What device is worn in the external acoustic meatus to amplify sound waves for mild to moderate hearing loss?

The device that is worn in the external acoustic meatus to amplify sound waves for individuals experiencing mild to moderate hearing loss is the hearing aid. Hearing aids are specifically designed to enhance the sounds around the user by amplifying sound waves that might otherwise be too faint for a person with hearing loss to hear clearly. They typically consist of a microphone to pick up sounds, an amplifier to boost the sounds, and a speaker that delivers the amplified sound directly into the ear.

In contrast, a cochlear implant is an electronic device that is surgically implanted into the inner ear, designed for individuals with more profound hearing loss who do not benefit from hearing aids. An audiometer is a device used to measure hearing acuity and is not worn by the patient; it’s used by professionals to assess hearing ability. The FM system is a type of assistive listening device that uses radio signals to transmit sound from a source directly to the listener's hearing aid or headphone and is generally employed in specific environments like classrooms rather than being worn in the ear like a hearing aid.