When conducting outdoor auditory illusion research, selecting the right furniture is crucial to minimize interference and enhance sound accuracy. The ideal outdoor furniture should have specific acoustic properties to reflect, absorb, or diffuse sound waves effectively.

1. Metal Furniture: Aluminum or steel tables and chairs are excellent for sound reflection due to their hard surfaces. However, they may produce unwanted echoes, so positioning is key.

2. Wooden Furniture: Teak or cedar offers natural sound absorption, reducing background noise. Their porous structure helps dampen high-frequency sounds, making them suitable for controlled experiments.

3. Wicker/Rattan: These materials scatter sound waves, reducing direct reflections. Their lightweight nature also minimizes vibration interference.

4. Concrete Benches: Dense and solid, concrete provides consistent sound reflection but may require additional padding to avoid harsh reverberations.

5. Fabric-Upholstered Pieces: Outdoor sofas with thick cushions absorb sound, ideal for reducing ambient noise in open spaces.

For optimal results, combine different materials to balance reflection and absorption. Avoid plastic furniture, as it often distorts sound. Always test setups with audio equipment to ensure minimal acoustic disruption.