They also included heavy soundproofing, including of foam insulation throughout the body. Optional cabin equipment includes soundproofing, air conditioning, and bleed air heating. The main cabin area is furnished with soundproofing measures, ventilation, and heating as standard. Great White accidentally ignited flammable soundproofing foam. It is also used to insulate piping and for soundproofing. Vehicle soundproofing can reduce wind, engine, road, and tire noise. The club's ceiling was supported by pillars, which were coated with a flammable soundproofing foam. The club was coated on the inside with foam that was used for soundproofing. The interior was also redesigned with new fabrics and improved soundproofing. It also featured extra soundproofing and a roof liner made using West of England cloth. The thickness, typically , and density of rammed-earth walls make them suitable for soundproofing. Different widths and densities in soundproofing material reduces sound within a variable frequency range. For increased passenger comfort, the cabin is both pressurised and equipped with soundproofing. Acoustic absorption is of particular interest in soundproofing. Vehicle soundproofing can reduce sound inside a vehicle from five to 20 decibels.