There is minimal leakage from this Epson design. That has been true of all the Epson UB's using this basic design, essentially, starting with the 6500UB.
Epson claims 22 db in eco mode and 28 at full power. 28 is pretty good for full power, quieter than any of the DLP projectors, even at several times the price. The iris noise is minimal by my reckoning. The 8350 has been sitting 3 feet behind me and 18 inches below me, for most of a week. all my viewing has been with the lamp on full power. Never noticed the noise, but then, I know some folks are far more sensitive to background noise. In low power mode (eco mode), the 22 db isn't the quietest projector out there, but is close to silent, for all practical purposes.