Low noise turbine for geared gas turbine engine

A turbofan gas turbine engine, comprising:

• a fan section including a fan having a plurality of fan blades, and including an outer housing surrounding the fan to define a bypass duct;
• a turbine section including a fan drive turbine and a second turbine;
• a compressor section driven by the turbine section, the compressor section including a first compressor and a second compressor;
• a geared architecture driven by the fan drive turbine;
• and
• wherein the fan is driven by the fan drive turbine via the geared architecture, and the second turbine drives the second compressor;
• wherein at least one stage of the turbine section includes an array of rotatable blades and an array of vanes, and the array of vanes of the at least one stage are immediately upstream or downstream from the array of blades;
• wherein a ratio of the number of vanes to the number of blades of the at least one stage is greater than or equal to 1.55;
• wherein a mechanical tip rotational Mach number of the array of blades is greater than or equal to 0.5 at an approach speed, the approach speed taken at an approach certification point as defined in Part 36 of the Federal Airworthiness Regulation;
• and
• wherein the gas turbine engine is rated to produce 15,000 pounds of thrust or more.