Bill, speakers are electro-mechanical by design, however, there are no moving components whose properties actually that stretch or contract. The only moving components is the cone, which is corrugated near the base and rim so it can move in and out, but it does not stretch. It is often made of a special type of paper that does not stretch by design, thus preventing changes in frequency response over years of usage, and changes in environmental conditions, temperature, humidity, etc... The spider, which is nothing more than a series of wires that form a magnet near the base of the cone, which reacts to the permanent magnet when changes in electrical current is detected. Obviously, the wires do not change in shape, size or elasticity.

Distortion in speakers usually is the result of either the speaker being overdriven, or something that has ripped loose either from being overdriven, or physical damage, which would cause the cone to rattle against a tear in the cone material. When I was a youngster, we frequently repaired torn speaker cones using nothing more than a piece of old tee shirt glued in place over the torn spot with rubber cement - it worked great.

Graham Crosby, an old friend, who also resides on the English Riviera, spent much of his life designing speakers. Maybe he can jump in and shed some additional information on this subject, which definitely IS a myth!

All the best,

Gary

Gary