Some transmission coefficients for common materials @ 2 GHz:
Brick: -4 dB
Plexiglass: -0.35 dB
Glass: -0.5 dB
Drywall: -0.5 dB
Particle Board: -1.6 dB
Plywood: -2 dB
Cinder Block: -6.7 dB
For refernece:
Human abdomen: - 50 dB (150 mm thick)
Simply put, biological systems are very lossy. Your wood door on an entertainment system won't be an issue.
For those who don't understand decibels: 3 dB is a loss in power density of 2x, 10 dB is 10x, 20 dB is 100x.... 50 dB is a loss in power density of 100,000x
Of course since the antennas in these devices are not very directive there are lots of reflected paths to the receiver and the total loss is not as high as the line of sight transfer function.