When i say hey siri he/she doesn’t respond but my listen for hey siri is on

Here are a couple things to consider. First is to retrain him/her to hear your voice command:

Set up "Hey Siri" to help Siri recognize your voice

1. Go to Settings.
2. Tap Siri & Search.
3. Turn off Listen for "Hey Siri," then turn it back on.
4. When the Set Up "Hey Siri" screen appears, tap Continue.
5. Say each command that you see on your screen.
6. Tap Done.

If Siri still isn't reponding

• By default, Siri won't respond when your device is face down or covered unless you go to Settings > Accessibility > Siri and turn on Always Listen for "Hey Siri."
• If Lower Power Mode is turned on for your iPhone, you can't use "Hey Siri."

What year and model iPad do you own?