Laboratory impact noise measurements below 50 Hz

It has been well established that impact noise at low frequencies is very important to occupant reaction, typically in the 50-100 Hz third octave bands. Some researchers have presented data that frequencies below 50 Hz as measured in field testing are important to subjective reaction. Such frequencies are not generally considered meaningful in laboratory testing due to increased uncertainty and questionable reproducibility. However, the authors have previously shown (LoVerde and Dong, Laboratory Measurement of Low-Frequency Impact Sound, ICSV 2018) that it is possible to extract useful comparative data at low frequencies, despite the increased uncertainties. The authors have extended the analysis to include impact sound levels below 50 Hz for a series of common floor-ceiling assemblies. Results are presented comparing the sound levels above and below 50 Hz, discussing the effect of changes to floor-ceiling assemblies below 50 Hz and comparing it to results from field testing.