Question

Question #0b32c

Answer 1

It makes it richer, or ‘fuller’.

Explanation:

The resonance is a result of harmonics or overtones in the pipe or string. These are multiples of (or whole number ratios of) the fundamental wavelength caused by standing waves in/on the the vibrating column of air/string.

Much more detail can be found on the excellent hyperphysics website here

http://hyperphysics.phy-astr.gsu.edu/hbase/Music/aircol.html#c1

and here

http://hyperphysics.phy-astr.gsu.edu/hbase/Music/stringa.html#c2

See also comment by MetaPhysik below - very true!