| Clue | Source | Date |
|---|---|---|
| Cause of redshift, eg | The Times Concise | 23 Mar 2026 |
| Perceived change in sound, due to movement | The Telegraph Quick | 02 Mar 2025 |
| The speeding sound difference was a perfect flop, Ed (7,6) | ||
| Changes of wave frequency causing the rise and fall of pitch as a train passes you | The Times Specialist Sunday | 24 Mar 2019 |