and some sound file formats (MIDI) are designed to be very small in size. Options exist to "stream" content but it may require special servers.|
Sound is one of our most crucial human senses for receiving information and it can be used very effectively for web sites.
However, as you visit different web sites, the main time you come across sound is hearing some corny rendition of marching music, some vague familiar television show theme song, or tinker-toned Beethoven as soon as a web page loads. When a designer adds irrelevant graphics to a work, it is called "Eye Candy"; using sound for many web sites amounts to "Ear Candy".
"So, M. Opinionated, when is sound good?" Good question. Audio can be very useful for re-casting historic moments (speeches, special events, news, etc). It often is a less bandwidth alternative to video when the content is mostly spoken (e.g. classroom lecture). Obviously it might be used to learn about music and acoustics, to compare renditions of classic works, and simply to entertain-- the web can act as a radio. Sound may be used to set an environment (soft music for reading a poem).
Like video, sound must be converted analog to digital, from audio waves that travel through air, to numerical representations of wave frequencies. It can be done as easily as talking into a microphone plugged into the back of your computer, to high end digital recording in a sound studio. In the end, you end up with a computer file that can be played back through a speaker and, again travels through the air to your ears.
Sound files come in many different formats, which creates another layer of alphabet soup confusion. Some of the common file formats are WAVE (WAV), AIFF, AU, MIDI, MP3 etc. A comprehensive overview of the differences between them is beyond our tutorial, and we will just have to accept that we can have a sound file on a computer that can be sent over the Internet and played at the other end.
One format is of special interest, MIDI, because it generally makes for the smallest sound files. Rather than digitizing the sound waves itself, in MIDI format sounds are represented as more or less text characters representing the notes on different types of instruments, and when it is played back, the computer uses a built in sound library to play back the designated note. Therefore, the data that sent is very small. MIDI sounds tend to have a "toy-like" playback and are no where as rich as a CD audio.
Many sites offer sound in RealAudio format in which the sound files streams from a special web server to your web browser. This is most efficient for so called "web radio" stations, sites that offer real time audio news feeds, sites that promote musical events, etc (e.g. World Radio Network, RadioTower, Broadtcast.com, NPR, CNN). Because it requires special equipment, RealAudio is not part of this tutorial.
We also should mentioned the format known as MP3, or MPEG Audio Layer 3, a special form of high quality audio that can compress a very rich sound file into a much smaller file. It may be a music format that changes the music industry. You can find many sites such as MP3.com that offer MP3 music, but again, encoding content into this special format calls for special hardware and software (and touches on tricky legal issues of encoding other artist's content).
For more information on audio over the web, see the Web Developer's Virtual Library for Audio for the WorldWide Web
To include a sound file in a web page, we typically use the same <embed> tag that we saw in the previous lesson on web video:
<embed src="muzak.wav" autoplay=true controller=false></embed>
which is the typical way to write a sound file that will be played automatically as soon as a web page is opened, and by having the controller invisible, to the person seeing your page, the music just starts playing magically. If you want to provide them the choice of playing the sound or not, you would have the controller visible and the autoplay set to false:
<embed src="muzak.wav" autoplay=false controller=true></embed>
Again, if you are going to use music or sound in your web page, think carefully about the purpose of the content and if it will be reasonable to hear it every time a person goes to that page. You should never assume that the audio will work for every visitor (and some visitors are deaf), so consider providing text alternatives or suggestions for people that may not be able to hear the content.
Note: If you do not have the working documents from the previous lessons, download them now.
In this lesson, we are going to add some audio content to our main volcano web page. To add some relevancy to the importance of Volcanoes, we will use content from a letter written by an observer of the volcano Vesuvius, which in the year 79 AD destroyed the city of Pompeii. Along with the text of the letter, we have an audio recording read by a starving actor pretending to be the writer, plus a photo of one of the remains of an actual victims of this event. In this treatment, we provide information in written, visual and audio formats!
The sound file we use is actually saved in the format of a QuickTime digital video, with no video, only the sound track, to take advantage of the wide support for QuickTime in web pages and the advanced file compression available for this format. Plus we can save it in the format that streams it from a web server. The file could also have been a WAV or AIF file.
NOTE: We have written a new web page with a title, some introductory text, a footer, and the <embed> tag to include a control that will allow the site visitor to play a QuickTime sound file.
Now we will add some more content, the text of the letter, inside a HTML table, with a right aligned image.
<p> <table border=0 cellpadding=6 cellspacing=1 width=70%> <tr> <td><font size=+1 color=#FF9999> The carts that we had ordered brought were moving in opposite directions, though the ground was perfectly flat, and they wouldn't stay in place even with their wheels blocked by stones. In addition, it seemed as though the sea was being sucked backwards, as if it were being pushed back by the shaking of the land. Certainly the shoreline moved outwards, and many sea creatures were left on dry sand. Behind us were frightening dark clouds, rent by lightning twisted and hurled, opening to reveal huge figures of flame. These were like lightning, but bigger. At that point the Spanish friend urged us strongly: "If your brother and uncle is alive, he wants you to be safe. If he has perished, he wanted you to survive him. So why are you reluctant to escape?" We responded that we would not look to our own safety as long as we were uncertain about his. Waiting no longer, he took himself off from the danger at a mad pace. It wasn't long thereafter that the cloud stretched down to the ground and covered the sea. It girdled Capri and made it vanish, it hid Misenum's promontory. Then my mother began to beg and urge and order me to flee however I might, saying that a youngs man could make it, that she, weighed down in years and body, would die happy if she escaped being the cause of my death. I replied that I wouldn't save myself without her, and then I took her hand and made her walk a little faster. She obeyed with difficulty, and blamed herself for delaying me. <p> Now came the dust, though still thinly. I look back: a dense cloud looms behind us, following us like a flood poured across the land. "Let us turn aside while we can still see, lest we be knocked over in the street and crushed by the crowd of our companions." We had scarcely sat down when a darkness came that was not like a moonless or cloudy night, but more like the black of closed and unlighted rooms. You could hear women lamenting, children crying, men shouting. <img src="../pictures/bodies.jpg" alt="bodies buried in ash" width="358" height="135" align="right">Some were calling for parents, others for children or spouses; they could only recognize them by their voices. Some bemoaned their own lot, other that of their near and dear. There were some so afraid of death that they prayed for death. Many raised their hands to the gods, and even more believed that there were no gods any longer and that this was one last unending night for the world. Nor were we without people who magnified real dangers with fictitious horrors. Some announced that one or another part of Misenum had collapsed or burned; lies, but they found believers. It grew lighter, though that seemed not a return of day, but a sign that the fire was approaching. The fire itself actually stopped some distance away, but darkness and ashes came again, a great weight of them. We stood up and shook the ash off again and again, otherwise we would have been covered with it and crushed by the weight. I might boast that no groan escaped me in such perils, no cowardly word, but that I believed that I was perishing with the world, and the world with me, which was a great consolation for death. <p> At last the cloud thinned out and dwindled to no more than smoke or fog. Soon there was real daylight. The sun was even shining, though with the lurid glow it has after an eclipse. The sight that met our still terrified eyes was a changed world, buried in ash like snow. We returned to Misenum and took care of our bodily needs, but spent the night dangling between hope and fear. Fear was the stronger, for the earth was still quaking and a number of people who had gone mad were mocking the evils that had happened to them and others with terrifying prognostications. We still refused to go until we heard news of my uncle, although we had felt danger and expected more. <p> You will read what I have written, but will not take up your pen, as the material is not the stuff of history. You have only yourself to blame if it seems not even proper stuff for a letter. Farewell. </td> </tr> </table> <p> <font size=2>Pliny the Younger's Letter, text from the <a href="http://www.iath.virginia.edu/pompeii/pliny.html">Pompeii Project</a><br> Pictures of Pompeii victims, from <a href="http://www.geo.mtu.edu/~boris/VESUVIO_79.html">photos taken in 1992 by Werner Keller</a>.</font> <p> <font size=+2>If this historic account shows you<br> the impact of a volcano on human life, <a href="index1.html">continue on ...</a></font>
NOTE: There is nothing new in this section, so you can easily copy and paste it to your HTML. Note that we have included an image file inside the table and allowed the text to trap around it. Below the table are some links to related source materials as well as a link to our main Volcano web site.
who died of asphyxiation after observing the destruction of Pompeii by the 79 A.D. eruption of Mount Vesuvius.add this line:
<a href="pliny.html">"Hear" Pliny's account!</a>
Compare your web pages with this sample of how it should appear. If your pages are different from the sample or the hypertext links do not work correctly, review the text you entered in the text editor. Compare your work to the HTML of the samples (look for something like Source from your browser's View menu).
Like you saw in our previous lesson on video, the QuickTime movie format we used here for the sound file may not work for everybody. You can use the same HTMl code to play back a sound in WAVE format. However, keep in mmind the QuickTime employs a great deal of effective compression to reduce the file size of a sound file; the 360k sound file in QuickTime format is 10 times as big (3.2 MB) as a .wav file!
We have not included the WAVE file in the downloaded version of the tutorial, but you can find it from our main web site, as files:
Once you download the sound file from the Lesson 28c Sound Studio, you can simply substitute all HTML references to pliny.mov with the new file name, pliny.wav.
Try adding some sound to your own web pages. Before you use any sound files in a published web page, be sure to obtain permission from the person that created it.
You can always build a link to any media file by using our familiar hypertext link:
Try out my latest <a href="new_riff.wav">guitar riff</a> or <a href="trumpet.mid">trumpet call</a>
assuming we had a WAV file and a MIDI file with these names. The web browser will leave the page it was linked from and then try to load the sounds the best it can, in blank web page. After hearing the sound, you would have to press the browser back button to return to the page you came from. The implementation is not as seamless as embedding it in the page but it works.
Stand back and brace yourself... a S H O C K W A V E! is coming
Writing HTML: Lesson 29c: Sound of [web] Music
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