I, too, am having this same problem! When making or receiving calls on the speakerphone of my iPhone X, the audio quality is absolutely horrible! There is static, crackling and distortion — it sounds like the speaker is peaking. Plus, the overall volume is much softer than it was on the iPhone 7. I took my iPhone X back to the Apple store in Walnut Creek, California and they gave me a replacement, but the same problem occurred on the replacement. For what it’s worth, when the Apple Store did a full audio diagnostic test on my original iPhone X and the replacement iPhone X, the results for both phones came back as if there was nothing wrong with the phones. So, the audio diagnostic tests do not properly pick up on the horrible distorted speakerphone sound. Hopefully, Apple will realize that this is an issue and get it fixed, whether it is fixable through software or the phones have to be replaced. After all, beneath all of the glitz, these devices are telephones, and we should be able to hear the people we are calling with with some degree of clarity — especially from an $1100 phone.