It's really hard from your description to know just how load your voice is and the surrounding traffic.
I can only say that we have benchmarked ZenFone 6 against other phones in loud environments and even though it wasn't the best performing phone in our round up, it also wasn't the worst. We have acceptable result and the hardware can't be pushed any further.
If you sit in a car with windows closed, it should be fine but if you're in a rickshaw with cars and motorcycles honking next to you so you need to shout to make yourself heard, well then our phone isn't for you. Many similar phone will also fail at this task as designs with pop up cameras and similar put a limitation on how big earpiece you can fit inside.
