A hearing aid is a device used to help the hard-of-hearinghear sounds better. In the past, a funnel-like amplification cone, called an "ear trumpet" or "ear horn", was used. Now, however, the most common style is a small electronic device that fits into the wearer's ear. The first variety of this device had a rectangularbattery pack connected by a thin wire, intended to be held in a pocket. During the mid- to late 20th century, this type of power storage was replaced by a more inconspicuous sort in models in which small, circular batteries were placed in the inserted unit itself.
