[cyphar]

The argument is that if a human brain can recognise speech accurately without needing your hypotehtical ultrasonic overtones, why would a computer need them? Not to mention that most mid-range microphones won't pick up such overtones anyway. There isn't a flaw in their logic, you're just arguing that there might be more information that a computer can use -- but the fact that we don't need it leads to the conclusion that a computer doesn't need it either.