comments:
Any microphone capable of an omnidirectional (hears from every direction) pickup pattern will do well for this. A boundary microphone, also sometimes known as a PZM, is ideal for this application. Make sure it's omnidirectional (and not cardioid or variants). Here's an example: https://www.amazon.com/Audio-Technica-ATR4697-USB-Omnidirectional-Condenser-Microphone/dp/B082BC34TS/ref=sr_1_7 (A cardioid microphone will hear whichever speaker it's pointed at very well, but will reject sounds from behind it and to its sides. This would be ideal if it were just one person speaking in a noisy room.) I would place a PZM mic like this directly on the table (if there is one) in front of the people speaking. There's no microphone that will reject traffic & AC noises, so the further the people speaking can be placed from these noises sources, and the closer the microphone to the people, the better. In a pinch, you can use noise reduction software after the fact to attenuate noise by having the software "learn" what noise is. iZotope RX Spectral De-Noise is one of the best tools for this. Not cheap, however. Probably could farm out the de-noising via fiverr or similar, if there aren't privacy concerns around the speech.