Free noise level measurement
Quick and free noise level measurement can be carried out by every owner of a personal computer or smartphone. To determine the noise level in a residential area, you can download special applications. An example of such applications would be "Sound Meter : Sound Meter" (for smartphone) or Decibel Meter (for Windows PC), which require only working speakers of the measuring device to work. Applications are easy to use and available to anyone.
However, the results of such a measurement will not have strong legal force in litigation, since the examination must take into account many factors that are not recorded by the tenant when independently measuring the noise level using a computer application.
1. Carrying out the measurement
Microphone follows
be placed at a height of 1.5 m above the level
floor or work area (if work
performed standing) or at ear height
person exposed to
noise (if the work is done while sitting).
The microphone must be oriented
direction of maximum noise level
and removed at least 0.5 m from the operator,
conductive measurement.
For Noise Evaluation
at permanent workplaces measurements
should be carried out at points corresponding to
established permanent locations.
For Noise Evaluation
at non-permanent workplaces measurements
should be carried out in the working area at the point
the most frequent stay of the worker.
When conducting
measurements of octave levels of sound
pressure switch frequency
device characteristics set
to the filter position. Octave
sound pressure levels are measured in
bands with geometric mean
frequencies 63-8000 Hz.
When conducting
measurements of sound levels and equivalent
sound levels, dBA, switch
instrument frequency response
set to position "A".
When conducting
measurements of sound levels and octaves
constant sound pressure levels
noise switch time response
the device is set to the position
"slowly". Level values
taken according to the average
fluctuation of the instrument needle.
Level values
sound and octave levels of sound
pressure is read from the instrument scale with
accurate to 1 dBA, dB.
Level measurements
sound and octave levels of sound
constant noise pressure should be
carried out at each point at least three
once.
When conducting
measurements of equivalent sound levels
time fluctuating noise for
definitions of equivalent (in terms of energy)
sound level switch timer
device characteristics set
to the "slow" position. Values
sound levels are taken according to indications
arrows of the device at the moment of counting.
When conducting
measurements of maximum sound levels
time fluctuating noise switch
time characteristic of the device
set to the "slow" position.
Sound levels are taken at the moment
maximum instrument reading.
When conducting
measurements of maximum sound levels
impulse noise switch timer
device characteristics set
to the "impulse" position. Values
levels are taken at the maximum
instrument indication.
Reference intervals
sound levels fluctuating in time
noise when measuring the equivalent
levels lasting 30 minutes
are 5-6 s with a total number of readings
360.
When conducting
measurements of equivalent sound levels
intermittent noise switch
time characteristic of the device
set to "slow"
measure sound levels and duration
every step.
Expert research methodology
So
forensic examination of an accident should be divided
into the following types (see Fig. 4):
Rice.
4. Main types of road accident expertise
As a result
carrying out some of the described types
examination of an accident (Fig. 4), one of the
the most important issues - corresponded
whether the actions of the driver of this road
environment.
Conclusion
expert is the most important tool
evidence of guilt/innocence
in motor vehicle crime cases.
It contains the most important evidence
information obtained through
conducted on the basis of scientific data
research, as well as actual
circumstances set out in
criminal/civil case. Exploring
provided initial data, expert
in accordance with the
him with questions sets the whole
accident mechanism. It should be noted that
regardless of how it is done
expertise and from the applied
technical means procedural
the role of the expert in all cases remains
unchanged. As with automation
expertise (using a specialized
software) and without
her expert gives an opinion from his
name, signs it and bears for it
legal responsibility.
Task: Determine
type of examination of an accident, as well as draw up
algorithm for analyzing the presented
traffic accident.
1. Determination of vehicle speed
most objective
indicator that can
determine the speed of the vehicle (for a linear
braking to a complete stop, see fig.
6, 7) at the moment preceding the collision
or collision (i.e. at the stage of rapprochement -
contact), are traces of braking
(traces of skidding) left by the tires of the vehicle on
road surface. If in place
traces of the incident
braking of the vehicle, then its speed with
a sufficient degree of accuracy
be determined by formula (1), km/h.
Rice.
6. Linear braking of the vehicle to its full
stops
Rice. 7. Option
linear
deceleration of the vehicle until it comes to a complete stop
(1)
where 1.8;26 are constants
coefficients (convertible); T3
– vehicle deceleration rise time, s
(estimated, time since contact
brake pads and disc or drum
until the wheel locks) J
– steady-state deceleration of the vehicle, m/s2;
SYu
- length of brake skid tracks, m, from
road accident schemes in the materials of the traffic police check;
B - vehicle base, m.
If during the investigation
Accident brake marks do not come from the front
wheels, or we are talking about low
braking efficiency of the rear wheels,
then the base of the vehicle from formula 1 is not subtracted.
If the vehicle was moving
on asphalt concrete pavement, then,
hitting an obstacle
height (e.g. on a pipe), continued
driving on a different type of surface
(for example, soil, see Fig. 7a), then
vehicle speed is calculated
according to formula (2).
(2)
where Ja
- installed on asphalt concrete
coating deceleration TS, m/s2;
JG
– ground-based deceleration
TS, m/s2;
Syua
- the length of the traces of the brake skid on
asphalt, m; Ssouth
- the length of the brake skid marks on the ground,
m; g
- acceleration of gravity, g
= 9.8 m/s2;
h
– obstacle height, m.
Rice.
7a. An example of different types of road
coverings separated by any
obstacle
If road
coating (asphalt) smoothly into
roadside (ground, see Fig. 7b), speed
calculated by formula (3):
(3)
where S1
- the length of the traces of the brake skid on
asphalt, m; S2
- the length of the brake skid marks on the ground,
m.
Rice. 7b. Example
different types of pavement
If after
braking, the vehicle moves freely
coasting (see Fig. 8a), then its speed
will be calculated by formula (4).
Rice.
8a. Freewheeling of the vehicle after
braking
(4)
where f
- coefficient
rolling resistance, f
= 0,02; Sn
- run-up path, m.
If the trail of yuza
port side and starboard side are different
(see Fig. 8b) - this does not mean that it is possible
assert a malfunction of the brake
systems. This outcome can be influenced
as the distribution of mass on the machine, so
and the condition of the road surface (presence
sand particles on the roadway, bald patches
with ice, potholes, etc.). In this case
the maximum value of traces is taken
yuza.
Rice.
8b. If after the vehicle there are traces of skidding
different sizes
Reasons for measuring noise in an apartment
Constant background noise above the level allowed by sanitary codes in a residential area interferes with the sleep and rest of residents, and also reduces working capacity and concentration. Due to prolonged exposure to noise, a person can acquire neurological problems, suffer from headaches and migraines.
Helpful information
The permissible noise level is regulated by the so-called Silence Law (FZ No. 52). According to the law, the noise level from 7.00 to 23.00 can be no higher than 55 dB. Read more on our website here
During the construction of an apartment building, the developer is obliged to adhere to sanitary standards for soundproofing residential premises so that residents can relax without harm to health. If residents of an apartment building are disturbed by constant background noise from the street from passing cars or the work of nearby enterprises, this is a significant reason to measure the noise level.
Neighbors can also interfere with the normal life of the residents of the house. If neighbors constantly emit noise that interferes with life and may exceed the permissible noise level in the apartment, you can order an examination and use its results when drawing up a lawsuit. The source of such noise can be loud music, TV, conversations, repair work, etc. For example, the crying of a child has an average noise level of 80 decibels, which is 25 decibels more than is acceptable during the day and 35 decibels more than the norm for night time. Focusing on such indicators, you can roughly determine what level of noise is unacceptable.
By law, noise at night should not exceed 30 dB (noise from the rustle of leaves or the ticking of a clock). However, what if the neighbors do not comply with the regime and interfere with normal sleep and rest? Read about ways to deal with such troublemakers in the article on our website https://potrebexpert.online/6301-sposoby-borby-s-sosedyami-kotorye-shumyat-nochyu
1. No-way variant of technical systems
The composition of such NAC TS includes:
— laser systems;
— electronic stethoscopes;
— audiovisual control systems.
A. Laser systems.
On the windows of the controlled room under
some angle is directed thin,
well focused beam of light
invisible range, usually infrared.
As the window panes vibrate in
according to changes in sound
indoor pressure, reflection angle
outgoing beam turns out to be
modulated by sound waves.
The beam reflected from the glass is captured
receiver that converts
it into an electrical signal, filters,
amplifies and reproduces
direct audio control with
using microphones.
Usually laser systems consist of two
devices that look like small
telescopes that are mounted on
tripods. The first device is
beam-forming laser transmitter
laser and allowing with the help of optical
system (lens) to focus it
on the selected window. The second device is
This is an optoelectronic reflective receiver.
beam that performs all the necessary
conversion and containing connectors
for simultaneous connection
microphones and tape recorder.
Infrared radiation even in inclement weather
weather is slightly absorbed in
atmosphere, so the range
laser systems is 200-300 meters.
In some situations (controlled room
located on the upper floors of the building,
windows are blocked by trees, etc.)
extremely difficult to find cover
to install the system, which is
disadvantage systems data.
important tactical dignityapplication of laser systems is
low probability of detection.
Laser systems are the most expensive
intercepting devices.
B. Electronic stethoscopes.
Designed for audio control
premises through structural elements:
doors, walls, ceilings, airframes
devices, etc.
Stethoscopes are made up of:
- highly sensitive contact
microphone (electret, piezoelectric),
perceiving sound vibrations
structural element frequency and
converting them into electrical
signal;
- an electronic unit that amplifies
signal;
- Microphones for direct
audio control.
The system may also include
information transmission channel.
The microphone is attached with a vacuum
suction cups or special paste, good
conducting sound waves. Stethoscopes
provide eavesdropping
through separating surfaces with a thickness
up to 60 centimeters. Best Results
- for metal and concrete barriers.
Somewhat worse - with wooden and
brick.
One of the largest manufacturers
electronic stethoscopes is a firm
PK ELECTRONIC. Via PK845-SS productscan be easily monitored through
windows, doors or concrete walls
70 cm.
filters, you can catch the conversation and
the ticking of an explosive clock
devices. electret microphone
supplied with 50-500 m cable —
at the request of the customer. When
insufficient cable length, device
has a remote control. slightest
sound waves are picked up
developed receptor and are enhanced
25,000 times built-in amplifier, becoming
heard through the loudspeaker or
headphones. The amplifier can be constantly
adjust to different types of walls
(material and thickness). Receptor attaches
to the wall with special cement included
in the scope of delivery. Thickness of cement
layer also affects the sensitivity:
between the wall and the receptor should be
about 3-5 mm if the wall is thin and only
1-2mm if the wall is thick.
B. Technical audiovisual systems
control.
The use of systems does not involve
placement of any technical
elements indoors, but requires
through hole with a diameter of 8-10 mm in
wall or ceiling of a building.
A special probe is inserted through them -
metal tube with a diameter of 6-10 mm,
at the end of which are subminiature
lens with an image field angle of 80-100
degrees and a sensitive microphone.
Visual observation is carried out using
eyepiece located on the opposite
end of the probe, and acoustic observation
- with the help of an amplifier and microphones.
In some system modifications
audiovisual control is provided
eyepiece adapter
video and medium format cameras, and
it is also possible to connect a tape recorder
to the electronic unit.
Audiovisual control systems, as
usually used to organize
short-term observation.
