The passive voice is often preferred in formal speech for several reasons:

1. Creating a Neutral and Impersonal Tone: The passive voice helps to focus on the action or the object of an action rather than the doer of the action. This can create a more neutral and impersonal tone, which is often desired in formal settings to maintain professionalism and objectivity.

2. Avoiding Direct Attribution: In contexts such as politics, law, or official statements, using the passive voice allows speakers to avoid directly attributing actions to specific individuals or entities. This can be useful when the speaker wants to shift the focus away from who is performing the action and instead highlight the action itself.

3. Enhancing Professionalism and Objectivity: Using passive voice can enhance the perceived professionalism and objectivity of a statement or presentation in formal settings by emphasizing the action or the topic rather than the subject performing the action. This can help to convey a sense of authority and seriousness.

Overall, passive voice in formal speech can be a strategic linguistic choice to convey complex ideas, maintain objectivity, and present information in a professional manner without explicitly assigning responsibility or blame.