All the speakers I have ever heard of are more than 1 ohm. Of course somebody "could" have a built a 1 ohm for a special circumstance.......but I doubt it.
Now do people parallel speakers and get the impedance too low?
Sure.
People also drive and drink.
In either case they don't know what they are doing.
Lowest impedance I have ever heard of is old Bose speakers that were 2 ohms. They may still be. Keep waiting for jaak to a sweep a septrum analyzer across one and tell us........
In any event the impedance of a non Bose auto speaker system is almost positively 4 ohms or greater, with a good liklelyhood that it is 8 ohms.
Homer