Unsupported Macbook 4,1 (2008) on 10.10.5 (Supplementary) - No Audio After Update - What Next?
Hello I've the solution.
Download this audio kext.
Drag the two files AppleHDA.kext and IOAudioFamily.kext into the kext utility.app
After all is ok you can reboot and it works :-)

Link : https://mega.nz/#!9hcgFKRK