A masking procedure has been developed to rank apartment floor‐ceiling systems in order of their resistance to the transmitted sound of footfalls. Results obtained subjectively show that the current international standard for rating impact noise transmission using a tapping machine incorrectly ranks some wood‐framed floor‐ceiling systems. When the described procedure is used to mask tapping machine noise, the floors are also incorrectly ranked. This inadequacy continued even though low frequencies, below the 89‐Hz cutoff of the 100‐Hz 1/3 octave, were included in the masking procedure. Because the masking procedure described is subjective, the problems associated with the development of an objective test are also discussed. A simple objective test method is suggested for future development.