Table 1 Summary of anechoic box designs used in related research projects.

²⁹

Single wall:

1. 19 mm plywood

2. 3.2 mm loaded vinyl

3. 76.2 mm foam

4. 3.2 mm loaded vinyl

5. 6.4 mm plywood

6. 152.4 mm foam wedges

81 kg

50 dB to 70 dB between 1 kHz and 10 kHz

¹²

Single wall, cylindrical:

1. 1 mm steel wall

2. 50.8 mm foam wedges

3. different types of foam

vinyl, aluminium and lead used to build an entering funnel and a lid

70 kg including the pedestal

4 outside microphones to monitor outside noises

60 dB to 90 dB between 1 kHz and 10 kHz

¹³

Double-wall:

1. 18 mm plywood

2. 50 mm of acoustic foam

3. 50 mm air gap

4. 18 mm plywood

5. three different density foams compressed to 2/3 of their thickness

6. 18 mm plywood

Unknown

Inside box suspended from springs inside the outside box

Not tested

¹⁰

Double-wall:

1. 30 mm MDF-Board

2. 50 mm air gap filled with glass wool

3. 30 mm MDF-Board

4. 150 mm acoustic wedges, with 30 mm base

220 kg just the inside box

Double-deflection neoprene mounts to mount the inside box inside the outer box

More than 50 dB as low as 200 Hz (Simulation)

¹¹

Double-wall:

1. 30 mm MDF-board

2. air gap

3. 30 mm MDF-Board

4. 300 mm acoustic wedges

Unknown

Not tested

¹⁴

Double-wall:

1. Concrete

2. Foam

3. Light concrete

4. 700 mm acoustic wedges, with 300 mm base

387,000 kg

Entire box placed on springs isolators

More than 50 dB as low as 100 Hz (Simulation)