Assignment Questions
A studio has the dimensions: length 8m, width 5m and height 2.4m.
Standing Waves –
Work out the frequencies and mode numbers of the 10 lowest frequency standing waves, sorted by frequency (ignoring 0 Hz)
[3 marks]
Reverberation Time Optimisation
Choose appropriate materials (using the table below) for the different surfaces to reduce the reverberation time to around 300 msec. at 500 Hz.
This result should be submitted as a spreadsheet, with any formulae in situ.
Use the Sabine formula to do the calculations on a spreadsheet.
Marks will be awarded on
closeness of result at 500 Hz [9 marks]
how sensible the materials are [2 marks]
unique result . [1 mark]
| Effective absorption coefficients |
Frequency, Hz |
||
| Material |
125 |
500 |
2000 |
| Acoustic panelling |
0.16 |
0.50 |
0.80 |
| Acoustic plaster |
0.30 |
0.50 |
0.55 |
| Brick wall, unpainted |
0.02 |
0.03 |
0.05 |
| Draperies, light |
0.04 |
0.11 |
0.30 |
| Draperies, heavy |
0.10 |
0.50 |
0.82 |
| Felt |
0.13 |
0.56 |
0.65 |
| Floor, concrete |
0.01 |
0.02 |
0.02 |
| Floor, wood |
0.06 |
0.06 |
0.06 |
| Floor, carpeted |
0.11 |
0.37 |
0.27 |
| Glass |
0.04 |
0.05 |
0.05 |
| Marble or glazed tile |
0.01 |
0.01 |
0.02 |
| Plaster |
0.04 |
0.05 |
0.05 |
| Rock wool |
0.35 |
0.63 |
0.83 |
| Wood panelling, pine |
0.10 |
0.10 |
0.08 |