Here are explanations of some acoustic terms, the list is by no means exhaustive but these are some of the more common terms.

Acoustic Measurements

• Background Noise
  Noise break-in
  Internal noise: heating, air-conditioning, lighting etc.
• Reverberation Time
  The reverberation time of the room is critical to speech intelligibility and musical clarity. Reverberation time (RT60) is the time, measured in seconds, for the average sound in a room to decrease by 60 decibels after the sound source stops generating sound.
• Reflections
  Reflections are sound waves that are bounced off reflective surfaces and when mixed with the direct sound can cause deterioration in the intelligibility of the sound (destructive). By plotting the time arrival of reflections we can calculate where they are coming from. They may also be used to distribute sound in a large space allowing listeners further away from the source to receive amplified sound (constructive).
• Standing Waves
  Also called room modes, these are frequencies at which the room is naturally resonant. Room modes are typically set up at the lower frequencies and are exacerbated by parallel surfaces. Room modes will make the bass response seem muddy and a listener would hear uneven base response as the long wavelength sound waves add to or cancel each other out. Room modes can be broken up by suitably placed absorptive materials.
• Flutter Echoes
  These are produced by sound bouncing between parallel surfaces, with unpleasant audible results. A flutter echo is usually initiated by a percussive sound.

Electro-Acoustic Measurements

• Loudspeaker choice and locations
  There are many options in loudspeaker type and their dispersion characteristics. The choice is critically linked to the results of the above measurements.
• Loudspeaker time alignment
  Electricity travels approximately a million times faster than sound in air. The result can cause problems when you hear the loudspeaker before you hear the talker or other loudspeakers!
• Gain-before-Feedback
  The familiar sound of feedback is avoidable. Let us calculate the potential and advise you how to avoid it.
• Speech Intelligibility
  This is the big test. It measures how successful the overall system design has been in the given acoustic environment.