Garden wall acoustics….block face down or double skin with cavity/insulation better?

[slittle36]

Hello. I’ve been searching for ages but am still stumped, although enjoying the research, so thought I’d ask here.
Our sloped garden runs along side an A road, between about 3m and 12m above the road. I’m going to be constructing a block wall to replace the current hedge, but would love to know anyone’s thoughts on whether laying blocks face down to create a solid 21cm wide wall or double skin with cavity, with or without insulation (wondering about wall ties reducing the effectiveness) would be better for blocking/reflecting/absorbing the sound. They’re dense blocks, and will be rendered on the garden side for either option. It won’t be higher than 2m, which will be an effective shadow given the height above the road.

Thanks in advance.

 

[Deluks]

Sounds like a lot of work and money, have you looked into acoustic fencing as an alternative?

 

[Scally-Ho]

What about the type of fenced boundaries that airports use to deflect most of the noise skywards.

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