Apart from the obvious things that have already been mentioned, such as the fans being closer to the pitch and there being terracing around the corners at Wilderspool, there are some other major factors as to why the atmosphere was more intimidating.
Acoustically Wilderspool was much better at retaining noise. I think this comes down to the design of the rusty old roofs above the Fletcher and Railway ends. They were shaped in a sort of A Frame, perfectly demonstrated by these pictures:
www.worldstadia.com/ws/show-page ... nuData=924
farm3.static.flickr.com/2360/243 ... 24.jpg?v=0
This helped to trap the terrace sounds and have an amplifying effect which would reverberate around despite crowd size being smaller. The roofs at the HJ are straight and slant slightly upwards and outwards, which means that not as much of the sound is retained and a lot “escapes”.
Another major difference is between the two standing terrace designs at the HJ. The South Stand has an enormous gap between the back row of terracing and the roof which means that most of the sound just dissipates, as shown in this picture:
www.worldstadia.com/gallery/Engl ... 5/1464.php
The West Stand’s roof is much closer to the back row of terracing which means that more sound is trapped and that’s why the away fans always sound much louder than the home fans at the HJ. Plus the slightly smaller capacity of the West means that the fans are more tightly packed together behind the sticks, which intensifies the singing, etc, rather that it being diluted across several clusters in the South Stand.
For me the solution to this is simple, the home fans should have the West Stand and the South should be allocated to away supporters, although obviously home supporters could still go in there in great numbers if they wished, since not many visiting sides would come close to filling the circa 4,000 capacity.
Another option would be to introduce a second tier into the South Stand (which is presumably why the roof was designed so high), which would help the noise to reverberate around, but how realistic that is is anyone’s guess.