Further sound insulation through bookcases?

[Garald]

But what *is* the conclusion? That with 18cm of insulation, it is likely that almost all the noise is coming through the window, even though it has good noise-reduction properties (for a double-glazed window)?

[Mike]

10 hours ago, Garald said:

it is likely that almost all the noise is coming through the window

Probably. Not necessarily the glass, could be the frame or the way it's fitted, as previously mentioned.

[Adsibob]

On 06/04/2023 at 23:57, Garald said:

Say I can choose any material I want, as long as it's 1cm thick, uniformly so. What should I get?

SBx board. It has a honeycomb membrane within it which is filled with sand!

 

 Here’s a link:

 

https://soundstop.co.uk/products/sbx-10mm?gclid=Cj0KCQjwxMmhBhDJARIsANFGOSuUofF911Xb5-vuMPuTv5_ByxA80S3ltPhXskG_yBBuB7MLEeSr1ekaAu3eEALw_wcB

[Adsibob]

11 hours ago, Garald said:

even though it has good noise-reduction properties (for a double-glazed window)?

If it is a 38dB reducing window, that is not top spec. There are soundproof windows that will reduce by 40dB or even 41dB, though you might need to go to 3G to achieve 41dB.