oímos el tráfico de coches desde casa

Question

This is very poorly worded. Oír means to hear, NOT can hear NOR is able to hear, so why have you asked can hear in the question?

Now I don't know whether to use poder (conjugated) + oír or oír because I don't know whether you are asking me can hear or hear.

Accepted Answer

Hola Peter
We always use the most natural translations in English even when this is not literal. 
Using the present of the verb instead of "can..." in English would sound a bit odd in some sentences:

Oímos el tráfico de coches desde casa.
We hear?? the traffic from home.
We can hear the traffic from home. (more natural)

In Spanish though, we can use the main verb in the present without using poder and would still imply the same (the ability to hear, not just to hear)
This is common with some perception verbs. We have a specific lesson about this usage. You can have a look here. 
I hope it helps.
Inma