... which defense media outlet is this?
It is true that the 094 is quite a bit smaller than the other larger SSBNs of other more established SSBNs (especially the USN and Russian Navy's), the 093's measured dimensions and hull diameter from places like google earth, indicates that 093 does not seem to be that much smaller than other SSNs. Of course, 093 and other Chinese nuclear submarines uses a double hull design, meaning the actual pressure hull which is able to accommodate various noise dampening systems are less than single hull submarines... but Russian SSNs are also double hulled and the latest Russian SSN designs are also considered to be quite competitive.
So I am quite curious as to what this source means when it refers to "1/3 smaller" -- because the 093's overall hull diameter is definitely not 1/3 smaller, and if they're talking about the pressure hull, then I'm not sure how they know how large 093's pressure hull actually is, and also how they can compare that to other SSNs with double hull designs such as that of Russia, to ultimately make the 1/3 smaller statement.
Also, the pressure hull has nothing to do with 094's hump, because they could easily have developed a larger outer hull to remove the hump if they really wanted to but it would not be very useful. Russian SSBNs such as the "Typhoon" class SSBN is also a very unique double hull class, yet it still has no hump, so it isn't correct to necessarily assume that a single hull design means one will have a hump-less SSBN.
It may be part of the reason, but it probably isn't as major as one thinks..
UK and French SSNs and SSBNs are quite a bit smaller than their Russian and US counterparts, yet are considered to be quite competitive.
It is probably more important to have good manufacturing, and good noise dampening mechanisms in place, than simply having greater internal volume.
