Question On Ports And Cones Cancellation and Relative Size

[kelticwizard]

Speaker A, an 8 inch speaker of 32 sq in cone area, is in a Transmission Line Enclosure. At 300 Hz it's SPL @ 1M/1W is 90 dB.

The port, (terminus) of that Transmission Line has an area of 96 sq in-three times the cone area. It too has an SPL of 90 dB @1W/1M. Assume distance between port and terminus are negligible.

How can I find the summed output in SPL of cone and terminus at 300 Hz if:

A) Both cone and terminus are in phase?

B) The terminus is 90 deg out of phase with the cone?

C) The terminus is 180 degree out of phase with the cone?

I'm trying to find the relationship between cone size, port size and phase. If anyone knows an equation, that too would be greatly appreciated.