how many decibels do these block (beats studio buds)

Noise-cancellation works by listening for noises and creating an inverse waveform that is equal. When the synthesized noise and the ambient noise meet at your ear, the noise-level of what you hear is reduced. It works great for jet engine noise on a long flight. But non-repetitive noises can not canceled by this technique.

No promises of reduction to a certain level are possible.

If you need hearing-level SAFETY Noise reductions, you will need to use traditional safety equipment such as "earmuff" style noise reducers.