Regarding Ferrite Bead
Here's a fairly generic picture of a ferrite bead: -




At low frequencies (&lt;10 MHz) its impedance is dominated by its reactance with resistive losses being low. It's basically operating like a piece of ferromagnetic material i.e. it is an inductor
As frequency rises, inductive reactance drops away due to eddy current losses in the core material. This also gives rise to extra resistive losses.
At high frequencies "losses" dominate the impedancee curve thus making a series-connected ferrite bead useful as an attenuator of unwelcome high frequency RF interference
At very high frequencies parasitic capacitance makes the bead less useful


Ferrite beads tend to be useful from 10 MHz onwards. At 8 kHz they are generally useless.