Mothers’ rooms (also referred to as lactation rooms) have become more prominent in workplaces in the United States in recent decades. Since the amendment of Fair Labor Standards Act in 2010, employers in the United States with more than 50 employees have been required to provide a non-restroom space for mothers to nurse or pump breast milk. Such spaces are often designed to offer privacy and comfort—however, little consideration has been given to the acoustical criteria that would be appropriate for these spaces. To inform the development of best practice criteria for sound isolation, a sample of different breast pump models from different manufacturers has been measured to estimate the range of sound power levels and spectral content associated with lactation pump noise. Comparisons are then made between pump noise levels and common workplace wall constructions to test the efficacy of published sound isolation criteria. Additional consideration is given to the unique usage of this space type in comparison to common adjacency types to propose a data-driven sound isolation criteria for mothers’ rooms. Results from this effort also aim to inform further work towards developing criteria for reverberation time and background noise levels in mothers’ rooms.