Mean and median spectra of all 220 LAEs described in Sect. 2.1 shown in black and blue with the error displayed via gray and light-blue shaded areas, respectively. The vertical lines indicate the rest-frame wavelengths of some of the main spectral features: nebular emission lines (purple), ISM absorption (orange), and fine-structure transitions (green). The bottom panels show the S/N per pixel (gray and cyan curves for mean and median spectra, respectively) with the dotted red horizontal line indicating S/N = 3.