Exposure to low-frequency sound. Infrasound refers to sound frequencies below the audibility range of the human ear. A study of the physiological effects of infrasound was published in the Journal of Low Frequency Noise, Vibration and Active Control (Mar.

2004). In the experiment, one group of five university students (Group A) was exposed to infrasound at 4 hertz and 120 decibels for 1 hour, and a second group

 LO4 of five students (Group B) was exposed to infrasound at 2 hertz and 110 decibels, also for 1 hour. The heart rate (beats/minute) of each student was measured both before and after exposure. The experimental data are provided in the accompanying table. To determine the impact of infrasound, the researchers compared the mean heart rate before exposure to the mean heart rate after exposure.
Group A Students Before Exposure After Exposure Group B Students Before Exposure After Exposure A1 70 70 B1 73 79 A2 69 80 B2 68 60 A3 76 84 B3 61 69 A4 77 86 B4 72 77 A5 64 76 B5 61 66 Based on Qibai, C. Y. H., and Shi, H. “An investigation on the physiological and psychological effects of infrasound on persons.” Journal of Low Frequency Noise, Vibration and Active Control, Vol. 23, No. 1, March 2004 (Tables I–IV).

a. Analyze the data on Group A students with an ANOVA for a randomized block design. Conduct the ANOVA test of interest with a = .05.

b. Repeat part a for Group B students.

c. Now analyze the data via a paired difference t-test.
Show that, for both groups of students, the results are equivalent to the randomized block ANOVA.