Sound is one of the foundations of human interaction. It serves as the conduit for free speech, conveys the emotional appeal in music, and most importantly, is the most commonly used vehicle for interpersonal communication. Sound in technology provides users with the ability to control how, when, and where the user hears and responds to other people as well as systems. Peoples' desire to interact by way of sound and to manipulate sounds can be seen in the rapid adoption by mainstream consumers of the telephone, tape recorder, audio mixing boards, and the CB radio. Digital, interactive networks and the devices that connect to them will provide the next generation of consumers with even greater personal control over the power of sound.

This chapter explores three ways in which consumers' expectations and uses of sound impact the evolution of digital networks. First, we take a look at how digital networks evolved from communication networks. Then we examine how digital networks change and extend how consumers buy and use music. Finally, we explore the services that sit on top of the digital networks to help consumers use the power of voice to drive device behavior. After reading this chapter, you should have a good understanding of the following topics:

• How sound has evolved through interactive technologies

• How consumers have responded to the evolution of interactive sound

• How the evolution of digital networks help create a marketplace that address the needs of the interactive consumer

Let's start by taking a look at how sound has evolved in computers.