As a simple approach to 3-dimensional NMR spectroscopy a novel type of expt. is proposed in which the dimension is reduced from 3 to 2 by synchronous incrementation of evolution period t, and the mixing time tm parameters: tm = Kt1. Because of the concerted stretching of the pulse sequence, this expt. is referred to as accordion spectroscopy. The salient feature of the novel expt. is the accommodation of 2-dimensional information along a single time or frequency axis. In complete analogy to std. 2-dimensional exchange spectroscopy, the peak positions in an accordion spectrum characterize the origin (w1) and destination (w2) of the exchanging magnetization. The 3rd dimension (wm) is reflected in the lineshape along the w1, wm axis. These lineshapes correspond to Fourier transforms with respect to tm of the mixing functions aii(tm) and aij(tm), and contain all information relevant to the dynamic processes. These mixing functions can be retrieved from an accordion spectrum by a 3rd (reverse) Fourier transformation for any pair of sites i and j. [on SciFinder (R)]