ISO 22955:2021 音響—オープンオフィススペースの音響品質 | ページ 6

3.1.1

目標値

状況を評価し、それに基づいて行動するために指標として設定される値

注記 1: 目標値への準拠は、この文書の要件ではありません。

3.1.2

必要な値

目標とする値

注記 1: 必要な値への準拠は、このドキュメントの要件です。

3.2.1

office

space where professional or administrative duties are performed

3.2.2

open-plan space

open-plan office

open space

shared space

workspace designed to accommodate multiple persons working without full separation between workstations

Note 1 to entry: The activities performed in an open-plan space can be discriminated: telephone, administrative work, etc.

3.2.3

workstation

position occupied to perform a task

3.2.4

workspace

open-plan space (3.2.2) , in which the workstations required to perform the activity are distributed

3.2.5

open-plan space area

total floor area, in square metres, of the open plan office

3.2.6

occupancy ratio

number of workstations occupied at a given time, divided by the total number of workstations

3.2.7

divider and screen

vertical partition, which partially divides the space and crosses the virtual line joining a noise source (e.g. someone speaking) and a reception point

3.2.8

screen fixed to the worktop

low divider

vertical item held by the worktop, used to delimit the workstation visually, reduce noise between workstations and can provide acoustic absorption close to users

Note 1 to entry: This screen can be installed in front or to the side of the user.

3.2.9

activity

physical actions and interactions that people undertake in the workplace environment

3.3.1

intelligibility

percentage of speech understood

3.3.2

noise disturbance

physiological (sensory) and psychological (perceptual and cognitive) process incurred by intrusive unwanted sound, which tends to create a situation of unease or discomfort by disturbing the concentration of an individual

Note 1 to entry: Among others, it depends on physical factors such as noise level, frequency and repeatability of the acoustic phenomena, to which the individual is subjected. Different sources cause different disturbances. It is noted that other non-acoustic factors can affect noise disturbance. Generally, individuals' sensitivity to noise disturbance is not the same.

3.3.3

discretion

situation obtained when an effort is required to understand the content of a conversation emitted from a neighbouring workstation

Note 1 to entry: Under these conditions, conversation is not a cause of distraction. A high level of discretion reflects low intelligibility and rapid decrease in the energy coming from the source workstation.

3.3.4

Lombard effect

phenomenon of a person unconsciously altering his/her way of speaking (adaptation of fundamental frequency, sound level and articulation) to make up for the presence of surrounding noise and to be better understood by his/her conversation partners

3.3.5

social and welfare spaces

spaces designed specifically for social interaction

Note 1 to entry: These type of spaces may not be compatible with operation of open plan offices, if the spaces are physically connected, used simultaneously and without regard to normal working operations.

Note 2 to entry: Game areas utilising table tennis, table football or with gym equipment can be very disruptive to office working and need to be carefully managed and/or physically separated.

3.3.6

signal-to-noise ratio

arithmetical difference between the signal level and the disturbing noise level

Note 1 to entry: The signal-to-noise ratio is given in dB.

3.4.1

workstation noise level

L_Aeq,T

Note 1 to entry: The noise level at the workstation is measured with normal activity in the room (with office equipment operating and a human presence).

Note 2 to entry: The measurement is performed as described in Annex E.

3.4.2

spatial decay rate of speech

D_2,S

rate of spatial decay of A-weighted sound pressure level of speech per distance doubling

Note 1 to entry: Spatial decay rate of speech is expressed in decibels (dB).

Note 2 to entry: S refers to"speech".

[SOURCE: ISO 3382-3:2012, modified — Original Note deleted, new Notes to entry 1 and 2 were added.

3.4.3

reverberation time

T_r

time, in seconds, required for the existing noise level inside a room to decrease by 60 dB, when the noise source is instantly interrupted

Note 1 to entry: Reverberation time is determined by octave bands for frequencies from 125 Hz to 4000 Hz and is defined in ISO 3382-2:2008.

Note 2 to entry: In this document, Engineering level accuracy should be used for the measurement of reverberation time according to ISO 3382-2.

Note 3 to entry: Microphone positions should be between 2 m and 8 m from the sound source, while still respecting the minimum distance described in ISO 3382-2.

3.4.4

in situ acoustic attenuation of speech

D_A,S

difference, in decibels, between an A-weighted speech source spectrum at 1 m from an omni-directional source in the free field and the A-weighted sound pressure level at a reception point

Note 1 to entry: Calculation method is detailed in Annex A.

Note 2 to entry: S refers to"speech".

3.4.5

A-weighted sound pressure level of speech at a distance of 4 m

L_{p,A,S,4 m}

nominal A-weighted sound pressure level of normal speech at a distance of 4 m from the sound source

Note 1 to entry: The measurement position does not need to be located at this distance from the sound source. L_{p,A,S,4 m} is obtained using a linear regression line from the spatial sound distribution of the A-weighted sound pressure level (SPL) of speech.

Note 2 to entry: S refers to"speech".

[SOURCE: ISO 3382-3:2012, modified — Note to entry 2 was added.

3.4.6

A/S_Floor

equivalent absorption area divided by the floor surface area

3.4.7

weighted standardized level difference

D_nT,w

single indicator constituted by the value at 500 Hz, expressed in decibels, of a reference curve, applied to standardized level difference, D_nT

Note 1 to entry: The reference curve is as defined in ISO 717-1.

Note 2 to entry: The standardized level difference, D_nT , is defined by ISO 16283-1 as the difference between the sound pressure levels created by a source in one of the rooms affected by the reverberation time T in the receiving room applied to a reference reverberation time T₀.

3.4.8

insulation from internal airborne noise

D_nT,A

sum of the weighted standardized level difference (3.4.7) and matching factor C

Note 1 to entry: The matching factor C is defined in ISO 717-1.

3.4.9

normalized flanking level difference

D_n,f

Note 1 to entry: This quantity is expressed in decibels.

Note 2 to entry: For clarity, the term D_n,f is used when only one flanking path determines the sound transmission (such as with suspended ceilings) and the term D_n,f,ij is used when only one specified transmission path ij out of several paths is considered (such as with structure-borne sound transmission on junctions of three or four connected elements).

[SOURCE: ISO 10848-2:2017, 3.1]

3.4.10

maximum sound level

L_max

Maximum A weighted sound level, during a measurement period or a noise event.