Hi all, this may sound like a silly question, but, is there anyway to test a dogs hearing?

Lately Gus has been unresponsive to certain noises when he is asleep, like someone arriving home or coming into/making noise in the room where he is sleeping. I thought as he was getting older he was sleeping deeper than usual.

Recently he doesn't always hear people behind him, an example of this was...last week my son came to visit. When the porch door slid open the dogs were in the kitchen and DJ and Pippin looked behind them at the front door, while Gus stayed looking at me. My son opened the front door and the other dogs went to greet him, still Gus didn't turn round. We both realised he didn't seem to hear, so my son rattled his keys and called him, still no response. I was talking to my son and Gus still didn't notice. I pointed to my son with gus looking at me and Pippin came back as if to tell Gus my son was there. Only then did Gus turn around and was extremely excited to see my son had come to visit. I notice lately if I want Gus to leave a room and he's looking in the opposite direction to me I need to go and direct him. I thought he was just ignoring me!

What confuses me is that sometimes he appears to hear and then at other times he appears totally deaf. He was on the bed this morning when I woke uo and he was awake so I called him but he didn't even look in my direction but when he seen me in the morror sitting up he turned and came to me wagging his tail. Then just a few minutes ago I whistled to call Pippin and DJ from the garden and Gus who was standing beside me, lifted his ears back to hear..but maybe that's because it's high pitched?

Any ideas or opinions?

Thanks for reading