Using sound to help the message

Here we have three different soundtracks for a section of an imaginary multimedia presentation about the discovery of the planet Pluto - the outermost planet and shown in the NASA image below - by Clyde Tombaugh in 1930.

There are three versions of the recording, with different degrees of attention to style and quality. You should click on the links and your browser should then open and play the files in another window.

Version 1 (312 KBytes) is recorded with a basic microphone and with little attention to the intonation of the speaker.

Version 2 (304 KBytes) has a more professional approach to the voiceover and the recording. You should be able to see how the second one is easier to listen to than the first.

Finally, we add music in Version 3 (364 KBytes). Because the text is dealing with the planet Pluto, and this is a cold and isolated place, the music sets a mood that matches this. You will notice that the speech is the same recording as track 3 but that the timing has been adjusted slightly to allow for the music.

The improvement in the recording between the tracks is also matched by a potential incease in cost. A professional voice will cost money and you will probably want to use a sound studio rather than, say, record in the office. Adding music not only adds the cost of the music itself but also the equipment and time needed to mix the sounds together.

The unworldy feel of this example is added to by a further, gratuitous, illustration. The audio files on this web site are encoded using MP3 (otherwise MPEG audio Layer 3) and this reduces the data in a sound file by removing parts of the sound that we do not actually hear because they are, for example, masked out by other sounds.

This final sound file (364 KBytes) demonstrates what the MP3 processing removes from the sounds in the third version of this presentation as it compresses the file. It was made by compressing the file quite heavily, converting the result back into an 'uncompressed' audio file and then subtracting this result from the original. Borg anyone?

Long-range image showing surface features of Pluto.

Image Credit: Alan Stern (Southwest Research Institute), Marc Buie (Lowell Observatory), NASA and ESA