interior noise level 71dB at 70mph
08-30-2018, 02:51 PM
#31
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Wow! Forties are almost library-quiet. Maybe the high school library...
I fly a lot (not as much as Tony and the other professional plane drivers) and wear earplugs and Bose ANC headphones the whole time. I generally get to ride in the front cabin, in front of the turbine air inlets. The iPhone app shows consistent low 80's at cruise, low 90's on takeoff. Varies slightly depending on aircraft type and window vs aisle seat, but consistently too loud for chronic exposure. I also get to wander around noisy equipment in power plants. A typical work environment these days is tucked into a server room with lots of computer and HVAC fan noise. Same deal -- Ear plugs and ANC headphones.
I just got a new phone and haven't yet installed the sound pressure app. Decent dedicated sound pressure meters are not at all expensive, so maybe our measurements standards need to move away from uncalibrated phone apps to actual repeatable test methods.
---
Replacing the gearbox mounts helped some based on seat-of-the-pants readings. With the mounts partially collapsed, not bad. Add some filler to restore the height, and suddenly there's a mechanical cacophony transmitted up through the tub. New mounts, and all's quiet on the southern front again, relatively. At speed there's transmitted tire noise to contend with. Adding insulation or even damping pads inside in the wheel arches may help a little, but there's a lot more noise-grabbing metal around the tires than just the inner wheel arch area. I may stuff a poly bag up into the B-pillar area and fill it with minimum-expanding foam to stop the noise going up into the roof area. Otherwise there isn't a lot that can be done for rear tire noise, unfortunately.
I fly a lot (not as much as Tony and the other professional plane drivers) and wear earplugs and Bose ANC headphones the whole time. I generally get to ride in the front cabin, in front of the turbine air inlets. The iPhone app shows consistent low 80's at cruise, low 90's on takeoff. Varies slightly depending on aircraft type and window vs aisle seat, but consistently too loud for chronic exposure. I also get to wander around noisy equipment in power plants. A typical work environment these days is tucked into a server room with lots of computer and HVAC fan noise. Same deal -- Ear plugs and ANC headphones.
I just got a new phone and haven't yet installed the sound pressure app. Decent dedicated sound pressure meters are not at all expensive, so maybe our measurements standards need to move away from uncalibrated phone apps to actual repeatable test methods.
---
Replacing the gearbox mounts helped some based on seat-of-the-pants readings. With the mounts partially collapsed, not bad. Add some filler to restore the height, and suddenly there's a mechanical cacophony transmitted up through the tub. New mounts, and all's quiet on the southern front again, relatively. At speed there's transmitted tire noise to contend with. Adding insulation or even damping pads inside in the wheel arches may help a little, but there's a lot more noise-grabbing metal around the tires than just the inner wheel arch area. I may stuff a poly bag up into the B-pillar area and fill it with minimum-expanding foam to stop the noise going up into the roof area. Otherwise there isn't a lot that can be done for rear tire noise, unfortunately.
