Question

What is studied in helioseismology?

Answer 1

"Helioseismology" is a technique used to study the interior of the sun through its oscillations.

Explanation:

Helioseismology, a term coined by Douglas Gough, is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surface.

Pictures and descriptions here:
https://solarscience.msfc.nasa.gov/Helioseismology.shtml