Question about Google Pixel 8 Pro

Hello Digitec and Community I've had the Pixel 8 pro since April and I love it. Everything is really great except for one thing that I haven't managed to optimise yet. Maybe someone has experience or tips on this. It's about the call quality or the call volume. If you use the smartphone normally without any headphones, the caller is simply too quiet. The volume is at maximum, but as soon as there is some ambient noise, it is difficult to understand the caller. I have already optimised the call quality in the settings under "Sound and vibration" and also switched on the "Crystal clear calls" function, but it is still not optimal. Are there any other ways to optimise this or simply increase the volume? Any other tips? Thanks for your feedback.