What are the tones used by audio engineers and videotape operators to calibrate playback and video signals called?

• A. Calibration Tones
• B. Tones or Reference Tones
• C. Test Tones
• D. Reference Tone

Answer: (B)

Calibration relies on reference tones—stable signals with known levels and frequencies that let you set and verify playback and video timing accurately. By using tones at standard levels (often multiple tones at different frequencies), engineers can align meters, confirm channel levels, and ensure consistent performance across equipment. The phrase that says tones or reference tones best matches real-world usage because these signals are commonly just called tones, or specifically reference tones in technical settings, and you may use more than one tone for calibration. This inclusivity makes it the most accurate description for what these signals are called.