Final answer:
An engineer uses a mixer to combine, control, and distribute audio signals. It allows for adjustment of volume, tone, and effects before sending it to the output.
Step-by-step explanation:
An engineer uses a mixer to combine, control, and distribute audio signals. A mixer is a device that allows the engineer to adjust the volume, tone, and effects of multiple audio sources before sending it to the output, such as speakers. It typically includes several input channels, each with its own control knobs to adjust the level and EQ settings.
While an amplifier is used to increase the amplitude or power of an audio signal, an equalizer is used to adjust the frequency response. The speaker is the output device that converts electrical signals into sound waves.