parshat Bo #1: How far did Pharaoh's voice carry?

In Shemot 12:31, Pharaoh calls to Moshe and Aaron and tells them that they may lead the Israelites to serve Hashem:

לא וַיִּקְרָא לְמֹשֶׁה וּלְאַהֲרֹן לַיְלָה, וַיֹּאמֶר קוּמוּ צְּאוּ מִתּוֹךְ עַמִּי--גַּם-אַתֶּם, גַּם-בְּנֵי יִשְׂרָאֵל; וּלְכוּ עִבְדוּ אֶת-ה, כְּדַבֶּרְכֶם.

31 And he called for Moses and Aaron by night and said: 'Rise up, get you forth from among my people, both ye and the children of Israel; and go, serve the LORD, as ye have said.

One midrash states that Pharaoh called to Moshe and Aaron while he was still in his palace at one end of Egypt, and they were at the other end of Egypt, yet his voice carried this great distance.

The impetus is that we see Pharaoh (in the previous pasuk) awaking in the middle of the night in his palace, and we know that Moshe is with the Israelites, so how was the message carried?

ל וַיָּקָם פַּרְעֹה לַיְלָה, הוּא וְכָל-עֲבָדָיו וְכָל-מִצְרַיִם, וַתְּהִי צְעָקָה גְדֹלָה, בְּמִצְרָיִם: כִּי-אֵין בַּיִת, אֲשֶׁר אֵין-שָׁם מֵת.

30 And Pharaoh rose up in the night, he, and all his servants, and all the Egyptians; and there was a great cry in Egypt; for there was not a house where there was not one dead.

Further, we do not have a description of Moshe and Aaron appearing before him - just the message. And more, in Shemot 10:28-29, we have the following exchange:

כח וַיֹּאמֶר-לוֹ פַרְעֹה, לֵךְ מֵעָלָי; הִשָּׁמֶר לְךָ, אַל-תֹּסֶף רְאוֹת פָּנַי--כִּי בְּיוֹם רְאֹתְךָ פָנַי, תָּמוּת.	28 And Pharaoh said unto him: 'Get thee from me, take heed to thyself, see my face no more; for in the day thou seest my face thou shalt die.'
כט וַיֹּאמֶר מֹשֶׁה, כֵּן דִּבַּרְתָּ: לֹא-אֹסִף עוֹד, רְאוֹת פָּנֶיךָ.	29 And Moses said: 'Thou hast spoken well; I will see thy face again no more.' {P}

So Moshe should not see Pharaoh any more, or at least have an audience with him in court. (The same two details likely cause the midrash which has Pharaoh seeks out Moshe and Aaron rather than the reverse.)

So, וַיִּקְרָא לְמֹשֶׁה וּלְאַהֲרֹן is understood as "he called to" rather than "he called for."

However, the best bit is the direct source (not explicitly mentioned in the midrash, but it seems clear to me) for Pharaoh's voice carrying throughout Egypt: The juxtoposition of the following two phrases:

ל וַיָּקָם פַּרְעֹה לַיְלָה, הוּא וְכָל-עֲבָדָיו וְכָל-מִצְרַיִם, וַתְּהִי צְעָקָה גְדֹלָה, בְּמִצְרָיִם: כִּי-אֵין בַּיִת, אֲשֶׁר אֵין-שָׁם מֵת.	30 And Pharaoh rose up in the night, he, and all his servants, and all the Egyptians; and there was a great cry in Egypt; for there was not a house where there was not one dead.
לא וַיִּקְרָא לְמֹשֶׁה וּלְאַהֲרֹן לַיְלָה, וַיֹּאמֶר קוּמוּ צְּאוּ מִתּוֹךְ עַמִּי--גַּם-אַתֶּם, גַּם-בְּנֵי יִשְׂרָאֵל; וּלְכוּ עִבְדוּ אֶת-ה, כְּדַבֶּרְכֶם.	31 And he called for [/to] Moses and Aaron by night and said: 'Rise up, get you forth from among my people, both ye and the children of Israel; and go, serve the LORD, as ye have said.