Technical Report: What is a sound level meter?

The regulation on noise generated by industrial activities and the permissible limits for automobile noise was promulgated on June 10, 1968, and came into effect on December 1 of the same year.

Article 1 states that the purpose of this law is "to regulate the considerable range of noise generated by business activities in factories and workplaces, as well as construction work, and to establish permissible limits for automobile noise, thereby preserving the living environment and contributing to the protection of public health." It regulates "specific factories and related regulations," "regulations concerning specific construction work," and "permissible limits for automobile noise, etc."

"The 'Permissible Limits for Automobile Noise' refers to the 'permissible limits for the magnitude of automobile noise' and includes an order that establishes limits for automobile noise within designated areas. These regulations were revised and came into effect on April 1, 2000. Below is an excerpt from the noise regulation law for your reference. For more details, please refer to this law and related local ordinances established based on it."

Table 13-7 "Noise Generated in Specific Factories and Similar Environments"

division of areas	division of time			Remarks
daytime	morning and evening	nighttime
(7 AM, 8 AM ~ 6 PM, 7 PM, 8 PM)	(5, 6 to 7, 8 AM) (6, 7, 8 to 9, 10, 11 PM)	(9, 10, 11 PM - 5, 6 AM the next day)
(Type 1 Area) To preserve a good residential environment, areas that particularly require the maintenance of tranquility.	below 45 to 50 dB	below 40 to 45 dB	40 to 45 dB	The standard value is the noise level at the factory site boundary. The division of time is determined according to the lifestyle of the region.
(Category 2 Area) Designated for residential use, requiring the maintenance of tranquility in the area.	50 to 60	45 to 50	40 to 50
(Type 3 Zone) A zone that is provided for residential use along with commercial and industrial uses, and it is necessary to prevent noise generation in order to preserve the living environment of the residents in that zone.	60 to 65	55 to 65	50 to 55
(Type 4 Area) An area primarily used for industrial purposes, where it is necessary to prevent significant noise generation in order to avoid deteriorating the living environment of the residents within that area.	65 to 70	60 to 70	55 to 65

Table 13-8 "Noise Generated During Specific Construction Activities"

types of work		regulatory standards	condition				Remarks
types of work		regulatory standards	Nighttime or late-night work	daily working hours	work period	Sunday Sunday, and other holidays	Remarks
1. Work using a pile driver, pile extractor, or pile driving and extraction machine.	Excluding the use of the monken. Excluding the press-in type pile driving and pile extraction machines. Excluding the operation that shares the pile driver with the earth auger.	below 85 dB	Prohibited in area ① from 7 AM to 7 AM the next day, and in area ② from 10 PM to 6 AM the next day.	Area 1: 10 hours, Area 2: 14 hours	Consecutive 6 days in the same place.	prohibit	The area of ① is generally within 80 meters of the grounds of Type 1, Type 2, and Type 3 zones, as well as schools, daycare centers, hospitals, clinics that accommodate patients, libraries, and special nursing homes. Area ② is an area other than Area ①. Exemptions from application are available under conditions such as emergencies and danger prevention.
2. Work using a nail gun.
3. Work using a rock drill.	In work where the work site moves continuously, it is limited to work where the maximum distance between two locations in one day does not exceed 50 meters.
4. Work using an air compressor.	Only power sources other than electric motors with a rated output of 15 kW or more are permitted, excluding work using rock drilling machines.
5. Work carried out by establishing a concrete plant or asphalt plant.	Only those with a kneading capacity of 0.45 m ³ or more for the kneader are allowed. Only those with a kneading weight of 200 kg or more for the kneader are allowed. Excluding work done by setting up a concrete plant to produce mortar.
Noise measurement shall be conducted using a sound level meter that meets the conditions of Article 71 of the Measurement Act. In this case, the frequency correction circuit shall use the A characteristic, and the dynamic characteristic shall be fast (Fast). The method for measuring noise will, for the time being, be based on the noise level measurement method specified in the Japanese Industrial Standards Z 8731 (1983 edition, former JIS), and the determination of the noise level will be as follows. If the reading of the sound level meter does not fluctuate or fluctuates little, that reading should be taken as the valid measurement. If the readings from the sound level meter fluctuate periodically or intermittently, and the maximum value of those readings remains generally constant, then the average of the maximum values for each fluctuation should be taken. If the readings of the sound level meter are irregular and fluctuate significantly, use the upper value of the 90 percent range of the measurements. If the readings of the sound level meter fluctuate periodically or intermittently, and the maximum reading is not constant, use the upper value of the 90 percent range of the maximum reading for each fluctuation.

The reference value changed from L ₅₀ to L _Aeq on April 1, 2000.

Table 13-9 Request limit values related to automobile noise
(Cabinet Order establishing limits for automobile noise in designated areas)

division of areas

division of time

daytime

nighttime

an area facing a road with one lane in either area a or area b

65 dB

55 dB

an area facing a road with two or more lanes

70 dB

65 dB

Area b, which faces a road with two or more lanes,
and area c, which faces a road with lanes.

75 dB

70 dB

In the areas listed in the above table, the limits concerning areas adjacent to roads that carry main traffic (for roads with two lanes or fewer, this refers to a range of 15 meters from the boundary of the road property; for roads with more than two lanes, it refers to a range of 20 meters from the boundary of the road property) shall be set at 75 dB during the day and 70 dB at night, regardless of the above table.

In areas where facilities that particularly require quietness, such as schools and hospitals, are gathered, the governor of the prefecture, the mayor, and the prefectural planning committee can consult and establish regulations.
Areas a, b, and c refer to the regions designated by the governor of the prefecture as specified below.

a area	an area exclusively provided for residential use
b area	an area primarily designated for residential use
Area C	An area used for a considerable number of residences, as well as for commercial, industrial, and other purposes.

daytime	6 AM to 10 PM
nighttime	10 PM to 6 AM the following day

Main transportation: expressways, national highways, motorways, prefectural roads, and municipal roads with four or more lanes.

Noise measurements should be conducted at the boundary line of the road property when there are residences, hospitals, schools, or similar facilities adjacent to the road. If the residences are located at a distance from the road, measurements should be taken at a point where the noise level can be accurately assessed at the residences. The height at which measurements are taken should be at the position where noise is most problematic for the preservation of the living environment in the vertical direction. Intersections should be avoided.
The measurement will evaluate the equivalent noise level based on 3 days recognized as representative of the automobile noise situation during a continuous 7-day period. The magnitude of the noise will be determined by averaging the measured values over the entire time period, based on the principle of 3 days.
Noise measurement shall be conducted using a sound level meter that meets the conditions of Article 71 of the Measurement Law, and measurements shall be taken at a position that avoids the influence of reflections from buildings, according to the measurement methods specified in JIS Z 8731. If it is not possible to avoid such influences, the measured values shall be adjusted accordingly. If there are influences from noise other than automobile noise, these influences shall also be considered when adjusting the measured values.

The "Permissible Limits for Automobile Noise Levels (Notification by the Environmental Agency)" based on the Noise Regulation Act was revised in February 2000, resulting in a reduction of 1 dB to 3 dB for acceleration noise, 1 dB to 6.1 dB for steady-state noise, and 5 dB to 8 dB for close exhaust noise compared to previous values. Additionally, the methods for measuring noise for vehicles subject to strengthened regulations have also been changed. For details, see Table 13-10.

Table 13-10 Permissible Limit Values for Automobile Noise Levels (Ministry of the Environment Notification, 2000)

types of automobiles			the permissible limit of automobile noise volume
types of automobiles			steady driving noise	close exhaust noise	acceleration driving noise
Ordinary cars, small cars, and light vehicles (excluding passenger vehicles designed primarily for use with a seating capacity of ten or fewer and motorcycles).	Vehicles with a total weight exceeding 3.5 tons and a maximum engine output exceeding 150 kW.	A vehicle equipped with a power transmission device that can transmit power to all wheels, used for towing semi-trailers and for crane operations.	83 dB	99 dB	82 dB
		A vehicle equipped with a power transmission device that can transmit power to all wheels, excluding those used for towing semi-trailers and those used for crane operations.	82 dB	99 dB	81 dB
	Vehicles with a total weight exceeding 3.5 tons and a maximum engine output of 150 kW or less.	A power transmission device equipped with a structure that can transmit power to all wheels.	80 dB	98 dB	81 dB
		anything other than those equipped with a power transmission device that can transmit power to all wheels.	79 dB	98 dB	80 dB
	vehicles with a total weight of 3.5 tons or less		74 dB	97 dB	76 dB
Ordinary automobiles, small cars, and light vehicles (excluding motorcycles) that are primarily used for passenger transport and have a seating capacity of ten or fewer.	those having an engine at the rear of the vehicle.		72 dB	100 dB	76 dB
	Things other than those having an engine at the rear of the vehicle.		72 dB	96 dB	76 dB
Small motor vehicle (limited to two-wheeled vehicles.)			72 dB	94 dB	73 dB
Light motor vehicle (limited to motorcycles).			71 dB	94 dB	73 dB
Type 1 motorized bicycle (referring to the Type 1 motorized bicycle as defined in Article 1, Section 2 of the regulations; the same applies hereafter.)			65 dB	84 dB	71 dB
Type 2 motorized bicycle (referring to the Type 2 motorized bicycle as defined in Article 1, Section 2 of the regulations; the same applies hereafter.)			68 dB	90 dB	71 dB

The Environmental Impact Assessment Law, based on the Basic Environmental Law, recognizes the critical importance of conducting environmental impact assessments in advance by businesses undertaking projects such as land alteration and the establishment of new facilities, clarifying the responsibilities of the state and others. It establishes procedures to ensure that environmental impact assessments are conducted appropriately and smoothly, and aims to reflect the results of these assessments in project content, taking measures to ensure proper consideration for environmental conservation. The ultimate goal is to contribute to securing the health and cultural living standards of current and future citizens. This law was enacted in June 1999. Environmental assessment was institutionalized in the United States in 1969, and in response to the increasing global environmental pollution issues, many countries are advancing the legislation of similar laws.

What is an environmental impact assessment?

Conduct investigations, predictions, and evaluations regarding the environmental impact of the project in advance, by examining each component of the environment (scoping).
During the execution of the project, measures and considerations will be taken to ensure that environmental conservation related to the project is maintained.
Comprehensive evaluation of environmental impacts after implementation and in the case where those measures have been taken.

It stipulates a system for selecting projects that are large in scale and may have significant environmental impacts, which the government must implement or authorize, mandating that environmental impact assessments be conducted for projects above a certain scale ("Type 1 projects"). It also defines projects that have a scale similar to Type 1 projects ("Type 2 projects") and discusses the necessity of conducting environmental impact assessments based on the differences in each project and region.

Type 1 projects include the construction and improvement of expressways, general national roads, and large-scale forest roads; the construction of power generation facilities and dams, as well as the construction and improvement of weirs; the construction and improvement of railways and airports; the establishment or modification of final disposal sites for general and industrial waste; land reclamation and drainage projects; land readjustment; the development of industrial parks; new residential urban development; new urban infrastructure development; and the development of distribution business parks.

In conducting an environmental impact assessment, it is stipulated to determine effective survey items and methods for advancing the evaluation (scoping). The business plan will be advertised and opinions from residents will be widely accepted. Our company has prepared environmental noise prediction software "SoundPLAN" for noise.

Table 13-10 Summary of Noise Evaluation Metrics in Japan's Environmental Noise Measurement

Type	evaluation metric	law	Citation of JIS Z 8731
road traffic noise	Equivalent noise level L_Aeq	Basic Environmental Law	new
Railway (Shinkansen) noise	L_A (Slow) peak value power average		old
railway (conventional line) noise	Find L_Aeq from L_AE
aircraft noise	WECPNL L_A（Slow）
Aircraft noise (effective April 2013)	L_den (equivalent continuous noise level adjusted for time of day)		new
Noise from factories, business establishments, and construction sites	For steady noise, the indicated value L_A (Slow)	Noise Regulation Law	old
	For fluctuating noise: upper limit value of 90% range (L₅) < L_A (Fast) to be determined >
	In the case of intermittent noise: When the maximum value is constant, it refers to its average value. If the maximum value fluctuates, the upper limit of the 90% range (L₅) L_A (Slow) is obtained from the above.
automobile traffic noise	Equivalent noise level L_Aeq		new
automobile standalone noise	L_A (Fast)		new
Work environment noise	L_Aeq (Slow) equivalent noise level for 10 minutes	Labor Safety and Health Regulations	old