What was the purpose behind the personification of certain elements in The Wind Rises? In The Wind Rises, certain elements of the story are personified. From the beginning, we see an earthquake and fire, both of which are given very humanlike sounds, as well as being shown very artisicially (like the ground moving in waves instead of just shaking). Later, the planes in the movie are personified as well, their components and demonstrations being given very humanesque and biological sounds.



As Jiro and Honjo look around a plane in flight, an engine makes very gurgly sounds which are distinctly biological and not mechanical. Other planes do this as well, even in a scene which shows one of Jiro's designs as a conceptualization.

Obviously, the movie is very plane-centric and so the personification of the planes makes sense (to bring them to life). However, these other lifelike elements did not seem to fit into the more serious setting of this movie, compared to a movie like Ponyo.

What is the purpose of bringing these elements "to life" in The Wind Rises? And why was it these elements that were chosen?
The following is more an interpretation of the film, rather than a solid source of undeniable truth. Because of this, there is unfortunately a lack of sources.
I believe Hayao Miyazaki could have insisted on this feature. @krazer's comment on your questions backs this up:

Geoffrey Wexler, Studio Ghibli's &quot;Chief Gaijin&quot; who represented the company at the screening at the Toronto International Film Festival  [...]  answered an interesting fact about the sound production. He said Miyazaki wanted to do all the sound effects himself, but the staff denied him because he’s already too busy with all the other duties so someone else had to do it all.
He also let it be known that the movie has Mono sound, which apparently no one ever believes but that's another thing Miyazaki wanted and won out on.

Miyazaki mentions in an interview that he has always wanted to make an anime about planes - and being his last movie before retirement, this was probably a very personal film.
Miyazaki is a plane fanatic, although not a plane otaku, as he emphasizes in the documentary Kingdom of Dreams and Madness. In the documentary, you can see him playing with a model plane and making up his own sound effects. His autobiographies Starting Point and Turning Point feature planes as a secondary interest to anime too.

I imagine Miyazaki wanted to create The Wind Rises with a certain element of nostaliga and insight into the appeal of aeroplanes for himself, and other plane fans.
The film is somewhat about the beauty of planes and their unfortunate setting. Caproni appears in Jiro's dreams speaking of their wonder, despite humanity's ill use of them.
In this vein, I think Miyazaki wanted to show audiences the splutterings, whirrings and ka-puts that make the machines beautiful for him, even if they didn't sit right with the tone of the film.