The unit of the HRV data is second.

First row contains the header.

First column is the HRV data of soprano singer #1.
Second column is the HRV data of soprano singer #2.
Third column is the HRV data of soprano singer #3.
Fourth column is the HRV data of soprano singer #4.
Fifth column is the HRV data of soprano singer #5.

Sixth column is the HRV data of bass singer #1.
Seventh column is the HRV data of bass singer #2.
Eighth column is the HRV data of bass singer #3.
Ninth column is the HRV data of bass singer #4.

