When we say that there’s a lack of speech privacy in this environment, this indicates a low privacy index score. The privacy index is a way of measuring how intelligible speech is across a given space. In a given environment, there are three ways you can improve your speech privacy score, often referred to as “the ABC’s”:
You can Absorb the sound with panels or better ceiling tiles,
You can Block the sound by building walls or furniture partitions,
and You can Cover the sound by installing a high-quality sound masking system.
However, these three tools are not mutually exclusive. Think of the speech privacy index as a dartboard. In darts, you’re looking for a good TOTAL score, and you add your throws together. This is how the privacy index works: you take some mix of the ABC’s – the three darts, so to speak – and add up the score to get you to your desired privacy index level. In most cases, that means achieving a PI score of at least 80%. 
That said, all of your darts are not equal.
In terms of their relative effectiveness, Covering usually gives you the most bang for the buck, providing the biggest increase in privacy per dollar spent. Therefore, covering (i.e. sound masking) is where we’ve started. Remember, though, that this is one of three “darts,” and many workspaces will require more than one “throw” to get the desired score.