Mixing past and present in a narrative

[Lauranne]

I'm reading a book for probably grade-school age kids (an adaptation of Howl's Moving Castle), and I'm confused by how the sentence structure in the narrative keeps switching between past and present tenses. For example:

今日もソフィーは、仕事部屋で、帽子づくり。
町へ遊びにいく、お針子たちの、楽しげな声が、聞こえてきます。
「a bunch of dialogue」
ソフィーは、手をとめて、まどの向こうの荒地を、目あげました。

Which I'd take to mean, loosely:
Making hats in the workshop as usual, Sophie hears the happy voices of the seamstresses who are going to visit the city.
[A bunch of dialogue]
Sofie put down her work and looked out the window at the Waste.

Or:
だれかが、ソフィーのかたに、手をおきました。
美しい青年です。
青年は、指先ひとつで、兵士を追いはらってしまいました。

Someone put his hand on Sophie's shoulder.
It is a handsome young man.
He dispatched the soldiers with one finger.

The majority of the narrative is in the past tense, like it would be English. So can anybody explain to me what the present tense endings are doing on some of the sentences? Like why isn't it 聞こえてきました? Or 美しい青年でした?
Thanks.

 

[Toritoribe]

It's a common technique often used in novels. The present tense has an effect to make the scene alive (as if the readers were there).

 

[Lauranne]

Hmm, so basically I needn't worry about a specific grammatical effect on the individual sentence per se, and can just take it more as a "this sentence is setting the scene" signal? 'Kay, that makes good sense. Thank you.