I don't believe those issues are related to the update... As far as my experience goes, the voice search issue was that no sound was picked up by the microphone at all -- easily identified by the fact that there was no "sound wave image" or mic flashing.Others are saying the voice search issue (does not work when driving) was not fixed. Can you confirm that it works while driving in a car (or with other background noise).
As for interference and the inability to identify words when there is background noise... I think that's just how it goes, I don't believe that's an update issue.
. I really wish I hasn't done that.