Brooke is learning about electronic devices that use electric current to encode information. She learns that when a person speaks into the microphone of a telephone, the sound wave generated by the person’s voice is changed into an electronic signal. This electronic signal is then transmitted to another telephone where it is converted back to a sound wave so the other person can hear the voice. The sound wave is encoded by varying the voltage of the electronic signal. Brooke learns that the voltage can be changed in two ways, resulting in two types of electronic signals: analog and digital. Figure 1 and Figure 2 represent these two types of signals.