Over modulation occurs due to what main issue?

The correct option highlights that over modulation typically occurs when an individual speaks too closely to the microphone. This situation can cause distortion in the audio signal; when the sound waves are overly forceful or the volume levels exceed what the microphone can handle, it leads to clipping or distortion of the audio.

When speaking very close to the microphone, the proximity effect often amplifies certain frequencies, particularly bass, which can create an imbalance in audio and overwhelm the system. It's essential for operators to maintain an appropriate distance to ensure a clear, concise audio transmission without distortion.

In contrast, using a faulty microphone could lead to other issues, such as poor sound quality or intermittent connection but isn’t a primary cause of over modulation. Speaking softly typically results in lower volume and may not reach modulation thresholds. Adjusting volume levels too high could induce distortion as well but is considered more of a separate factor that could exacerbate existing modulation problems rather than being the root cause.