Voice Biometrics Basics – Metrics

There are several metrics used to measure the success of a voice biometrics system:

• Enrollment rate – % of authorized users who successfully enrolled (i.e., “base” voiceprint captured)
• Verification rate - % of authorized users who are successfully verified (i.e., “sample” voice print captured and matched against “base” voiceprint)
• False acceptance rate (FAR) - % of unauthorized users who are accepted by the system. Also known as false positive or type I error.
• False rejection rate (FRR) - % of authorized users who are rejected by the system. Also known as false negative or type II error.
• Crossover error rate (CER) – point of intersection when FAR and FRR are plotted against each other (i.e., FAR = FRR). In general, the lower the CER the better.

It’s a fine art to tune a voice biometrics system to achieve simultaneously low FARs (i.e., keeping the unauthorized folks out) and low FRRs (letting the authorized folks in).