Hi, and welcome to the Apple (user-to-user) Community.
Re: "Hearing Aid Feature on AirPod Pro 2" : " ... the biggest problem is I also hear my own voice speaking loudly and slowly as a sort of delayed speech. This makes the hearing aid part totally useless. This does not happen when I am on a phone call. "
Am no expert in this area, yet your post to the community deserves some response.
Fortunately, Apple Support documents "how to" info. so we can browse through the various possibilities.
If you haven't already viewed this article, it does provide many tips:
Use the Hearing Aid feature on your AirPods Pro 2 - Apple Support
Eg: says:
"Adjust amplification level, balance, and more in AirPods Pro settings"
"You can adjust settings like amplification level (how much your AirPods amplify the sound around you), left-right balance, tone, and Conversation Boost on iPhone, iPad or Mac (requires macOS Sequoia 15.1 or later). For quick access to settings, you can use Control Center to adjust settings." ( Follow the steps in the article.)
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You might want to experiment with microphone settings:
See: Active Noise Cancellation and Transparency modes for AirPods - Apple Support
if using AirPods Pro 2 with a Mac, you can try: Use Mic Modes on your Mac - Apple Support
Also: you may want to try / customize Adaptive Audio:
Use Adaptive Audio with your AirPods - Apple Support
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Change the settings of your AirPods and AirPods Pro - Apple Support
Eg: says:
"By default, when you press and hold the force sensor on the stem of your left or right AirPod, your AirPods switch between Active Noise Cancellation and Transparency mode. You can change which noise control modes the press-and-hold action uses".
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Else: Wondering if replies in this earlier thread may be helpful ...
seems the situation of hearing one's own voice "echo" existed even before the hearing-aid feature.
Discussion thread:I hear my own voice when using my air pod… - Apple Community
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Other Resources:
AirPods Support Website:
"Find all the topics, resources, and contact options you need for your AirPods...."
AirPods Support - Official Apple Support
AirPods User Guide :AirPods User Guide - Apple Support
All the best :-)