| Answer | Crossword Clue |
|---|---|
| optophone | a device transforming light into sound |
| optophones | OPTOPHONE, a device transforming light into sound |
| filtering | Pass (a liquid, gas, light, or sound) through a device to remove unwanted material |
| filtered | Pass (a liquid, gas, light, or sound) through a device to remove unwanted material |
| echelle | a device for splitting light into its component colours |
| echelles | ECHELLE, a device for splitting light into its component colours |
