(a) The "noise of Rome" alludes to the "voice of Esav," to whom was bequeathed the blessings of Olam ha'Zeh (Bereishis 27), and who voluntarily forfeited Olam ha'Ba to his brother Yakov. That is why the Gemara in the end of Makos seems to compare it to the "best of Olam ha'Zeh." This voice wants to "remove a person from the world [To Come]" by attracting him to the Midos of Ga'avah and Ta'avah (haughtiness and lustfulness). The "sound of the sun" which shuts out the voice of Esav is thus the same as the voice of Yakov (Bereishis 27:22) that serves to bring an end to the forces of Tum'ah and to bring the world to the time of the Mashiach.

This is all the same theme as we discussed in the Insights regarding the sound of the sun.

I later found that this same theme is described, in even more detail, in the amazing Sefer "Yalkut Yehoshua" (on Agados ha'Shas) by the Manostrishtsher Rebbe.

(b) The connection to the preceding Sugya is to show that a sound is not heard as well during the day as it is at night, and even so the voice of the Kohen Gadol was heard during the day.

In fact, the voice of the Kohen Gadol "which was heard until Yericho when he said 'Ana Hashem'" is also related to the point discussed above. That is, through his inspired arousal to Teshuvah when he did the Yom Kipur Avodah, the entire nation was aroused in turn to serve Hash-m. (The city of Yericho is a metaphor for the "heart" of the land of Israel, since it was the first place conquered when the Jews enterred the land, and it alludes to all of the inhabitants of Eretz Yisrael.)

M. Kornfeld