ISO 3382-3:2012 音響  —  部屋の音響パラメータの測定  —  パート3：オープンプランオフィス | ページ 6

3.1

spatial sound distribution of the A-weighted sound pressure level of speech

curve which shows how the A-weighted sound pressure level decreases as a function of the distance from the sound source emitting noise with the sound power spectrum of normal speech

3.2

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: This definition is an application of DL₂ defined in ISO 14257, but using the spectrum of normal speech and A-weighting over the whole frequency range. The spatial decay is not determined for individual octave bands.

3.3

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 4,0 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.

3.4

speech transmission index

STI

physical quantity representing the transmission quality of speech with respect to intelligibility

[SOURCE: IEC 60268-16:2011]

3.5

spatial sound distribution of the speech transmission index

curve which shows how the speech transmission index decreases from a reference sound source when distance increases

3.6

distraction distance

r_D

distance from speaker where the speech transmission index falls below 0,50

Note 1 to entry: Distraction distance is expressed in metres.

Note 2 to entry: Above the distraction distance, concentration and privacy start to improve rapidly (see References [8] [14]).

3.7

privacy distance

r_P

distance from speaker where the speech transmission index falls below 0,20

Note 1 to entry: Privacy distance is expressed in metres.

Note 2 to entry: Above the privacy distance, concentration and privacy are experienced very much the same as between separate office rooms (see References [8] [14]). STI values less than 0,20 are difficult to achieve in offices with poor speech privacy or small volume.

3.8

background noise level

L_p,B

sound pressure level in octave bands present at the workstation during working hours with people absent

Note 1 to entry: Background noise here means all such continuous sounds, which are not caused by people, e.g. heating, ventilation and air conditioning (HVAC) devices, environmental traffic noise, office equipment or a sound-masking system.