Apodization, or Exponential Multiplication, or Window Processing

The signal-to-noise ratio (S/N) of an NMR signal can be improved by increasing the number of scans, but this rapidly leads to inconveniently long experiment times. Another approach is to multiply the free-induction decay (FID) by a decreasing exponential function which mathematically suppresses the noise at long times. Other forms of apodization functions can be used to improve resolution or lineshape.