AAR	Association of American Railroads
AE	Acoustic Emission
AUC	Area Under the (ROC) Curve
BH	Blind Hole(s) (defect label)
BPR	Band Power Ratio
DAQ	Data Acquisition system
EMAT	Electromagnetic Acoustic Transducer
EEG	Electroencephalography
FL	Flange Damage (defect label)
FRA	Federal Railroad Administration
H	Healthy (class label)
ICP®	Integrated Circuit Piezoelectric (constant-current sensor interface)
KDE	Kernel Density Estimation
LL	Line Length (burst detection feature)
NT	Notch/Notches (defect label)
PSD	Power Spectral Density
RCF	Rolling Contact Fatigue
ROC	Receiver Operating Characteristic
RMS	Root-Mean-Square
SNR	Signal-to-Noise Ratio
SP	Spalls (defect label)
SRC	Shattered Rim Crack
STD	Standard Deviation
STE	Short-Time Energy (burst detection feature)
SVM	Support Vector Machine
UAE	Ultrasonic Acoustic Emission
UT	Ultrasonic Testing
VSR	Vertical Split Rim
CI	Confidence Interval