How was Moses able to speak to over 600,000 people at once? This is a followup question to the question about Jesus speaking to crowds of 5,000 people without audio installation.
The book of Exodus says that Israelites had 600,000 men of fighting age. And often it has paragraphs like this:

Exodus 35:4
Moses said to the whole Israelite community, &quot;This is what the LORD has commanded:

There are many, many more examples like this. Sometimes, when Moses says something, and then events happen that affect the whole community:

Numbers 16:31 (NIRV)
31 As soon as Moses finished speaking all of those words, what he had said came true. The ground under them broke open. 32 It opened its mouth. It swallowed up those men. In fact, it swallowed up everyone who lived in their houses. It swallowed all of Korah’s men. And it swallowed up everything they owned. 33 They went down into the grave alive. Everything they owned went down with them. The ground closed over them. They died. And so they disappeared from the community.

So, how was a community of at least 600,000 males able to hear Moses when he addressed them? That is 30-times more people than would fill Madison Square Garden.
Most commentators follow a common Jewish understanding that the Jewish leaders immediately relayed his words to their clans or households.


  Unto all Israel. It cannot be supposed that Moses spoke to the whole multitude of the people so as to be heard by them. Hence the Jewish interpreters say that he spoke to the elders of the people, who carried his words to the people at large. This is just; for what was thus mediately communicated to the people might be fairly described as spoken to them; and we find from other passages in the Pentateuch that the phrase, “the elders of Israel,” in the mind of the writer, was equivalent to “the congregation of Israel” (comp. e.g. Exod. 12:3 with ver. 21; Lev. 9:1 with ver. 5). But through whatever medium conveyed, it was to the people that these words were addressed; this is emphatically a book for the people. (The Pulpit Commentary: Deuteronomy 1:1)