ISO 16283-1:2014 音響—建物および建物要素の遮音の現場測定—パート1：空中遮音 | ページ 6

3.1

energy-average sound pressure level in a room

L

ten times the common logarithm of the ratio of the space and time average of the squared sound pressure to the square of the reference sound pressure, with the space average taken over the central zone of the room where the direct radiation from any loudspeaker or the nearfield radiation from the room boundaries has negligible influence

Note 1 to entry:L is expressed in decibels.

3.2

corner sound pressure level in a room

L_Corner

ten times the common logarithm of the ratio of the highest time average squared sound pressure from the set of corner measurements to the square of the reference sound pressure, for the low-frequency range (50, 63, and 80 Hz one-third octave bands)

Note 1 to entry:L_Corner is expressed in decibels.

3.3

low-frequency energy-average sound pressure level in a room

L_LF

ten times the common logarithm of the ratio of the space and time average of the squared sound pressure to the square of the reference sound pressure in the low-frequency range (50, 63, and 80 Hz one-third octave bands) where the space average is a weighted average that is calculated using the room corners where the sound pressure levels are highest and the central zone of the room where the direct radiation from any loudspeaker or the nearfield radiation from the room boundaries has negligible influence

Note 1 to entry:L_LF is expressed in decibels.

Note 2 to entry:L_LF is an estimate of the energy-average sound pressure level for the entire room volume.

3.4

reverberation time

T

time required for the sound pressure level in a room to decrease by 60 dB after the sound source has stopped

Note 1 to entry:T is expressed in seconds.

3.5

background noise level

measured sound pressure level in the receiving room from all sources except the loudspeaker in the source room

3.6

fixed microphone

microphone that is fixed in space by using a device such as a tripod so that it is stationary

3.7

mechanized continuously-moving microphone

microphone that is mechanically moved with approximately constant angular speed in a circle, or is mechanically swept along a circular path where the angle of rotation about a fixed axis is between 270° and 360°

3.8

manually-scanned microphone

microphone attached to a hand-held sound level meter or an extension rod that is moved by a human operator along a prescribed path

3.9

manually-held microphone

microphone attached to a hand-held sound level meter or a rod that is hand-held at a fixed position by a human operator at a distance at least an arm’s length from the trunk of the operator’s body

3.10

partition

total surface of the separating partition between the source and receiving rooms

Note 1 to entry: For two rooms which are staggered vertically or horizontally, the total surface of the separating partition is not visible from both sides of the partition; hence it is necessary to define the partition as the total surface.

3.11

common partition

part of the partition that is common to both the source and receiving rooms

3.12

level difference

D

Note 1 to entry:D is expressed in decibels.

3.13

standardized level difference

D_nT

Note 1 to entry:D_nT is expressed in decibels.

Note 2 to entry: The level difference is referenced to a reverberation time of 0,5 s because in dwellings with furniture the reverberation time has been found to be reasonably independent of volume and frequency and to be approximately equal to 0,5 s. With this standardization, D_nT is dependent on the direction of the sound transmission if the source and receiving rooms have different volumes; D_nT will be higher when the test is carried out from a smaller source room to a larger receiving room compared to the reverse situation. For this reason, regulations that require testing to show compliance with a minimum standard of airborne sound insulation usually require that the smaller room is used as the receiving room so that the lowest D_nT values are measured.

Note 3 to entry:D_nT provides a straightforward link to the subjective impression of airborne sound insulation.

3.14

apparent sound reduction index

R'

Note 1 to entry:R' is expressed in decibels.

Note 2 to entry: In general, the sound power transmitted into the receiving room consists of the sum of several components from different elements (walls, floor, ceiling etc.).

Note 3 to entry:R' can be used to compare field measurements with laboratory measurements of the sound reduction index, R. In comparison to D_nT it has a weaker link to the subjective impression of airborne sound insulation.

Note 4 to entry: When R' is determined in the 50 Hz, 63 Hz and 80 Hz bands using the low-frequency procedure the link to sound power in Formula (3) is not exact.

3.15

equivalent absorption area

A

Note 1 to entry:A is expressed in square metres.