TOPIC:

I suggest to set noise concern limitations per each company separatly.
According to current settings for noise concenrs, one player (by building the airport) blocks another player's ability to build an airport. This is a kind of contradiction to server rule about blocking.
I think setting noise concern limitations separatly for each company will make game more fair.

False, as it's not land claiming and there isn't intentional blocking in normal operation of airports. They can, just like with claimed area, be used for blocking. At that point rule 5 is broken. Due to what I just said I don't really see a reason personally in adjusting how noise concerns work.

Due to what I just said I don't really see a reason

You contradict to yourself, because land reserving is forbidden by the rules, but building of airports is not forbidden.

Furthermore, the noise limitation mechanics implemented in the game is unrealistic. There is no such limitation in real world. As a person, whose work is related both to aviation and to noise, I will dare to briefly explain you how noise limitation works in reality:
Sound pressure level may be monitored in the populated areas. Based on sound pressure level time history an equivalent sound pressure level or sound exposure level is estimated. Such estimation requires an integration of sound pressure over time. This implies, that the result will depend on the number of noise events. Then equivalent sound pressure level or sound exposure level (depends on the country) is compared with normative documents, where the values vary depending on noise frequency, type of populated area (dwelling, commercial, industrial), number of people irritated by noise.

If I implemented noise limitation in game, I would introduce some assumptions:
1. Noise is limited based total noise characteristics, which is integrated over whole audible frequency range. Though, this never takes place in reality because people perceive sound on different frequencies unequally as well as vehicles produce different sound pressure levels at different frequencies. But this assumption simplifies noise limitation, because only one value how to be controlled by players instead of array of values corresponding to each frequency.
2. The computation of equivalent sound pressure over the game map have to be performed based on sound propagation from station tiles. In reality, vehicles are the noise sources, but not the stations. However, if vehicles are considered as noise sources, soundscape will change dynamically with vehicle motion. This will cause severe computational load on server or clients; make game overcomplicated and hard for players.
3. Noise diffraction, refraction, reflection from building in cities and from ground on landscape level differences, noise attenuation due to meteorological conditions are neglected.
These assumptions allow to write an oversimplified formula for computation of equivalent sound pressure level L on each game map tile:
L=10*log10(sum(10^0.1*Ls));
where Ls is equivalent sound pressure level caused by station tile:
Ls=10*log10(sum(10^(0.1*Lp))/(N*D))-20*log10(R)-10*log10(4*pi),
where Lp is sound power level of vehicle departure/arrival from/to station (values must be listed in vehicle build gui similar to vehicle speed), N is total number of departure/arrival events for considered station during time period D (which may be a time period at which noise map is updated); R=sqrt((xs-x)^2+(ys-y)^2) is distance from tile for which calculation is performed (having coordinates x and y) to station tile (with coordinates xs and ys); pi= 3.1416…

Player pay fees for each city building tile, where equivalent sound pressure level exceeds set normative value for that building type. Also local authorities must restrict building of station, for which set number of noise events for reference vehicle type cause excess of equivalent sound pressure level.

This kind of approach will make game interesting, realistic and fair.

P.S. I believe, that by reading this, you will start to understand how much term “noise” is irrelevant to limitations implemented in the game.

You're wasting your breath here. Server admins can't do this kind of stuff, only changing noise limits is possible. For altering noise mechanics itself you should ask game developers. Though keep in mind that they don't really care about blocking, competition and goal servers in general.

P.S. And forget about realism argument, everyone is sick of it already.