A personal amplifier contains a microphone that picks up sound and an amplifier to make the sound louder. It usually consists of a box slightly larger than a matchbox with the components enclosed. A general rule of thumb is the larger the box, the more powerful the device. The box is usually connected to ear-bud headphones through which the amplified sound is heard. They can be useful for people who have difficulty wearing or managing conventional hearing aids or who are unable to tolerate anything inside the ear canal. They are also a good option when the device is managed by another person as the controls are large and headphones are easy to place over the ears. Usually a personal amplifier will have a volume control that can be adjusted by the wearer – but unlike hearing aids they are not set up to match the individual’s specific hearing loss. Often personal amplifiers can be plugged directly into other devices such as the television. They can be a good solution if a simple, easy to manage device is required. They are usually fitted instead of hearing aids but can also be used with hearing aids via the telecoil.