Voicever and pop sound when speaking text and swishing sound when move finger over home button on IPhone 6

Hi,

I am noticing a pop sound when Voiceover reads items sometimes for example Iwas Using the UK train times app just now and it is saying 8.14 to London and then a pop sound and then it says on time button. Is this a sound effect apple has added in IOS8 to signify buttons or is it a bug?

Also the Iphone 6 has a fingerprint censor built into the home button. When the phone is unlocked and if I hold my finger over it and move it around slightly for a few seconds, I hear a swooshing type sound effect. Have you encountered that? What is the purpose of that sound effect?