Level mismatch obtained from the loudness balancing tests between headphone and loudspeaker presentation for three headphones and 14 subjects across two sites. Each smaller marker is the mean for one participant, each bigger marker the mean over all participants with the whisker indicating the standard deviation. The results are plotted as eardrum sound pressure level difference between headphone and loudspeaker presentation for the same perceived loudness. The x-axis denotes the presented stimulus and the figure is split into the two tested rooms. Each colour represents one specific headphone type.