Answer:
In a portable stereo, electrical energy is changed to sound energy
Step-by-step explanation:
A portable stereo is an electronic device that has the capability of transforming various forms of inputs such as Compact Discs, USBs, Bluetooth, radio frequency as well as microphone that carry information that is converted through processing within the stereo and put out as sound. That is a portable stereo changes electrical energy input into coded sound energy.