How to record very low sound ?

I want to record very low sound. This sound can be heard by ear, so it is in the range of 20 Hz to 20,000 Hz , but i think it is more between 20 hz to 200 hz . The sound that i want to record is broadcasted , so it is broadcasted in plain air , like when you are sitting in a coffee shop , so you can hear it and you can hear other people voices , what i want is to be ableto record this sound that is broadcasted in plain over a very low frequency . i don't think that we can use a contact mic , so i was wondering what kind of microphone you think is capable of recording this voice , Or what kind of equipment can be used to do this job . SO basically what i want is for someone who has some knowledge in electronics and audio equipment to recomment a product for me to buy , this product must be able to record very low sound in the frequency specified above .