Technical Report: What is a Sound Level Meter? (15)

The main laws in Japan related to noise and their contents are as follows. Based on these, government ordinances and local ordinances are established, and each is under the jurisdiction of a different supervisory agency. In practice, pollution-related matters are handled by the "Pollution Control Division," "Environmental Health Division," or "Citizen Life Division" of each prefecture and municipality, while matters related to occupational safety and health in companies are handled by the labor standards inspection offices of each prefecture and the national government.

Basic Environmental Law (Environmental Standards) (Ministry of the Environment)
- Standards for Environmental Noise
- Standards for aircraft noise
- Standards concerning Shinkansen railway noise
- Standards for noise from conventional railway lines
Noise Regulation Law (Ministry of the Environment)
- Standards concerning noise from specific facilities and factories
- Standards concerning noise from specific construction work
- Standards concerning automobile traffic noise and automobile noise
- Matters concerning late-night operations and noise from loudspeakers, etc. (Standards are determined by municipal ordinances)
Environmental Impact Assessment Law (Ministry of the Environment)
Fire Service Act Enforcement Regulations (Fire and Disaster Management Agency, Ministry of Internal Affairs and Communications)
- Standards for alarm sounds, etc.
Industrial Safety and Health Regulations (Ministry of Health, Labour and Welfare)
- For information regarding workplace noise measurement (according to the Industrial Safety and Health Regulations), please refer to this page on the Ministry of Health, Labour and Welfare website.
- Please refer to this Ministry of Health, Labour and Welfare page for the "Guidelines for Preventing Noise-Related Health Problems" (revised April 2023).
Large-Scale Retail Store Location Law (Ministry of Economy, Trade and Industry)

The Basic Environment Law was amended in April 1999, and parts of the Noise Regulation Law were amended in April 2000. Furthermore, the Environmental Assessment Law came into effect in June 1999.

In addition, the "Recommendations for Permissible Concentrations, etc." published by the Japan Society for Occupational Health sets out "permissible noise standards" for use as a guide to prevent health hazards to workers caused by environmental factors in the workplace.

In Japan's Basic Environment Law, the ultimate goal is set for the level to which policies should be implemented to maintain air, water, soil, and noise levels, as desirable standards for protecting human health and preserving the living environment.
Based on the provisions of Article 16, Paragraph 1 of the Basic Environment Law, the "Environmental Standards for Noise" were announced as desirable standards to be maintained in order to preserve the living environment and protect human health, and were implemented from April 1, 1999.
This can be considered a target for improving environmental pollution caused by noise, in other words, a noise prevention target. Other standards, such as "Environmental Standards for Aircraft," "Environmental Standards for Shinkansen Railways," and "Guidelines for Noise Countermeasures during the Construction or Major Improvement of Conventional Railways," remain unchanged. Please refer to the Act for further details.

Table 13-1 "Areas other than those facing roads"

Regional types	Reference value
Regional types		Daytime	night time
AA	Below 50 decibels	Below 40 decibels
A and B	55 decibels or less	45 decibels or less
C	Below 60 decibels	Below 50 decibels
Environmental standards shall be as listed in the standard value column of the following table for each type of region and time period, and the regions to which each type applies shall be designated by the prefectural governor. The time divisions are defined as daytime from 6:00 AM to 10:00 PM and nighttime from 10:00 PM to 6:00 AM the following day. Areas to which AA should be applied are those requiring particular tranquility, such as areas where medical facilities, social welfare facilities, etc., are concentrated. The area to which A applies shall be an area used exclusively for residential purposes. Areas to which B applies shall be areas primarily used for residential purposes. Areas to which C applies are those that contain a considerable number of residences and are also used for commercial, industrial, and other purposes.

Table 13-2 "Areas facing roads"

Regional divisions	Reference value
Regional divisions		Daytime	night time
Area A: Areas facing roads with two or more lanes.	Below 60 decibels	55 decibels or less
Area B that faces a road with two or more lanes and Area C: Areas facing roads with lanes	Below 65 decibels	Below 60 decibels
A lane is a strip-shaped section of roadway that has a certain width necessary for a line of vehicles to travel safely and smoothly.

Table 13-3 "Space adjacent to roads carrying main traffic" (Special Case)

Reference value
Daytime	night time
Below 70 decibels	Below 65 decibels
If it is determined that residents in individual residences or other buildings primarily keep the windows on the side most susceptible to noise closed, the standards for noise transmitted indoors (45 decibels or less during the day and 40 decibels or less at night) may be applied.

The reference values for the above environmental standards shall be those obtained when evaluated using the following method.

The evaluation shall be based on the noise level affecting individual residences, and shall be evaluated based on the noise level on the noise-sensitive side of the building used for residential purposes. In this case, the standard for noise transmitted into the building shall be evaluated by subtracting the sound insulation performance value of the building from the noise level on the noise-sensitive side of the building.
The noise evaluation method shall be based on the equivalent sound level, and the evaluation shall, in principle, be based on the equivalent sound level over the entire duration for each time period.
The evaluation period shall be selected to reflect the average noise levels throughout the year.
When measurements are taken for evaluation purposes, the noise level measurement method specified in JIS Z 8731 shall be used as a general rule. If the effect of reflection from the building in question cannot be ignored, measurements shall be taken at a location where this effect can be avoided, and if this is difficult, appropriate measures shall be taken, such as correcting the measured value. Furthermore, if the necessary measurement time cannot be secured, the noise level may be estimated from conditions such as road traffic volume instead of taking measurements.
Factories and businesses that generate significant noise, construction sites, airports, railway premises, and similar locations will be excluded from the measurement locations.
These environmental standards do not apply to aircraft noise, railway noise, and construction noise.

For areas other than those facing roads, the evaluation shall, in principle, be conducted by selecting a point that is considered representative of the noise level in each designated area.
For areas facing roads, the evaluation shall, in principle, be conducted by determining the number of houses and the percentage of houses that exceed the environmental standards specified in "1." for each designated area.

Table 13-4 "Aircraft Noise"

Regional types	Reference value (WECPNL) dB or less
I. Areas used exclusively for residential purposes	70
II. Areas other than those listed in I, where it is necessary to preserve normal living conditions.	75
This does not apply to airports with 10 or fewer takeoffs and landings per day, or to areas surrounding airports located on remote islands. Noise measurement method As a general rule, measurements are taken for 7 consecutive days, recording the peak noise level and number of units that are 10 dB or more above the background noise level. The WECPNL for each day is calculated using the following formula, and all values are power-averaged. The test will be conducted outdoors at a location recognized as representative of aircraft noise levels. A period is selected that is considered representative of aircraft noise, taking into account aircraft flight conditions and weather conditions such as wind direction. Use the A-weighting and slow setting on the sound level meter.

Regarding aircraft noise, following a report from the Central Environment Council on June 29, 2007, some of the environmental standards for aircraft noise were revised and officially announced on December 17, 2007.

Table 13-5 "Aircraft Noise" (Revised in 2007)

Regional types	Reference value (L_den) dB or less
I. Areas used exclusively for residential purposes	57
II. Areas other than those listed in I, where it is necessary to preserve normal living conditions.	62
This also applies to airports with an average of 10 or fewer takeoffs and landings per day. Noise measurement method The equivalent sound level for one day was evaluated by weighting evening noise and nighttime noise. For the evaluation, L_den was calculated for each day using equation (1), and the power average was calculated for L_den for all measurement days using equation (2). however, i, j and k This means that the observed sample in each time period i number one, j second and k Say the number, L_{AE, di} This refers to the period from 7 AM to 7 PM. i The second L_AE, L_{AE, ej} This refers to the period between 7 p.m. and 10 p.m. j The second L_AE, L_{AE, nk} This refers to the period from midnight to 7:00 AM and from 10:00 PM to 12:00 AM. k The second L_AE It refers to, T₀ This refers to the normalization time (1 second), T This refers to the duration of one observation day (86,400 seconds). N This refers to the number of days of measurement. L_{den, i} This refers to the period of the measurement day. i Day 1 of measurement L_den It refers to. (reference) Internationally, L_den is adopted in EU directives and by many countries, including France and Denmark. Similar indicators based on equivalent noise levels are also used by countries such as the United States and Austria. The test will be conducted outdoors at a location recognized as representative of aircraft noise levels. A period is selected that is considered representative of aircraft noise, taking into account aircraft flight conditions and weather conditions such as wind direction. Use the A-weighting and slow setting on the sound level meter.

Regional types

Reference value (L_den)
dB or less

I. Areas used exclusively for residential purposes

II. Areas other than those listed in I, where it is necessary to preserve normal living conditions.

This also applies to airports with an average of 10 or fewer takeoffs and landings per day.
Noise measurement method
- The equivalent sound level for one day was evaluated by weighting evening noise and nighttime noise. For the evaluation, L_den was calculated for each day using equation (1), and the power average was calculated for L_den for all measurement days using equation (2).

however, i, j and k This means that the observed sample in each time period i number one, j second and k Say the number, L_{AE, di} This refers to the period from 7 AM to 7 PM. i The second L_AE, L_{AE, ej} This refers to the period between 7 p.m. and 10 p.m. j The second L_AE, L_{AE, nk} This refers to the period from midnight to 7:00 AM and from 10:00 PM to 12:00 AM. k The second L_AE It refers to, T₀ This refers to the normalization time (1 second), T This refers to the duration of one observation day (86,400 seconds).

N This refers to the number of days of measurement. L_{den, i} This refers to the period of the measurement day. i Day 1 of measurement L_den It refers to.

(reference)
Internationally, L_den is adopted in EU directives and by many countries, including France and Denmark. Similar indicators based on equivalent noise levels are also used by countries such as the United States and Austria.

The test will be conducted outdoors at a location recognized as representative of aircraft noise levels.
A period is selected that is considered representative of aircraft noise, taking into account aircraft flight conditions and weather conditions such as wind direction.
Use the A-weighting and slow setting on the sound level meter.

Table 13-6 "Shinkansen Railway Noise"

Regional types	Reference value dB or less
I. Areas primarily used for residential purposes	70
II Areas other than those used for commercial and industrial purposes, etc., where it is necessary to preserve the normal life of the people.	75
Applies between 6:00 AM and 12:00 PM. The regions to which each category applies are designated by the prefectural governor. Noise measurement method For 20 trains passing consecutively, including both uphill and downhill trains, the peak noise level is read for each passing train, and the top half are power-averaged. (Noise measurement method) In addition to locations recognized as representative of Shinkansen railway noise, measurements were taken outdoors at locations where Shinkansen railway noise is a problem, generally at a height of 1.2 m above the ground. Avoid periods of unusual weather conditions and times when train speeds are expected to be lower than normal. Use the A-weighting and slow setting on the sound level meter.