John 12:29

The multitude therefore, that stood by, and heard it, said that it had thundered: others said, An angel hath spoken to him.

That some of the multitude heard the words is obvious. The apostle John heard and understood the words himself, without any need of anyone's interpreting them to him (for no such thing is mentioned). Thus it may be assumed that they were intelligible words, wanting only attention on the part of hearers to be understood. As Frank L. Cox expressed it:

Here we have an illustration of the fact that people often hear things differently according to what they are themselves. Some hear thunder, others an angel's voice, but Jesus understood.[19]

It is one of the mysteries of life that some see and hear the things of God, and others do not see nor hear. Daniel was by the river Hiddekel when he saw the holy vision, but his companions were not aware of it; and Paul's companions on the Damascus road heard the noise but not the words of the Lord out of heaven.