Low noise turbine for gas turbine engine

An aircraft system comprising:

• an aircraft;
• and
• a gas turbine engine coupled to the aircraft, wherein the gas turbine engine comprises:
• propulsor means for providing propulsion;
• first compression means for compressing airflow from the propulsor means;
• second compression means for compressing airflow from the first compression means;
• reduction means for reducing a rotational speed of an output that drives the propulsor means relative to an input, wherein the reduction means establishes a reduction ratio of greater than 2.5:1;
• first expansion means for driving the second compression means in response to expanding airflow from the second compression means;
• second expansion means for driving the input of the reduction means in response to expanding airflow from the first expansion means;
• wherein the second expansion means includes a number of turbine blades in each of a plurality of rows, which operate at least some of the time at a rotational speed, and the number of turbine blades and the rotational speed being such that the following formula holds true for at least one row of the plurality of rows:
• 5500 Hz≤(number of blades×speed)/60 sec≤10000 Hz;
• wherein the rotational speed is an approach speed in revolutions per minute taken at an approach certification point as defined in Part 36 of the Federal Airworthiness Regulations;
• and
• wherein the gas turbine engine is rated to produce 15,000 pounds of thrust or more.