The purpose of the small round hole at the bottom of the phone:

The small round hole at the bottom of your phone is actually a secondary microphone, playing a crucial role in the dual microphone system that helps reduce noise. This is a noise-canceling microphone, integrated into most modern smartphones. Thanks to this microphone, your calls will be clearer and of higher quality. Without it, your voice wouldn’t be transmitted clearly to the listener.

Even in noisy environments, you can still hear and transmit your voice clearly thanks to this small hole. Placing the microphone at the bottom of the phone near your mouth helps capture and transmit your voice better, enhancing call quality.