What situation applies according to this traffic sign?

This traffic sign indicates a speed limit of 30 km/h, specifically during the hours of 10 PM to 6 AM for noise protection purposes (Lärmschutz). This is often implemented in residential areas to minimize noise disturbance during nighttime.

The sign is a reminder that vehicles must adhere to this reduced speed limit to ensure a quiet environment for residents during the night. It is essential to follow this regulation, as violating it can lead to fines or other penalties.

Understanding the timing and purpose of such regulations is important for responsible driving, ensuring community comfort and safety during designated quiet hours.