This may be less critical in the high-security environments that biometrics are known for protecting, but it can be a crucial factor with some applications. For example, a major entertainment company has replaced tickets with hand-geometry devices because of this technology's very low FRR and its general acceptance by the population. Administrators have to balance false acceptances versus false rejects, the possibility of fraud versus user convenience. And some systems today still require periodic adjustment to assure correct reading. Likewise, voice-recognition systems can require considerable user training, especially when used at more secure sensitivity settings.
Some populations have difficulty using biometric devices.
People with light ridge definition in their fingers may have difficulty using fingerprint-recognition systems. There also are substantial physical differences based on age, gender and ethnicity. Face recognition may not be practical in industrial and medical environments where hoods or masks are required. The security of the connectivity between the device and host, as well as the host and any back-end verification engine, is crucial to avoid wire snooping and playback attacks. Many devices that use standard cameras, microphones and other equipment should encrypt or sign packets on the wire.