Final answer:
A piano and a steamer can produce sound without electricity; a piano uses mechanical action, and a steamer can use steam pressure to whistle. An electric piano needs power for digital sound or amplification, while a hairdryer requires electricity for its motor and heat elements to create sound and heat.
Step-by-step explanation:
The question asks about two items from the list of four - piano, electric piano, hairdryer, or steamer - which do not require electricity to produce sound. Among the given options, the piano and the steamer can produce sound without the need for electricity.
The piano creates sound through the mechanical action of hammers striking strings when the keys are pressed. It does not require electricity since it is acoustically designed and relies on physical mechanics to produce its sound. A steamer, on the other hand, might initially seem like an item that needs electricity, but it also refers to cooking equipment that can produce a whistling sound using steam pressure, without necessarily relying on electrical power.
In contrast, an electric piano and a hairdryer both require electricity to function and produce sound. An electric piano needs to be powered to produce digital sounds or to amplify the sound through its speakers, while a hairdryer's motor and heat elements need electrical power to operate, thus creating noise and heat.