Other ways to customize your hearing aids exist, including:

• Directional microphones. These microphones pick up sounds coming from in front of you better than coming from behind or beside you. This technology improves your ability to hear when you're in an environment with a lot of background noise. Typically you'll have both a regular microphone and a directional microphone, so you can switch between the two types. This might require a larger hearing aid to accommodate the two microphones.
• Telephone adapters. This technology, also referred to as telecoils, makes it easier to hear when talking on the telephone. Flipping a switch directs your hearing aid to eliminate sounds from your environment and pick up sounds from the telephone only. Keep in mind that this technology works only with telephones designated as hearing aid compatible — most cordless phones and cell phones aren't.

(by sicologic.com)