In a multiple driver loudspeaker system, it is important that the time delay inherent in each driver and its associated crossover network be the same to preserve accurate transient (see WFTD archive transient) response. In other words, the high frequencies and low frequencies much reach the listener’s ear at the same time. A system which meets this criterion is said to be “time aligned.” One way to accomplish this is to place the tweeter further away from the listener than the woofer, and this is done in many speaker systems. Another way is to design the crossover network to add a suitable delay to the high frequency signal before it gets to the driver.
The phrase “time alignment” is also sometimes used in reference to adding delay to one or more microphones in a situation where more than one mic is being used on an instrument, and the mics are at different distances from the instrument. A good example of this is orchestral recording where several mics are employed at various distances to accurately capture the sound of the orchestra in the hall. The microphones closer to the orchestra are sometimes delayed to be more in “time” with microphones placed out in the hall.
“Time Alignment” was copyrighted as a trademark by a speaker manufacturer years ago and is no longer widely used as a generic term.