I would bet you that if you operated both fans in an perfectly empty, very quiet room with a human standing next to them, one at a time, the human-perceived level of noise annoyance from the 140 would be much less due to its lower pitch.
Additionally if you use a variable fan controller to reduce the rpm on the 140 to a point where its cfm or cubic meters/hour of airflow is exactly equal to the 120, or 5-10% greater than the 120 at its default rpm, not only will its pitch be lower, but its objectively measured loudness on a decibel meter will also be less.
Additionally if you use a variable fan controller to reduce the rpm on the 140 to a point where its cfm or cubic meters/hour of airflow is exactly equal to the 120, or 5-10% greater than the 120 at its default rpm, not only will its pitch be lower, but its objectively measured loudness on a decibel meter will also be less.