Which of the following statements about hearing aids is true?

Hearing aids can indeed utilize different types of microphones, which is key to their functionality and performance. Different microphone designs allow for various sound processing capabilities, including the ability to enhance speech sounds while minimizing background noises. For instance, some hearing aids may feature directional microphones that focus on sounds coming from a specific direction, which can help users hear better in noisy environments. Other microphones might use omnidirectional configurations, capturing sound from all around to create a more natural hearing experience.

The other options do not accurately reflect the diversity and specifications of hearing aids. For example, hearing aids come in various sizes and shapes tailored to different needs and preferences, not all requiring a prescription as some basic models can be purchased over-the-counter. Additionally, while many hearing aids are designed to reduce background noise, none can completely eliminate it, as complete noise cancellation can hinder the perception of important sounds in a user's environment.