materials.absorbers.suspended_ceilings

Suspended ceilings in a reverberation room: EN 16487:2014.

EN ISO 354 measures the sound absorption of a specimen in a reverberation room and leaves a good deal to the laboratory: how big the specimen is, how it is mounted, how deep the air space behind it is. For a suspended ceiling those choices move the answer by more than the measurement uncertainty, so a product measured in two laboratories could be compared only by accident. This test code closes them.

What it fixes. A specimen area as close to 10,80 m2 as the product allows, test objects of 0,6 m by 0,6 m butted together with no seal in the joints between them, the exposed face level with the top of the mounting fixture and the joint between the specimen and that fixture taped, the edges at an angle to the room walls, and a mounting fixture of solid material with a surface density of at least 20 kg/m2. For the type E mounting that a suspended ceiling actually uses, it fixes the overall depth of construction at 200 mm for the measurement that CE marking rests on, the substructure at no more than 30 mm wide and 50 mm deep on a pitch of about 0,6 m, the support units under it at no more than 50 mm by 50 mm in cross-section and at least 1,2 m apart, and the deflection of the specimen at no more than 5 mm.

What it costs to ignore the air. 4.2.1 asks for test conditions under which the air-absorption correction

Δ α = \frac{4 V ( m _{2} - m _{1} )}{S}

of EN ISO 354 Formulae (8) and (9) stays under 0,05 at every frequency, with the relative humidity at 50 % or more. That correction is the difference between two measurements of the same room on two different days, and a dry room makes it large exactly where a ceiling absorbs most.

What it is worth. Table 1 is the reproducibility between European laboratories, from the round robin of Annex A: +/- 0,23 on the absorption coefficient at 125 Hz and 250 Hz, falling to +/- 0,10 at 1 kHz and 2 kHz, and +/- 0,08 on the weighted rating, with a coverage factor of 2,8 applied to the reproducibility standard deviation. The figures hold for a plane absorber with the type E mounting and for nothing else, which the clause says in as many words.

Read from BS EN 16487:2014.

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

air_absorption_correction

air_absorption_correction(
    *,
    volume_m3: float,
    specimen_area_m2: float,
    attenuation_with: ArrayLike,
    attenuation_empty: ArrayLike,
) -> NDArray[np.float64]

The correction 4.2.1 caps, as an absorption coefficient.

Δ α = \frac{4 V ( m _{2} - m _{1} )}{S}

the part of EN ISO 354 Formulae (8) and (9) that comes from the air rather than from the specimen. The two attenuation coefficients belong to the two measurements, with the specimen and empty, and the correction is their difference because everything else about the room cancels.

A room measured on two days of different humidity can carry more of this than the specimen carries of its own absorption at 4 kHz, which is why the clause caps it at AIR_CORRECTION_LIMIT and asks for 50 % relative humidity or more.

Parameters

Name	Description
`volume_m3`	$V$ of the reverberation room, in cubic metres.
`specimen_area_m2`	$S$ of the specimen, in square metres.
`attenuation_with`	$m_{2}$ per band, in reciprocal metres.
`attenuation_empty`	$m_{1}$ per band, in reciprocal metres.

Returns: $Δ α$ per band.

Raises

Exception	When
ValueError	For a non-positive volume or area, or coefficients that do not match band for band.

AIR_CORRECTION_LIMIT

Constant (float).

AIR_CORRECTION_LIMIT = 0.05

CEILING_UNCERTAINTY

Constant (mapping).

CEILING_UNCERTAINTY = {125.0: 0.23, 250.0: 0.23, 500.0: 0.11, 1000.0: 0.1, 2000.0: 0.1, 4000.0: 0.13}

CeilingSpecimenCheck

CeilingSpecimenCheck(
    area_m2: float,
    area_error_m2: float,
    mounting: str,
    depth_mm: float | None,
    deflection_ok: bool,
    substructure_ok: bool,
    fixture_ok: bool,
    supports_ok: bool,
    humidity_ok: bool | None,
    ce_marking_depth: bool,
    satisfied: bool,
)

Whether a test arrangement meets the printed limits of clause 4.

The verdict covers the limits clause 4 puts a number on and a measured arrangement can be held to: the mounting fixture of 4.1.1.1.6, the substructure profile of 4.1.1.2.3.4, the deflection of 4.1.1.2.3.5, the support units of 4.1.1.2.3.6 and, when it was given, the relative humidity of 4.2.2. Two figures are reported beside the verdict and kept out of it, because the clause does not make them a pass or a fail: the area error, since 4.1.1.1.1 asks for an area “as close to 10,80 m2 as possible”, and the CE marking depth, since 4.1.1.2.3.1 recommends 200 mm and requires it only of the data CE marking is compiled from.

Parameters

Name	Description
`area_m2`	The specimen area as built, in square metres.
`area_error_m2`	How far it sits from the 10,80 m2 the code aims at, reported and not judged.
`mounting`	The mounting letter the arrangement uses.
`depth_mm`	The overall depth of construction, in millimetres, for a type E mounting, or `None` for the others.
`deflection_ok`	Whether the deflection stays inside 5 mm.
`substructure_ok`	Whether the profile stays inside 30 mm by 50 mm.
`fixture_ok`	Whether the mounting fixture is heavy enough.
`supports_ok`	Whether the support units stay inside 50 mm by 50 mm in cross-section and, when their centre distance was given, stand at least 1,2 m apart.
`humidity_ok`	Whether every measurement was made at 50 % relative humidity or more, or `None` when no humidity was given.
`ce_marking_depth`	Whether the depth is the 200 mm the CE marking data rests on, reported and not judged.
`satisfied`	Whether every judged limit holds: the fixture, the substructure, the deflection, the supports and, when it was given, the humidity.

check_ceiling_specimen

check_ceiling_specimen(
    *,
    area_m2: float,
    mounting: str = 'E',
    depth_mm: float | None = None,
    deflection_mm: float = 0.0,
    substructure_width_mm: float = 0.0,
    substructure_height_mm: float = 0.0,
    fixture_density_kg_m2: float = 20.0,
    support_width_mm: float = 0.0,
    support_height_mm: float = 0.0,
    support_centre_distance_m: float | None = None,
    relative_humidity_percent: ArrayLike | None = None,
) -> CeilingSpecimenCheck

Does the test arrangement meet the printed limits of clause 4?

Clause 4 of EN 16487, “Test arrangements”, holds both the specimen of 4.1 and the temperature and humidity of 4.2. The verdict judges every bound of it that a number of the arrangement as built can be held to:

a mounting fixture of at least 20 kg/m2 (4.1.1.1.6);
a substructure profile no wider than 30 mm and no higher than 50 mm (4.1.1.2.3.4);
a deflection of the specimen of no more than 5 mm (4.1.1.2.3.5);
support units no larger than 50 mm by 50 mm in cross-section, at centre distances of at least 1,2 m (4.1.1.2.3.6);
when it is given, a relative humidity of at least 50 % in every measurement (4.2.2, checked for each measurement by 4.2.3).

Leaving one of them raises a SuspendedCeilingWarning that names it, and makes satisfied false. A substructure and support units are what 4.1.1.2.3.4 and 4.1.1.2.3.6 allow rather than require, so their dimensions default to zero, which is none at all, and the centre distance is judged only when it is given. The cap of 4.2.1 on the air-absorption correction is judged where that correction is computed, by air_absorption_correction.

Two figures are reported and kept out of the verdict. The area error, because 4.1.1.1.1 asks for an area “as close to 10,80 m2 as possible”, which is a target and not a tolerance. And whether a type E depth is the 200 mm that 4.1.1.2.3.1 recommends and fixes for the data CE marking is compiled from: another depth is said in the warning and passes.

Three printed figures are targets to build to and are not judged at all: the 0,6 m by 0,6 m test object of 4.1.1.1.2 (TEST_OBJECT_SIZE_M), which “should” be that size and otherwise the closest in the product range; the 10 degree edge angle of 4.1.1.1.5 (MIN_ROOM_EDGE_ANGLE_DEG), which “should be aimed at”; and the substructure pitch of “approx. 0,6 m” of 4.1.1.2.3.4 (SUBSTRUCTURE_SPACING_M).

Parameters

Name	Description
`area_m2`	The specimen area as built, in square metres.
`mounting`	The mounting letter, `"E"` by default.
`depth_mm`	The overall depth of construction, in millimetres, required for a type E mounting.
`deflection_mm`	The largest deflection of the specimen, in millimetres.
`substructure_width_mm`	The substructure profile width, in millimetres.
`substructure_height_mm`	Its height, in millimetres.
`fixture_density_kg_m2`	The surface density of the mounting fixture, in kilograms per square metre.
`support_width_mm`	One side of the cross-section of the support units, in millimetres; zero when the substructure has none.
`support_height_mm`	The other side, in millimetres.
`support_centre_distance_m`	The centre distance between support units, in metres, or `None` when there are none or it was not recorded.
`relative_humidity_percent`	The relative humidity of the room in each measurement, in percent, one value per measurement, or `None` to leave 4.2.2 unjudged.

Returns: The verdict, as a CeilingSpecimenCheck.

Raises

Exception	When
ValueError	For a non-positive area or depth, a negative or non-finite deflection, substructure or support dimension or fixture density, a non-positive or non-finite support centre distance, a relative humidity that is empty, not one-dimensional, not finite or outside 0 % to 100 %, an unknown mounting letter, or a type E arrangement with no depth given.

EN16487_COVERAGE_FACTOR

Constant (float).

EN16487_COVERAGE_FACTOR = 2.8

MAX_DEFLECTION_MM

Constant (float).

MAX_DEFLECTION_MM = 5.0

MIN_FIXTURE_DENSITY_KG_M2

Constant (float).

MIN_FIXTURE_DENSITY_KG_M2 = 20.0

MIN_RELATIVE_HUMIDITY_PERCENT

Constant (float).

MIN_RELATIVE_HUMIDITY_PERCENT = 50.0

MIN_ROOM_EDGE_ANGLE_DEG

Constant (float).

MIN_ROOM_EDGE_ANGLE_DEG = 10.0

MIN_SUPPORT_SPACING_M

Constant (float).

MIN_SUPPORT_SPACING_M = 1.2

mounting_type

mounting_type(letter: str) -> str

What one mounting letter of EN ISO 354 Annex B means here.

Parameters

Name	Description
`letter`	`"A"`, `"B"`, `"E"` or `"J"`.

Returns: The description in the words of 4.1.1.2.

Raises

Exception	When
ValueError	For a letter this test code does not admit.

MOUNTING_TYPES

Constant (mapping).

MOUNTING_TYPES = {'A': 'attached directly against a hard surface, with no air space', 'B': 'glued to a hard surface with a 3 mm air space kept by corner shims', 'E': 'suspended from a hard surface with an air space behind it', 'J': 'a discrete absorber, freely suspended or standing'}

reproducibility_uncertainty

reproducibility_uncertainty(
    frequencies: ArrayLike | None = None,
) -> NDArray[np.float64]

Table 1, the reproducibility between European laboratories.

The figures are an expanded uncertainty: the round robin of Annex A gives a reproducibility standard deviation and ISO 5725-6 multiplies it by EN16487_COVERAGE_FACTOR. They hold for a plane absorber with the type E mounting and a 200 mm overall depth, and 6.2 says plainly that nothing has been investigated for any other absorber or mounting.

Parameters

Name	Description
`frequencies`	The nominal octave centres wanted, in hertz; omit for the six the table prints, in order.

Returns: The uncertainty of the absorption coefficient in each band.

Raises

Exception	When
ValueError	For a frequency Table 1 does not print.

SUBSTRUCTURE_LIMITS_MM

Constant (tuple).

SUBSTRUCTURE_LIMITS_MM = (30.0, 50.0)

SUBSTRUCTURE_SPACING_M

Constant (float).

SUBSTRUCTURE_SPACING_M = 0.6

SUPPORT_SECTION_MM

Constant (tuple).

SUPPORT_SECTION_MM = (50.0, 50.0)

SuspendedCeilingWarning

The test arrangement departs from a condition EN 16487 states.

Most often a limit of clause 4 it has left. The one exception is a type E depth other than 200 mm: the test code admits it, and the warning says only that the result is not the one CE marking data is compiled from.

TARGET_SPECIMEN_AREA_M2

Constant (float).

TARGET_SPECIMEN_AREA_M2 = 10.8

TEST_OBJECT_SIZE_M

Constant (tuple).

TEST_OBJECT_SIZE_M = (0.6, 0.6)

TYPE_E_DEPTH_MM

Constant (float).

TYPE_E_DEPTH_MM = 200.0

WEIGHTED_UNCERTAINTY

Constant (float).

WEIGHTED_UNCERTAINTY = 0.08

Created and maintained by José Manuel Requena Plens ORCID All projects