What Is The Wiss And Parmelee Rating Factor?
Wiss and Parmelee also conducted research to refine the findings of Lenzen’s research. In particular, they attempted to quantify, in a more scientifically rigorous manner, human perception to transient floor motion.
They subjected 40 persons, standing on a vibrating platform, to transient vibration episodes with different combinations of frequency (2.5 to 25 Hz), peak displacements (0.0001 to 0.10 in), and damping (0.1 to 0.16, expressed as a ratio of critical).
After each episode, the subject was asked to rate the vibration on a scale of 1 to 5 with the following definitions: (1) imperceptible, (2) barely perceptible, (3) distinctly perceptible, (4) strongly perceptible, and (5) severe. Using regression analysis, an equation was perception ratings.
This equation is presented below. Wiss and Parmelee rating factor:
R= 5.08 (FA/ D^0.217)^0.265
R= response rating; 1= imperceptible; 2= barely perceptible; 3= distinctly perceptible; 4= strongly perceptible; 5= severe.
F= frequency of the vibration episode, Hz
A= maximum displacement amplitude, in
D= damping ratio, expressed as a ratio of critical
A graph of this subjective rating system is shown in Fig. 5.115. It should be noted that the lines represent a mean for that particular rating. The authors suggest that the boundaries for each rating lie halfway between the mean lines.
The boundaries defining R= 1 and R= 5 are not identified by the authors. These ratings are unbounded; therefore, a mean line cannot be computed.