Bad audio recording quality with iMessage/whatsapp on iPhone 6 - iOS 8.3 + 8.4

I'm experiencing terrible audio quality on my recordings in iMessage & Whatsapp.

This started happening on IOS8.3 and is still present in IOS 8.4.

It sounds terrible, like highly compressed, muffled and very faint. (low volume).

When I record a video with the Camera app, there's no problem at all with the sound.

any ideas?