There are a number of different ALDs available with the most commonly chosen type being Personal Amplifiers.
Personal Amplifiers can be supplied with a variety of microphones that can be placed near the sound source, not just pointed from a distance. They can also be supplied with a variety of earpieces, not just headphones.
Neckloops or Silhouette Couplers can also be used to work with hearing aids or implants switched to 'Telecoil'.
Some Personal Amplifiers have a detachable microphone that can be positioned nearer to the sound source and can deliver quality sound from a distance significantly better than a standard hearing aid. Personal Amplifiers that have provision for an external microphone can also use special purpose microphones (e.g. conference microphones) to further enhance their performance. The microphones used with most Personal Amplifiers have larger diaphragms and therefore a greater pickup range - both in frequency and distance.
Some ALDs are designed primarily for use with TV. These devices may also use a microphone to pick up the sound from the TV. For systems that use this approach, there is also a benefit that the device can be used as a conversation aid as anyone needing assistance with the TV will also commonly need assistance with conversational speech.
Some TV Devices can be supplied with a variety of earpieces, not just headphones. Most can also use neckloops for use with hearing aids or implants that have a telecoil function and there are some that are just personal or small area loop systems for use with the telecoil in an aid or implant.
The ALD may also be connected directly to the TV audio out sockets. However, there are increasing complications with the direct connection approach as more TVs are now delivering High Definition Video and using different audio out formats (optical, HDMI, or digital coaxial).
For HD Video televisions there is a noticeable delay between the picture on the screen and the sound (as broadcast). This delay difference is compensated for internally by the TV circuitry so that the sound from the TV speaker is delayed to keep in step with the picture; however, the direct connection for audio out is not delayed.
Compatibility between the direct connection format on the TV Device (commonly RCA inputs) and the TV audio out connections (HDMI, Optical, Digital Coaxial) can also be problematic but there are converters available.
The delay and connectivity problems are not an issue if you use a TV Device with a microphone.