...noisy outside that he couldn't down to read what they had...
settle down表示“定居,过安定的生活;平静下来,安下心来”。表后一种意思时to可用作不定式符号及介词,如settle down to write an article, settle down to one's work; get down to sth表示“开始认真对待”,如Let's get down to work.(我们开始工作吧。)本句中to read是动词不定式,因此不能用get down ...