BeechTalk - BT

Username Protected · **Posted:** 04 Jan 2018, 17:29

Username Protected wrote:

The microphone circuits can have auto leveling gain which fool the apps, particularly in loud situations.

Which would suggest that even the same phone used later would not register consistent results. Darn.

Username Protected · **Posted:** 04 Jan 2018, 17:33

Username Protected wrote:

Unless you use calibrated sound meters, the results won't mean much.

That's a fact. When I was fighting cabin noise problems, I downloaded an app for my iPad. It was basically worthless because it wasn't repeatable.

Username Protected · **Posted:** 04 Jan 2018, 23:17

When I sound insulated my Cardinal RG, I used a Radio Shack sound meter for before and after comparisons. Before any work I measured the following: Full power climb (28.5` and 2700 RPM) A weighted 101 dB, C weighted 107 dB. Cruise power (27` and 2300 RPM) A weighted 98 dB, C weighted 101 dB. After all the work: Full power climb (28.5` and 2700 RPM) A weighted 98 dB, C weighted 103 dB. Cruise power (27` and 2300 RPM) A weighted 87 dB, C weighted 95 dB. Measurements were taken at ear level between the two front seats.

I changed all the windows to a thicker version. I used two types of insulation densities in the cabin walls and ceilings and a foil backed matt under the carpet and against the firewall.

BTW, I used the same meter to measure the noise level at my window seat on a 737, right next to the engine, and got an A weighted reading of 93 dB.

Vince

Username Protected · **Posted:** 05 Jan 2018, 11:40

Username Protected wrote:

This will be interesting to do on my A36.. In a few weeks I will have all new glass installed. 3/8 front 3 and 1/4 on the back 6. will see if it makes a difference.

Air infiltration creates the most noise, especially from the emergency windows. You need to start there.

Sound Level Thread for All Aircraft