An experience reducing toilet flushing noise reaching adjacent offices. Free

An office building was experiencing loud toilet flushing noise in offices adjacent to the toilets. The toilets were a 1.2 gallon per flush model. A study by others documented some maximum A‐weighted slow sound levels greater than 60 dB with most greater than 50 dB and recommended a limit of 40 dB. The building owner made changes including an improved wall on one of the seven affected floors and asked the author to repeat the measurements. Results were mostly in the range of 40 to 50. Sound levels within the rest rooms were greater than 80 dB, and within the toilet stall of the loudest toilet—96 dB. The sound peaked in the 2000 Hz octave. A wall on one floor was modified by adding a layer of damped gypsum with successful results. The remaining walls were then modified similarly. The resulting average level of four flushes was less than 40 dB in all offices though some individual flushes were slightly greater than 40 dB. It was evident that structural flanking was controlling the remaining sound reaching the offices.