Audio hissing existed since february update, it's not fixed until now. Praying hard that the april update will fix it. Super catastrophic
I contacted Nokia about the volume and audio-timeout issues. I just received the following reply, but I'm not sure which issue they're referring to. Hopefully both.
We would like to inform you that there will be an OTA update by the end of this month that will provide a fix for this issues you are experiencing. If you need any additional help or have any questions, please, don't hesitate to contact us! Kind regards, Nokia Mobile Care team