The expression of envelope protons was coined in the early days of NMR analysis. It vividly describes how the spectra of most steroidal compounds look: their many aliphatic, nonoxygenated, unsubstituted methine and methylene hydrogens give rise to a myriad of resonances between ca ~0.8 and ~2.6 ppm ("the envelope") that exhibit complex splitting patterns due to the numerous possible J-coupling relationships in these molecules. While some resonances can stand out as un-or less-overlapped, "the envelope" is mostly assigned as a collection of multiplets, which sometimes get partially assigned via 2D 1 H, C correlation spectra. These assignment challenges vary by molecule. Interestingly, testosterone represents a relatively modest case of resonance overlap (Figure ), especially when the spectrum is acquired at 600 MHz or above. However, a more detailed evaluation reveals that the differentiation and specific nomenclature of resonances vs. peaks vs. lines is essential for both proper interpretation and qNMR work.