Sometimes waves don't travel in a straight line, even if their speed does not change (as in the case of refraction). For example, you can hear the conversation in the next room even though you cannot ...Sometimes waves don't travel in a straight line, even if their speed does not change (as in the case of refraction). For example, you can hear the conversation in the next room even though you cannot see the source. This is because sound waves undergo diffraction, bending as they go through the doorway between the two rooms.
