Proper way of using adverb

Question

I know the first one is correct, but what about the second one? Would that be still?

1. I could hardly hear her voice.
2. I could hear her voice hardly.

Answer 1

Your second sentence is not correct. hardly is an adverb with particular use when it comes to word order. Cambridge says

We usually put hardly in mid position, between the subject and the main verb, or after the modal verb or first auxiliary verb, or after main verb be:

My piano lesson is on Monday, and I’ve hardly played it this week.

I can hardly wait.

There were hardly any tourists.

When hardly is modifying either the main verb or the following noun, we can put it directly before the verb or before the noun phrase:

She hardly had any sleep. or She had hardly any sleep.

In more formal styles, to refer to something happening immediately after something else, we use hardly … when. We move hardly to front position and invert the subject and verb:

Hardly had I arrived there when I was called back to the head office 100 miles away. (I arrived there and then I was immediately called back.)

There are adverbs which could be used in the position you gave hardly in your second sentence though:

I could hear her voice clearly/constantly/vaguely.

Answer 2

"hardly hear" would be the typical expression. The second sentence looks wrong. The placement of adverbs varies, and they can often appear at the beginning or end of a sentence. However, sometimes the adverb is expected to be right next to the verb, in a similar way to an adjective which is placed right before a noun. Such is the case here.

Answer 3

• I could hardly hear her voice. or
• I hardly could hear her voice.

The first is the most used.

Putting an adverb like hardly at the end is a mistake.