Amplitude		Wave changes type (like longitudinal turning into shear) when it hits an angle boundary.
Angle beam		Main Bang
Attenuation		only pay attention to echoes in this area of the timeline
Critical angle		Predictable sound beam after the near field
Beam spread		The distance the probe moves in between Scan paths, like mowing a lawn
Dead zone		Sound gets weaker as it travels farther
Focal Law		Sound particles move forward and backward (same direction as wave).
Diffraction		The spreading or bending of waves as they pass through an aperture or around the edge of a barrier.
Gate		How hard it is for sound to move through a material
Impedance		Shallow area just under the surface where flaws can’t be seen.
Initial Pulse		The entire set of hardware and software parameters affecting the acoustic sensitivity field of a phased array search unit,
Far Fieald		Smallest signal that will produce a visable response "how well the machine can “hear” tiny flaws
Near Field		A control for minimizing or eliminating low-amplitude signals "mute for background noise"
Longitudinal wave		The time sound takes to travel through a part from probe to reflector and back
Range		Wave motion where particle movement is perpendicular to the direction the wave is traveling.
Mode Convertion		Sound sent into the part at an angle (not straight in)
Reject		Irregular sound beam before far fireld
Resolution		The entry angle where one type of sound wave stops existing inside the part.
Scanning Index		How tall the signal spike is on the screen (signal strength)
Time of flight		How far "deep" your screen is set to look
Sensitivity		The angle-beam sound path in a material that starts at the probe, reflects off the back wall, comes back up to the top surface "V"
Shear Wave		The sound beam fans out wider as it goes deeper.
Vee Path		The ability of UT equipment to separate two discontinuities that are too close