A sound wave travels from the air in a workshop into an aluminium layer in a test panel, then from the aluminium into an acrylic layer. The sound speeds in the three materials are shown in the table.
| Material | Speed of sound in m/s\text{m/s}m/s |
|---|---|
| air | 340 |
| aluminium | 6400 |
| acrylic | 2750 |
Explain what happens to the speed, frequency and wavelength of the sound at each of the two boundaries. Use data from the table in your answer.