Predicting Sound Insulation (EN 12354)

Standards: EN 12354Key references: Hopkins 2007

A laboratory rating describes an element in isolation; a building also transmits sound along every flanking path. This page covers the EN 12354 prediction of in-situ performance between rooms from laboratory element data: the airborne model of EN 12354-1 with its junction vibration reduction indices, the impact model of EN 12354-2 and the prediction fiches of both. The third and fourth parts of the same family, which cross the building envelope instead of an internal partition, are in Façade Sound Insulation. The measured quantities the model is checked against live in Field Insulation Measurement (ISO 16283); the laboratory inputs come from Laboratory Insulation Measurement.

How do I predict sound insulation with EN 12354 in Python?

Build the three flanking paths of each junction with building.flanking_element(), then combine them with building.predicted_airborne_insulation(r_direct=57.0, flanking_paths=paths). For the EN 12354-1 Annex H.3 example below it returns r_prime_w = 52.2 dB, that is $R_{w}^{'}$ = 52 dB, and names the dominant path. Impact insulation goes through predicted_impact_insulation().

Predicting performance (EN 12354)

A laboratory rating describes an element in isolation, yet the sound a building actually transmits also travels around the partition (along the floor, up the façade, through the flanking walls), re-radiating into the receiving room. This flanking transmission is the whole difference between the laboratory $R$ and the field $R^{'}$ . EN 12354 predicts the in-situ apparent rating from the laboratory ratings of the elements plus the vibration transmission of their junctions.

The direct path Dd through the separating element and the three flanking paths Ff, Df and Fd across each junction between a flanking element and the separating element

Each junction between a flanking element and the separating element carries three paths, $F f$ (flanking→flanking), $D f$ (direct→flanking) and $F d$ (flanking→direct), alongside the single direct path $D d$ .

Download the animation (WebM)

The simplified single-number model combines them energetically (Formula 26):

R_{w}^{'} = - 10 lo g_{10} [1 0^{- R_{D d, w} /10} + \sum 1 0^{- R_{F f, w} /10} + \sum 1 0^{- R_{D f, w} /10} + \sum 1 0^{- R_{F d, w} /10}],

with the direct path $R_{D d, w} = R_{s, w} + Δ R_{D d, w}$ (Formula 27) and each flanking path (Formula 28a)

R_{ij, w} = \frac{R _{i, w} + R _{j, w}}{2} + Δ R_{ij, w} + K_{ij} + 10 lo g_{10} \frac{S _{s}}{l _{0} l _{f}},

where $l_{0} = 1$ m is the reference coupling length, $l_{f}$ the junction coupling length and $K_{ij}$ the junction’s vibration reduction index.

Reading $K_{ij}$

$K_{ij}$ is a property of the junction alone, and that is the whole point of it. It is the average of the two velocity level differences measured across the junction, corrected for the coupling length and for the equivalent absorption lengths of the two elements, so the same junction carries the same $K_{ij}$ whatever building it is built into — which is what lets a catalogue of junction types exist. Bigger is better: $K_{ij}$ enters Formula (28a) with a plus sign, so a high value is a junction that does not pass vibration on. The ranges are worth carrying in your head. A rigid cross junction of similar masses sits around 8–13 dB and a rigid T junction about 3 dB lower (Annex E.3.2/E.3.3 give $K_{13} = 8, 7 + 17, 1 M + 5, 7 M^{2}$ and $5, 7 + 14, 1 M + 5, 7 M^{2}$ ); the corner and thickness-change junctions of Annex E.3.6 fall to $15 M - 3$ dB (floored at $- 2$ dB) and $5 M^{2} - 5$ dB, so at the worked example’s mass ratio they return 0,1 dB and $- 4, 8$ dB — a junction that hides nothing; and a resilient interlayer or a lightweight double-leaf junction can exceed 20 dB (the same mass ratio through a flexible_t gives 20,9 dB). That upper range is what makes the internal wall of the worked example below almost invisible: it is the weakest element on the list at $R_{w}$ = 33 dB, yet the 33,5 dB tabulated for its $K_{F f}$ takes its Ff path out of the sum entirely. On this model a bad element behind a good junction beats a good element behind a bad one. For the simplified model the Annex E values are read once, at 500 Hz, and stand in for a quantity that is only approximately frequency-independent.

The mass argument is the place readers come unstuck. The Annex E fits are quadratic in $M = l g (m_{⊥, i}^{'} / m_{i}^{'})$ — the base-ten logarithm of the mass ratio, with $m_{i}^{'}$ the element carrying the path and $m_{⊥, i}^{'}$ the perpendicular element of the junction (Formula E.3). The library takes the mass ratio itself and forms $M$ internally, so mass_ratio=1.61 means the perpendicular element is 1,61 times as heavy per unit area. Any positive number is accepted, so passing an already-logged value returns a plausible but wrong answer: junction_vibration_reduction("rigid_cross", "through", 0.2068) returns $- 0, 3$ dB where the answer is 12,5 dB. And because $m_{i}^{'}$ is the element in the transmission path, the same junction has a different mass ratio for $K_{13}$ and for $K_{12}$ — the ratio is per path, not per junction.

The Annex E junction catalogue: rigid cross, rigid T, T with a flexible interlayer, corner, thickness change and a lightweight double-leaf wall meeting a homogeneous floor, each with its elements numbered, its path branches coloured, the coupling length marked and the mass ratio worked for one panel

Each drawing above maps onto one (junction_type, path) argument pair, and the path branch matters as much as the junction type: on the same rigid cross of the worked example, path='through' gives 12,5 dB and path='corner' 8,9 dB.

Per-path indices above, share of transmitted energy below. The direct path is the strongest single contributor at 33 %, yet two thirds of what arrives in the receiving room has gone around the wall — which is the 5 dB between $R_{s, w} = 57$ dB and $R_{w}^{'} = 52$ dB. The dashed line is the assembled $R_{w}^{'}$ , which necessarily sits below every individual path.

import numpy as np
from phonometry import building

# EN 12354-1 Annex H.3: a separating wall Rs,w = 57 dB, area Ss = 11.5 m², with
# four flanking elements. The simplified model reads each junction's Kij at
# 500 Hz from the mass ratio m'perp / m' (Annex E) — here the floor's rigid
# cross-junction (the mass ratio is itself rounded, hence 12.5 vs Annex 12.4):
print(round(building.junction_vibration_reduction("rigid_cross", "through", 1.61), 1))  # 12.5  KFf
print(round(building.junction_vibration_reduction("rigid_cross", "corner",  1.61), 1))  #  8.9  KFd = KDf

# Build each element's three flanking paths (Ff, Df, Fd) from the Annex H
# tabulated Kij, then combine the direct path Dd energetically (Formula 26).
elements = [   # (name, Rw, KFf, KFd = KDf, coupling length lf)
    ("floor",    49, 12.4,  8.9, 4.50),
    ("ceiling",  46, 14.4,  9.2, 4.50),
    ("facade",   42, 12.6,  6.7, 2.55),
    ("int-wall", 33, 33.5, 15.7, 2.55),
]
paths = []
for name, rw, k_ff, k_fd, lf in elements:
    paths += building.flanking_element(label=name, r_flanking=rw, r_separating=57,
                              k_ff=k_ff, k_fd=k_fd, k_df=k_fd,
                              separating_area=11.5, coupling_length=lf)

res = building.predicted_airborne_insulation(r_direct=57.0, flanking_paths=paths)
print(round(res.r_prime_w, 1))                          # 52.2  ->  R'w = 52 dB
print(res.dominant.label, round(res.dominant.fraction, 2))   # Dd 0.33 (direct dominates)

res.plot()   # per-path share of the transmitted energy, largest first (needs matplotlib)

Show the code for this figure

import matplotlib.pyplot as plt
from phonometry import building

# Build each element's three flanking paths (Ff, Df, Fd) from the Annex H
# tabulated Kij, then combine the direct path Dd energetically (Formula 26).
elements = [   # (name, Rw, KFf, KFd = KDf, coupling length lf)
    ("floor",    49, 12.4,  8.9, 4.50),
    ("ceiling",  46, 14.4,  9.2, 4.50),
    ("facade",   42, 12.6,  6.7, 2.55),
    ("int-wall", 33, 33.5, 15.7, 2.55),
]
paths = []
for name, rw, k_ff, k_fd, lf in elements:
    paths += building.flanking_element(label=name, r_flanking=rw, r_separating=57,
                              k_ff=k_ff, k_fd=k_fd, k_df=k_fd,
                              separating_area=11.5, coupling_length=lf)
res = building.predicted_airborne_insulation(r_direct=57.0, flanking_paths=paths)

# Per-path sound reduction index and each path's share of the transmitted
# energy for the Annex H.3 result computed above.
labels = [p.label for p in res.paths]
r_w = [p.r_w for p in res.paths]
frac = [100.0 * p.fraction for p in res.paths]

fig, (ax1, ax2) = plt.subplots(2, 1, figsize=(9, 6), sharex=True)
ax1.bar(labels, r_w, color="tab:blue")
ax1.axhline(res.r_prime_w, ls="--", color="k", label=f"R'w = {res.r_prime_w:.1f} dB")
ax1.set_ylabel("Path Rij,w [dB]"); ax1.legend()
ax2.bar(labels, frac, color="tab:orange")
ax2.set_ylabel("Energy share [%]"); ax2.set_xlabel("Transmission path")
for ax in (ax1, ax2):
    ax.tick_params(axis="x", rotation=45)
fig.suptitle("EN 12354-1 Annex H.3 — flanking transmission")
fig.tight_layout()
plt.show()

Every added flanking path strictly lowers $R_{w}^{'}$ below the direct $R_{D d, w} = 57$ ; res.paths exposes each path’s share of the transmitted energy so the dominant path is visible.

Read the split as a budget, because that is the practical yield of the whole model. The direct path is the largest single contributor here and it still carries only 33 % of the transmitted energy: two thirds of what arrives has gone around the wall. So perfecting the separating wall — making it infinitely good, not merely better — removes at most a third of the total, which is $- 10 l g (1 - 0.33) = 1.8$ dB. Specifying a heavier partition on this construction would be wasted money; the floor, the ceiling and the façade carry the rest, and a junction detail or a lining on them is what moves the answer. The rule generalises: the best achievable improvement from fixing one path is $- 10 l g (1 - its energy fraction)$ dB, so a path below about 10 % of the total is worth at most 0,5 dB and is not worth touching, while a path at 50 % is worth 3 dB and one at 80 % is worth 7 dB. Rank the paths, spend on the top of the list, and stop when the next one is under a decibel.

flanking_element is a convenience that builds one junction’s three paths at once; the single-path constructor behind it, flanking_path, builds one Ff, Df or Fd path at a time (Formula 28a). Clause 4.4.2 also enforces a floor $K_{ij} \geq K_{ij, m i n}$ from the junction geometry (Formula 29). Pass the flanking-element area to flanking_element(..., flanking_area=...) and the clamp is applied automatically per path; or compute the floor yourself with junction_min_vibration_reduction and pass it to flanking_path(..., kij_min=...), which raises a below-floor $K_{ij}$ to the minimum.

Why a floor at all? $K_{ij}$ is defined relative to the equivalent absorption lengths of the two elements, so on small elements the normalisation itself limits how much junction isolation may be claimed: energy arriving at a small, lightly damped element has nowhere to be dissipated except back across the junction it came through. The floor therefore rises as the elements shrink or the coupling length grows. On dwelling-scale elements it is normally negative and inactive; a prediction in which the clamp is active is a signal that an Annex E tabulated value is being applied outside the geometry it was fitted on.

from phonometry import building
# Kij,min = 10 lg[lf·l0·(1/Si + 1/Sj)]; large elements give a low (here negative)
# floor, so a realistic tabulated Kij is rarely clamped; but small, light
# elements can push it above the tabulated value (e.g. lf = 4 m, S = 1.5 m²
# gives 7.3 dB, over the 5 dB lightweight floor).
print(round(building.junction_min_vibration_reduction(coupling_length=4.5,
                                             s_i=11.5, s_j=11.5), 1))     # -1.1

Two linings on one path do not add

delta_r_ff, delta_r_fd, delta_r_df and flanking_path’s delta_r are each the combined improvement of one whole path, not one lining’s rating. A path usually has two ends, and both may be lined: a wall lining on the source side and a suspended ceiling on the receiving side both sit on the same $F f$ path. They do not add. ISO 12354-1:2017 Formula (22) for the direct path and Formula (23) for each flanking path both give

Δ R_{ij, w} = Δ R_{i, w} + \frac{Δ R _{j, w}}{2} or Δ R_{j, w} + \frac{Δ R _{i, w}}{2} dB,

with the rule that decides which of the two: half the value is taken for the lining with the lower value; however, if both linings have a negative value, half the value is taken for the lining with the higher value. So two linings of +12 dB and +6 dB give 12 + 3 = 15 dB, not 18; and two of $- 4$ dB and $- 9$ dB give $- 9 - 2 = - 11$ dB, because with both negative it is the less negative one that is halved. The sign rule inverts which lining is halved, and it is the part a careful reader still gets wrong.

The physics behind the halving is that two linings in series on the same vibrational path are not independent: the second one operates on a field the first has already reduced, so its full rating — measured on a bare element — is not available a second time. ISO 12354-2 Clause 4.3.3 carries the same rule where a floor covering and a receiving-side lining coexist. The direct path takes its own combined $Δ R_{D d, w}$ through delta_r_direct.

The impact counterpart (EN 12354-2, Formula 21) is a direct subtraction: $L_{n, w}^{'} = L_{n, w, e q} - Δ L_{w} + K$ , with the bare-floor equivalent level $L_{n, w, e q} = 164 - 35 lo g_{10} (m^{'} / m_{0}^{'})$ (Annex B), the covering improvement $Δ L_{w}$ (ISO 717-2) and the flanking correction $K$ from Table 1.

Check which edition your regulation cites. The model above is the EN 12354-2:2000 one, which condenses all flanking transmission into the single tabulated correction $K$ read from the separating and mean flanking masses. ISO 12354-2:2017 reorganised the same simplified model into explicit per-path formulae — $L_{n, d, w} = L_{n, e q, 0, w} - Δ L_{w} - Δ L_{d, w}$ (15) for the direct path and, for each flanking path, $L_{n, ij, w} = L_{n, e q, 0, w} - Δ L_{w} + (R_{i, w} - R_{j, w}) /2 - Δ R_{j, w} - K_{ij} - 10 lo g_{10} (S_{i} / l_{0} l_{ij})$ (16) — so the Table 1 correction is not in the current text at all, even though the underlying physics and the accuracy statement are unchanged. The 2017 edition also states a field of application the 2000 text left implicit (Clause 4.3.1): the simplified model is restricted to 100 Hz–3150 Hz, and for lightweight constructions to the measured normalised flanking impact level route $L_{n f, ij}$ of Formula (17). The frequency-band route of Detailed Sound Insulation Prediction is anchored on the 2017 editions throughout.

What the two mass inputs are, and where the closed form stops. Annex B’s $164 - 35 l g (m^{'} / m_{0}^{'})$ is not a theory: it is a regression fitted to measured homogeneous heavyweight floors between 100 and 600 kg/m², and equivalent_impact_level raises a UserWarning when it is called outside that band. It works inside it because a bare massive slab’s impact level is set by its mass and by the roughly constant loss factor of masonry construction. It fails outside it because a light or ribbed floor radiates through its own resonances rather than as a damped homogeneous plate — so the closed form is meaningless for a hollow-core, beam-and-block or joisted deck at any mass, and an extrapolation for a 900 kg/m² vault. The $m^{'}$ it wants is the mass of the bare structural floor, without covering and without ceiling; the covering’s effect is $Δ L_{w}$ and is subtracted separately.

The flanking mass is a different quantity again: the arithmetic mean over the homogeneous flanking elements of the receiving room that carry no additional layer. A lined or dry-lined flanking wall is left out of the mean, not averaged in at its bare mass. Table 1 itself applies to the rooms-one-above-the-other case of the Annex E.3 example, and it is a discrete nearest-neighbour lookup, not an interpolation: 145 kg/m² and 150 kg/m² both return $K$ = 2 dB, and masses outside 100–900 kg/m² (separating) or 100–500 kg/m² (flanking) clamp to the nearest edge rather than extrapolating. Taken together, a lightweight building is outside this whole simplified impact route and needs the measured normalised flanking impact level path the 2017 edition prescribes.

from phonometry import building

# EN 12354-2 Annex E.3: a 0.14 m concrete floor (m' = 322 kg/m²) with a floating
# floor (ΔLw = 33 dB), rooms one above the other, mean flanking mass 145 kg/m².
ln_eq = building.equivalent_impact_level(322.0)                   # 164 - 35 lg(m')
k = building.impact_flanking_correction(322.0, 145.0)             # Table 1 (sep 322, flk 145)
imp = building.predicted_impact_insulation(ln_w_eq=ln_eq, delta_l_w=33.0, k_correction=k)
print(round(ln_eq, 1), k, round(imp.l_prime_n_w, 1))     # 76.2 2 45.2  ->  L'n,w = 45 dB

# The lookup is discrete: the next tabulated flanking mass gives the same K.
print(building.impact_flanking_correction(322.0, 150.0))          # 2, unchanged

# Exact Formula (3): L'nT,w = L'n,w - 10 lg(0.032 V). Annex E.3's own rounding
# of the factor to 10 lg(V/30) sits 0.18 dB below; both give L'nT,w = 43 dB.
print(round(building.standardized_impact_level(imp.l_prime_n_w, 50.0), 1))   # 43.2  L'nT,w

imp.plot()   # the Formula (21) terms as bars: Ln,w,eq - dLw + K -> L'n,w (needs matplotlib)

The EN 12354-2 Annex E.3 impact prediction as its Formula 21 terms: the bare-floor equivalent level of 76.2 dB, the minus 33 dB floating-floor improvement, the plus 2 dB flanking correction, and the resulting predicted apparent impact level of 45.2 dB

The whole EN 12354-2 simplified model is one subtraction: the massive bare floor starts at $L_{n, w, e q} = 76.2$ dB, the floating floor buys back 33 dB, and the flanking correction returns 2 dB, landing at $L_{n, w}^{'} = 45$ dB.

Show the code for this figure

import matplotlib.pyplot as plt
import numpy as np
from phonometry import building

# EN 12354-2 Annex E.3: 0.14 m concrete floor (m' = 322 kg/m2), floating
# floor delta-Lw = 33 dB, mean flanking mass 145 kg/m2.
ln_eq = building.equivalent_impact_level(322.0)
k = building.impact_flanking_correction(322.0, 145.0)
imp = building.predicted_impact_insulation(ln_w_eq=ln_eq, delta_l_w=33.0,
                                           k_correction=k)

# One line — the Formula (21) terms as bars:
imp.plot()
plt.show()

# By hand, from the result's fields:
labels = ["Ln,w,eq", "-dLw", "+K", "L'n,w"]
values = [imp.ln_w_eq, -imp.delta_l_w, imp.k_correction, imp.l_prime_n_w]
fig, ax = plt.subplots()
ax.bar(np.arange(4), values)
ax.axhline(0.0, color="k", lw=0.8)
ax.set_xticks(np.arange(4), labels)
ax.set_ylabel("Level / correction [dB]")
ax.set_title(f"L'n,w = {imp.l_prime_n_w:.1f} dB (EN 12354-2 Annex E.3)")
plt.show()

The airborne counterpart of that closure is Formula (5b), $D_{n T} = R^{'} + 10 lo g_{10} (0.32 V / S_{s})$ , exposed as standardized_level_difference; it closes the Annex H.3 example (standardized_level_difference(52.2, 50.0, 11.5) gives 53.6 dB, the printed $V / (3 S)$ chain 53.8 dB, both rounding to $D_{n T, w} = 54$ dB).

The three insulation guides close a loop: the laboratory measures $R$ and $K_{ij}$ element by element and junction by junction, this model assembles them into a predicted $R_{w}^{'}$ , and the field measurement checks the built result. When the measured value lands well below the prediction, look for a construction defect on the dominant path the model reports: a rigid bridge across a resilient junction, a missing lining, a leak around the separating element.

`junction_vibration_reduction()` / `flanking_element()` parameters

Parameter	Type	Units	Range / default	Notes
`junction_type`	str	—	`'rigid_cross'` / `'rigid_t'` / `'flexible_t'` / `'lightweight_facade'` / `'lightweight_double_homogeneous'` / `'lightweight_double_coupled'` / `'corner'` / `'thickness_change'`	Junction geometry (Annex E.3-E.9)
`path`	str	—	`'through'` ( $K_{13}$ ) / `'corner'` ( $K_{12} = K_{23}$ ) / `'double_leaf'` ( $K_{24}$ )	Path branch
`mass_ratio`	float	—	> 0	$m_{⊥, i}^{'} / m_{i}^{'}$ (Formula E.2)
`frequency`	float	Hz	default `500`	`flexible_t` and the E.7/E.8 double-leaf junctions are frequency-dependent
`r_flanking` / `r_separating`	float	dB	—	Weighted indices of the flanking / separating element
`k_ff` / `k_fd` / `k_df`	float	dB	—	Junction $K_{ij}$ for the three paths
`separating_area`	float	m²	> 0	Separating-element area $S_{s}$
`coupling_length`	float	m	> 0	Junction coupling length $l_{f}$
`delta_r_ff` / `delta_r_fd` / `delta_r_df`	float	dB	default `0`	Combined lining improvement of the whole path, both ends together (Formula 23)
`flanking_area`	float	m²	default `None`	Flanking-element area $S_{F}$ ; enables the automatic $K_{ij, m i n}$ clamp (Clause 4.4.2 / Formula 29)

`flanking_path()` parameters

Parameter	Type	Units	Range / default	Notes
`label`	str	—	—	Display name of the path
`kind`	str	—	`'Ff'` / `'Df'` / `'Fd'`	Which flanking branch the path is
`r_source` / `r_receive`	float	dB	—	Weighted indices of the source-side / receive-side elements
`k_ij`	float	dB	—	Junction vibration-reduction index for this path
`separating_area`	float	m²	> 0	Separating-element area $S_{s}$
`coupling_length`	float	m	> 0	Junction coupling length $l_{f}$
`delta_r`	float	dB	default `0`	Combined lining improvement of this path, both ends together (Formula 23)
`kij_min`	float	dB	default `None`	When given, `k_ij` is floored at this Formula (29) minimum

predicted_airborne_insulation() returns an AirbornePredictionResult (r_prime_w, r_direct_w, paths of PathContribution, dominant); predicted_impact_insulation() an ImpactPredictionResult (l_prime_n_w, ln_w_eq, delta_l_w, k_correction). The simplified model carries a reported standard deviation of about 2 dB (Clause 5).

When the simplified model applies

Clause 4.4.4 of ISO 12354-1:2017 sets three conditions, and none of them is about arithmetic.

Similar frequency dependence. The model assumes elements whose sound reduction index has a broadly similar shape against frequency, since it works on single numbers and a single number cannot carry two different shapes. A masonry wall flanked by masonry is the model’s home ground; a lightweight double-leaf partition beside a concrete floor is explicitly named as the case where the accuracy may be less.
Dwelling-scale geometry. It applies mainly to dwellings whose element dimensions are similar to those of a test facility. Move far from that — a hall, a plant room, a very long junction — and the deviation grows.
Adjacent rooms only. Clause 4.2.4 restricts the whole family to transmission between rooms that share the separating element, and secondary paths crossing more than one junction are neglected. Where the source is several junctions away, the EN 12354-5 route chains the junction indices instead.

And the ~2 dB standard deviation is not a tolerance on your answer. Clause 5 prints it assuming good workmanship and high measurement accuracy, and adds the advice that makes it usable: vary the input data, especially in complicated situations and with atypical elements, and read the spread in the result; Annex K systematises that into an uncertainty derived from the accuracy of every acoustic input.

The junction data deserve their own warning, because their spread is larger than the model’s. Annex E.3.1 states four things the page’s lookup does not show. Data exist only for junctions where the elements on either side in the same plane have the same mass. The measured points scatter by a typical ±3 dB about the printed lines, and “in some cases the deviation can be much larger due to variations in junction details and in workmanship” — which is larger than the ~2 dB of the whole model, so on most real predictions the junction input, not the summation, dominates the error. The $K_{ij}$ values were deduced so that the estimated junction velocity level difference is right on average, which puts them generally 5 dB below the direction-averaged junction velocity level difference, so a measured $D_{v, ij}$ cannot be substituted for a $K_{ij}$ without that step. And the frequency independence holds “at least in the frequency range from 125 Hz to 2 000 Hz”; outside it the frequency effect can be larger. The way out is measured data: ISO 10848-4 for heavy junctions — which Annex E.3.1 itself recommends gathering at national level — and the flanking laboratory where the junction is lightweight, non-homogeneous or simply not in the catalogue.

EN 12354 prediction report (`.report()`)

Both prediction results write a one-page prediction report through a report(path) method. Unlike the measurement fiches, the reported result is an estimate of the in-situ performance from the elements’ laboratory data plus the flanking transmission across the junctions; the sheet states this explicitly and is labelled a prediction, never a measurement. AirbornePredictionResult.report() renders the predicted apparent sound reduction index fiche (the transmission-path table beside the per-path share-of-energy plot, the boxed $R_{w}^{'}$ ); ImpactPredictionResult.report() renders the predicted apparent impact-level fiche (the Formula (21) term table beside the term plot, the boxed $L_{n, w}^{'}$ ). Each names EN/ISO 12354-1/-2 and the ISO 717 rating part in its basis line, prints the model’s ~2 dB standard deviation and, when a requirement is supplied, adds a PASS/FAIL verdict (airborne passes at or above it, impact at or below it).

verbose=True annexes each transmission path’s share of the transmitted energy to the airborne table. Metadata, language="es" and the phonometry[report] extra behave exactly as in the measurement fiches; the applicable ReportMetadata fields are the separating element (specimen), the separating-element or floor area (area), the room geometry (source_volume, receiving_volume), the bare floor’s mass (mass_per_area, impact), the manufacturer (manufacturer), the test room or facility (test_room), the calculator/laboratory identity (client, laboratory, operator, report_id, test_date) and a free-text summary of the flanking construction and model assumptions (notes).

from phonometry import building, ReportMetadata

# Airborne prediction (EN 12354-1 Annex H.3): a separating wall Rs,w = 57 dB
# flanked by four elements -> R'w = 52 dB.
paths = []
for label, rw, kff, kfd, lf in [
    ("floor", 49.0, 12.4, 8.9, 4.5), ("ceiling", 46.0, 14.4, 9.2, 4.5),
    ("facade", 42.0, 12.6, 6.7, 2.55), ("intwall", 33.0, 33.5, 15.7, 2.55),
]:
    ff, df, fd = building.flanking_element(
        label=label, r_flanking=rw, r_separating=57.0,
        k_ff=kff, k_fd=kfd, k_df=kfd, separating_area=11.5, coupling_length=lf)
    paths += [ff, df, fd]
air = building.predicted_airborne_insulation(r_direct=57.0, flanking_paths=paths)
air.report("Rpw_prediction.pdf", metadata=ReportMetadata(
    specimen="Separating wall, Rs,w = 57 dB", area=11.5,
    source_volume=53.0, receiving_volume=50.0, requirement=50.0,
    notes="Flanking: floor/ceiling/facade/internal wall."))   # R'w = 52 dB
air.report("Rpw_prediction_paths.pdf", verbose=True)           # + energy share

# Impact prediction (EN 12354-2 Annex E.3): a concrete floor (m' = 322 kg/m²)
# with a floating floor (ΔLw = 33 dB) -> L'n,w = 45 dB.
ln_eq = building.equivalent_impact_level(322.0)
k = building.impact_flanking_correction(322.0, 145.0)
imp = building.predicted_impact_insulation(ln_w_eq=ln_eq, delta_l_w=33.0, k_correction=k)
imp.report("Lnw_prediction.pdf",
           metadata=ReportMetadata(mass_per_area=322.0, requirement=53.0))  # L'n,w = 45 dB

Both example fiches are regenerated with make reports and kept rendered in the repository; click either preview to open the PDF.

Predicted airborne EN 12354-1 example report (PDF) — Predicted airborne fiche (AirbornePredictionResult.report), R'w.

Predicted impact EN 12354-2 example report (PDF) — Predicted impact fiche (ImpactPredictionResult.report), L'n,w.

Across the envelope: Parts 3 and 4

The two remaining parts of EN 12354 predict the same way but across the building envelope rather than between two rooms: EN 12354-3 the airborne insulation against outdoor sound, EN 12354-4 the sound power an indoor source radiates outwards. Both are built on the same area-weighted summation of element transmission factors used above, and both are covered, beside the ISO 16283-3 measurement they are compared against, in Façade Sound Insulation.

What this guide covers

Covered
The simplified single-number models of EN 12354-1:2000 (Clause 4.4) and EN 12354-2:2000 (Clause 4.3). Airborne: the Formula (26) energetic sum of the direct and flanking paths through building.flanking_path, building.flanking_element and building.predicted_airborne_insulation, with the Annex E vibration reduction indices $K_{ij}$ (rigid cross and T junctions, flexible interlayers, lightweight façades and double-leaf walls, corners and thickness changes) and the Clause 4.4.2 floor $K_{ij, m i n}$ via building.junction_vibration_reduction and building.junction_min_vibration_reduction. Impact: the Formula (21) subtraction $L_{n, w}^{'} = L_{n, w, e q} - Δ L_{w} + K$ through building.equivalent_impact_level, building.impact_flanking_correction, building.predicted_impact_insulation and building.standardized_impact_level. Both results write a prediction fiche with .report().
Not covered
The detailed per-band models of both parts are the subject of Detailed Per-Band Prediction (ISO 12354): the same standard run band by band, with the laboratory element and junction data converted to their in-situ values before the paths are formed. Use the simplified model here when only the weighted element ratings are known and the question is whether the room passes; use the detailed one when the element spectra exist and the question is which path sets which band. The element inputs themselves ( $R_{w}$ , $Δ R_{w}$ , $Δ L_{w}$ , mass per unit area) are taken as given, from laboratory data or from the mass-law estimates of Predicting Panel Sound Insulation. The rest of the family is covered by its own guides: EN 12354-3 and EN 12354-4 across the building envelope in Façade Sound Insulation, EN 12354-5’s service equipment in Installed structure-borne sound and EN 12354-6’s absorption model in Sound absorption in enclosed spaces.

References

European Committee for Standardization. (2000). Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 1: Airborne sound insulation between rooms (EN 12354-1:2000). The simplified airborne flanking-transmission prediction (Annex E junctions, worked example H.3). The linked catalogue record is the BSI Knowledge page for BS EN 12354-1:2000.
European Committee for Standardization. (2000). Building acoustics — Estimation of acoustic performance of buildings from the performance of elements — Part 2: Impact sound insulation between rooms (EN 12354-2:2000). The simplified impact flanking-transmission prediction (worked example E.3). The linked catalogue record is the BSI Knowledge page for BS EN 12354-2:2000.
Hopkins, C. (2007). Sound insulation. Butterworth-Heinemann. https://doi.org/10.4324/9780080550473The full treatment of flanking transmission and the EN 12354 prediction framework, from the vibration reduction index to its statistical basis. ISBN 978-0-7506-6526-1.

Created and maintained by José Manuel Requena Plens ORCID All projects