A) hearing is the most important sense shown in the passage. This is because throughout the passage allusions to sounds are made, such as the silence interrupted by the sound of the spoon scraping the pan and the low and intertwined voices of people talking. This shows that the narrator's hearing was the most active sense at the moment.
b) The kroo-kroo-kroo of the metal spoon in the pan is described as intrusive, it means that this sound is breaking the balance of the environment and is exposed uncontrollably. This sound contrasts the image of silence that the narrator exposes right at the beginning of the passage. This shows the effect that the silence was so uncomfortable that it made the narrator to pay attention to anything around him in an anxious and eager way.