[votingprawn]

If you want to avoid doing the maths I think you can draw the problem out (assuming the world is a flat piece of paper and the source is located on the same piece of paper with you)

From the timings given you can work out the distance from location B and C to the wavefront when it hits point A (4 x 330 and 6 x 330). If you then draw a circle centered at point B with radius 1320m, and a circle centered C with radius 1980m, then there is only one circle you can draw that intersects point A, and is tangent with the circles drawn at B and C. The center of that circle is the source (with an appropriate radius of error for timing measurement and distance measurement between A, B, and C)

https://imgur.com/a/tqV0ToU

[te]

Epic comment and diagram, thanks. From this, how can we calculate bearing and distance from one of our locations to the source? Edit: I see that we can use multilateration suggested by parent-sibling comment if we just had distance to source (ie radius of unique tangent circle).