Hy, i have news, i think that is not a Software Issue.
I downgrade in steps from latest 1.97 > 1.95 > 1.86 > 1.85 > 1.66
in all Versions its the same, the Phone Speaker have permanent noise (comparable with Hi-fi noise without signal)
i mean this comes from the duplex audio chipset, i change the model to a newer Series