The 3 vs. 7 meter debate aside, I've found the Honda, Yamaha, and Champion generator db ratings generally useful and reflective of realworld performance.
The Champion 3100 is rated at 58 db at 25% load (700 watts). The Honda EU2000i is rated at 53 db at 25% load (400 watt) and 59 db at 100% load (1600 watts). I've had plenty of opportunity to listen to these two generators operating side-by-side under differing loads. Put a 25% load (700 watts) on the Champion 3100 and a 100% load (1600 watts) on the EU2000i and you'll find there is no remarkable difference in sound level (both with eco mode on). Both are still somewhat quiet. However, if you increase the Champion 3100's load to 100% (2800 watts) the sound level goes up significantly. Under 100% load (2800 watts) the Champion 3100's sound level approaches the level of a "quieter" open-frame generator---IMO, approx. 65-66 db.
IMO, advertised db levels are generally useful and reflective of realworld performance as long as the load level is also factored into the db comparison.
