Chapter 5: Understanding Audio Special Effects

In Chapter 4, you learned how to programmatically create audio special effects by using DirectSound. This chapter provides more information about when to use the various audio effects, what the individual settings mean, and how to tweak the settings to create various effects that you might want to add to sounds. This chapter won t introduce any new code; you ll simply use the Rumpus sample to learn about creating the audio effects that you want.

This chapter also provides some basic information about the nature of sound in order to aid the discussion of the various audio special effects.

Why Use Audio Effects?

There was a time when the soundtracks that accompanied computer games consisted of a cacophony of beeps and monophonic tones. Around the same time, the types of media available to consumers, such as videotapes for viewing movies or compact cassettes for music listening, provided varying levels of quality. Consumers willing to spend large sums of money could enjoy video and music that delivered relatively high fidelity, but this was no guarantee that the content originators would make the investment in creating source material that delivered a great experience. After all, if most viewers or listeners didn t have the equipment to reproduce a presentation with stunning realism , why spend the time and money to implement the required technologies during the production phase?

Things have changed drastically since those days. Compact disc (CD) audio has become the standard for music playback, delivering noise-free, high-fidelity playback for everyone. Digital video disc (DVD) technology has brought the same kind of audio and video quality into homes at a price point that most can afford. Multichannel surround-sound systems are becoming more common in homes , providing consumers with an experience to rival the best movie theater presentations, and Hollywood is providing the soundtrack content to deliver an immersive audio experience.

The audio technology available for personal computers has advanced in the same way. Modern sound cards are a far cry from the tone generators of the past; they can create the same high-fidelity experience that consumers have come to expect from Hollywood motion pictures. Manufacturers who used to create speaker systems solely for the audiophile market now sell multichannel, surround-sound speaker systems designed exclusively for personal computers. In fact, many consumers use personal computers as DVD playback systems. Game developers can now expect that players have the equipment they need to faithfully reproduce a soundtrack. Indeed, a game that fails to deliver a convincing audio experience may disappoint today s savvy player.

The difference between a soundtrack that pulls the player into the virtual world of the computer game and a soundtrack that sounds flat and unconvincing can be the intelligent use (or lack) of audio special effects. Audio special effects can enhance sound in many ways, including the following:

• Make a sound recorded in one type of space sound like it is occurring in a completely different environment.

• Make several sounds recorded separately seem like they are occurring in the same environment simultaneously .

• Create an environment that does not exist in the real world.

• Create a sound that does not occur naturally.

• Enhance musical performances .

• Compensate for inconsistencies between various soundtrack elements.

The remainder of this chapter explores the audio effects available to you when using DirectSound.