This document discusses speaker recognition techniques and applications. It provides an overview of common feature extraction methods for speaker recognition systems such as Linear Predictive Coding (LPC), Perceptual Linear Predictive Coefficients (PLPC), Mel Frequency Cepstral Coefficients (MFCC), and Gamma Tone Frequency Cepstral Coefficients (GFCC). It compares these techniques and finds that MFCC and PLPC are most often used due to being derived from models of human auditory processing. GFCC has benefits of higher frequency resolution and noise robustness compared to MFCC. Speaker recognition has applications in security systems for access control.