If an extra pane of glass is put in with a large gap between it and the other panes, that should reduce the external noise. However, if trickle vents are put in for ventilation, some noise will get in as well.
I think you're right - there really isn't a simple way to have ventilation and noise reduction at the same time, so the simple solution really is to avoid trickle vents, and just open the window for a short period of time - this also gives you a chance to smugly appreciate the 'turning off' of external sound as you close the window.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local