Bingo, they are called room modes: https://en.wikipedia.org/wiki/Room_modes?wprov=sfla1 https://en.wikipedia.org/wiki/Room_modes?wprov=sfla1 Their influence c

Bingo, they are called room modes: https://en.wikipedia.org/wiki/Room_modes?wprov=sfla1 https://en.wikipedia.org/wiki/Room_modes?wprov=sfla1 Their influence can be be diminshed with absorbers, construction of a room without parallel walls or so big that they can't be heard (eg Concert halls)