Source: https://docs.jmrp.io/phonometry/buildings/insulation/insulation-ratings/ # Insulation Ratings (ISO 717) Every sound-insulation quantity in this documentation ends its journey the same way: a band spectrum walks in, a single number walks out. Whether the spectrum is a laboratory $R$, a field $R'$ or $D_{\mathrm{n}T}$, a façade $D_{2\mathrm{m,n}T}$, an impact $L_\mathrm{n}$ or $L'_{\mathrm{n}T}$, or a flanking $D_\mathrm{n,f}$, what regulations quote is the weighted single number of ISO 717, and two reference-curve engines produce all of them: **ISO 717-1** for airborne quantities, where an unfavourable deviation is a band falling *below* the reference, and **ISO 717-2** for impact quantities, with the sign flipped because a higher impact level is worse. This guide covers the engines themselves: the shifting rule, the spectrum adaptation terms $C$, $C_\mathrm{tr}$ and $C_\mathrm{I}$, the enlarged-range and one-decimal variants, and the ISO 717 fiche. The measurements that produce the spectra live in the [field](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-field/), [laboratory](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-lab/), [intensity](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-intensity/), [survey](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-survey/) and [flanking](https://docs.jmrp.io/phonometry/buildings/insulation/flanking-lab/) guides; the prediction that consumes the ratings is [EN 12354](https://docs.jmrp.io/phonometry/buildings/design/insulation-prediction/). Calculation chain of the ISO 717 single-number ratings. Across the top, a strip of one-third-octave bands from 50 Hz to 5000 Hz: the 16 bands from 100 Hz to 3150 Hz drawn solid with 500 Hz picked out, the five octave bands from 125 Hz to 2000 Hz bracketed under them, and the bands at 50, 63, 80, 4000 and 5000 Hz dashed as an enlarged range that only the adaptation terms read, the 4000 and 5000 Hz bands in ISO 717-1 alone. A box states the rule both parts share: shift the Table 3 curve towards the measurement in 1 dB steps until the sum of unfavourable deviations is as large as possible but not more than 32.0 dB over 16 bands or 10.0 dB over 5, in 0.1 dB steps for the expression of uncertainty, and read the shifted curve at 500 Hz. Below it, two small charts side by side. On the left, ISO 717-1 for airborne sound: the reference curve moved 22 dB down onto a measured sound reduction index, with bars where the measurement falls below it that add up to 31.8 dB, giving Rw = 52 − 22 = 30 dB; C = 28 − 30 = −2 dB from spectrum No. 1, pink noise, and Ctr = 27 − 30 = −3 dB from spectrum No. 2, urban traffic, both over all 16 bands, stated as Rw(C;Ctr) = 30 (−2; −3) dB. On the right, ISO 717-2 for impact sound: the reference curve moved 19 dB up onto a measured normalized impact level, with bars where the measurement rises above it that add up to 28.0 dB, giving Ln,w = 60 + 19 = 79 dB, with 5 dB taken off when the bands are octaves, and CI from the unweighted energy sum of the first 15 bands, without 3150 Hz. Each side lists its enlarged-range terms, and a box at the foot carries Cj = XAj − Xw and CI = Ln,sum − 15 − Ln,w *One rule, two engines. Both parts shift their own Table 3 curve the same way, and the shift differs between them only in the side of the curve a deviation counts on: below it for airborne insulation, where the curve comes to rest 22 dB down with 31.8 dB of deviations and reads 30 dB at 500 Hz, and above it for impact sound, where it comes to rest 19 dB up with 28.0 dB and reads 79 dB. Where the bands are octaves, ISO 717-2 takes a further 5 dB off that reading and ISO 717-1 does not. The adaptation terms then go back to the measured bands, all 16 of them for $C$ and $C_\mathrm{tr}$ and only the first 15 for $C_\mathrm{I}$.* ## Airborne ratings (ISO 717-1) The band spectrum is collapsed to one number by the **reference-curve method** of ISO 717-1: a fixed reference curve is shifted in 1 dB steps toward the measured curve until the sum of *unfavourable* deviations (where the measurement falls below the reference) is as large as possible but not more than 32.0 dB (16 one-third-octave bands) or 10.0 dB (5 octave bands). The rating ($R_\mathrm{w}$, $R'_\mathrm{w}$, $D_{\mathrm{n}T,\mathrm{w}}$ …) is the shifted reference read at 500 Hz. The **spectrum adaptation terms** $C$ (pink noise) and $C_\mathrm{tr}$ (urban traffic) add the low-frequency penalty of a real source. The two terms re-rate the same measured curve against the two source spectra of ISO 717-1 Annex A: $C$ against A-weighted pink noise, representative of living activities (speech, music, radio, television), and $C_\mathrm{tr}$ against A-weighted urban road traffic, whose energy sits at low frequency. They are defined so that the rating plus the term ($R_\mathrm{w} + C$ for a laboratory index, $R'_\mathrm{w} + C$ or $D_{\mathrm{n}T,\mathrm{w}} + C$ for the quantities of the [field guide](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-field/), and likewise with $C_\mathrm{tr}$) is the A-weighted level difference achieved against that source. Reading them: * $C$ stays small for most constructions (0 to −2 dB is typical): the pink spectrum is close to the weighting already implicit in the reference curve. * $C_\mathrm{tr}$ punishes weak low-frequency insulation. A lightweight double leaf with its mass-air-mass resonance near 100 Hz can carry a $C_\mathrm{tr}$ of −5 to −10 dB, while a heavy monolithic wall with the same $R_\mathrm{w}$ loses far less: two constructions with equal ratings can differ audibly against traffic. * Design with the descriptor that matches the noise, carried by the field quantity the requirement rates: $R'_\mathrm{w} + C_\mathrm{tr}$ for a façade on a busy road, $D_{\mathrm{n}T,\mathrm{w}} + C$ (or the plain rating, where the regulation says so) between dwellings, the two example requirements of ISO 717-1, 5.3. Measured one-third-octave sound reduction index with the shifted ISO 717-1 reference curve and the resulting weighted rating at 500 Hz ```python from phonometry import building # Single-number rating from a measured 16-band R spectrum (ISO 717-1 Annex C) R = [20.4, 16.3, 17.7, 22.6, 22.4, 22.7, 24.8, 26.6, 28.0, 30.5, 31.8, 32.5, 33.4, 33.0, 31.0, 25.5] w = building.weighted_rating(R) print(w.rating, w.c, w.ctr) # 30 -2 -3 -> Rw(C;Ctr) = 30(-2;-3) w.plot() # measured R' vs shifted ISO 717-1 reference, deviations shaded (needs matplotlib) ```
Show the code for this figure ```python import matplotlib.pyplot as plt from phonometry import building # Single-number rating from a measured 16-band R spectrum (ISO 717-1 Annex C) R = [20.4, 16.3, 17.7, 22.6, 22.4, 22.7, 24.8, 26.6, 28.0, 30.5, 31.8, 32.5, 33.4, 33.0, 31.0, 25.5] w = building.weighted_rating(R) # One line — measured curve vs the shifted ISO 717-1 reference, deviations shaded: w.plot() plt.show() # By hand, from the band curve the result now carries: fig, ax = plt.subplots() ax.semilogx(w.band_centers, w.measured, "o-", label="Measured R'") ax.semilogx(w.band_centers, w.shifted_reference, "s--", label="Shifted reference") ax.fill_between(w.band_centers, w.measured, w.shifted_reference, where=w.measured < w.shifted_reference, interpolate=True, alpha=0.3, label="Unfavourable deviations") ax.set_xlabel("Frequency [Hz]") ax.set_ylabel("Sound reduction index [dB]") ax.set_title(f"Rw = {w.rating} dB (C={w.c:+d}; Ctr={w.ctr:+d})") ax.legend() plt.show() ```
### `weighted_rating()` parameters | Parameter | Type | Units | Range / default | Notes | | :--- | :--- | :--- | :--- | :--- | | `values_by_band` | 1D array | dB | 16 (thirds) or 5 (octaves) | Measured $R$, $R'$, $D_{\mathrm{n}T}$ … per band | | `bands` | str or `None` | — | `'third-octave'` / `'octave'` / `None` | `None` infers from the count | `weighted_rating()` returns a `WeightedRatingResult` (`rating`, `c`, `ctr`, `unfavourable_sum`, all integers except the sum). ## Impact ratings (ISO 717-2) The single-number rating (ISO 717-2) shifts the same style of reference curve, but an **unfavourable deviation now occurs where the measurement *exceeds* the reference** (impact noise is worse when higher), the sign opposite to ISO 717-1. The rating ($L_\mathrm{n,w}$, $L'_\mathrm{n,w}$, $L'_{\mathrm{n}T,\mathrm{w}}$) is the shifted reference read at 500 Hz; for octave bands it is then reduced by 5 dB. The spectrum adaptation term $C_\mathrm{I} = L_\mathrm{n,sum} - 15 - L_\mathrm{n,w}$ uses the energetic sum over 100–2500 Hz (the first 15 thirds, excluding 3150 Hz) or 125–2000 Hz (octaves). For measurements extended down to 50 Hz, `weighted_impact_rating_extended` additionally returns the enlarged-range term $C_{\mathrm{I},50\text{–}2500}$ (A.2.1 NOTE), and with `one_decimal=True` the 0.1 dB-step rating used in uncertainty statements (it reproduces the printed $L_\mathrm{n,r,0,w} = 77.6$ dB and $C_\mathrm{I,r,0} = -10.3$ dB of A.2.2). Measured one-third-octave normalized impact sound pressure level with the shifted ISO 717-2 reference curve and the resulting weighted rating read at 500 Hz ```python import numpy as np from phonometry import building # ISO 717-2 Annex C worked example: the bare heavy floor of Table C.1, # laboratory Ln in one-third octaves. CI is read over the 100-2500 Hz sum # that A.2.1 asks for, not over the sixteen bands the 2020 print of that # cell sums. l_n = np.array([62.1, 63.2, 63.5, 66.2, 68.5, 70.0, 71.7, 73.1, 73.8, 73.5, 73.8, 73.3, 73.1, 73.0, 72.4, 71.2]) # Weighted impact rating + spectrum adaptation term CI (ISO 717-2) res_imp = building.weighted_impact_rating(l_n) print(res_imp.rating, res_imp.ci, res_imp.unfavourable_sum) # 79 -11 28.0 -> Ln,w(CI)=79(-11) # Octave-band data carry the extra -5 dB reduction (Clause 4.3.2) octave = np.array([65.3, 64.5, 58.0, 55.8, 43.0]) print(building.weighted_impact_rating(octave).rating) # 54 res_imp.plot() # measured Ln vs shifted ISO 717-2 reference, measured-above shaded (needs matplotlib) ```
Show the code for this figure ```python import matplotlib.pyplot as plt import numpy as np from phonometry import building # 16 one-third-octave impact levels Ln, dB (ISO 717-2 Annex C worked # example, the bare heavy floor of Table C.1; the CI in the title is read # over the 100-2500 Hz sum that A.2.1 asks for). l_n = np.array([62.1, 63.2, 63.5, 66.2, 68.5, 70.0, 71.7, 73.1, 73.8, 73.5, 73.8, 73.3, 73.1, 73.0, 72.4, 71.2]) # Weighted impact rating + spectrum adaptation term CI (ISO 717-2) res_imp = building.weighted_impact_rating(l_n) # One line — measured Ln vs the shifted ISO 717-2 reference (measured-above shaded): res_imp.plot() plt.show() # By hand, from the band curve the result now carries (note the opposite sign: # an unfavourable deviation is where the MEASURED level exceeds the reference). # Here the input was Ln, so the rated quantity is Ln,w: fig, ax = plt.subplots() ax.semilogx(res_imp.band_centers, res_imp.measured, "o-", label="Measured Ln") ax.semilogx(res_imp.band_centers, res_imp.shifted_reference, "s--", label="Shifted reference") ax.fill_between(res_imp.band_centers, res_imp.shifted_reference, res_imp.measured, where=res_imp.measured > res_imp.shifted_reference, interpolate=True, alpha=0.3, label="Unfavourable deviations") ax.set_xlabel("Frequency [Hz]") ax.set_ylabel("Impact sound pressure level [dB]") ax.set_title(rf"$L_\mathrm{{n,w}}$ = {res_imp.rating} dB ($C_\mathrm{{I}}$ = {res_imp.ci:+d} dB)") ax.legend() plt.show() ```
Feeding this spectrum into `weighted_impact_rating` reproduces the ISO 717-2 Annex C rating (thirds $L_\mathrm{n,w} = 79$; octave 54, $C_\mathrm{I} = 0$) and, reading $C_\mathrm{I}$ over the 100–2500 Hz sum that A.2.1 specifies, $C_\mathrm{I} = -11$ for the thirds. The 2020 print of Table C.1 sums all sixteen bands in that cell and gives $-10$ instead; the registry entry is in [Errata](https://docs.jmrp.io/phonometry/reference/errata/). ### `weighted_impact_rating()` parameters | Parameter | Type | Units | Range / default | Notes | | :--- | :--- | :--- | :--- | :--- | | `values_by_band` | 1D array | dB | 16 (thirds) or 5 (octaves) | Measured $L_\mathrm{n}$, $L'_\mathrm{n}$ or $L'_{\mathrm{n}T}$ per band | | `bands` | str or `None` | — | `'third-octave'` / `'octave'` / `None` | `None` infers from the count | `weighted_impact_rating()` returns an `ImpactRatingResult` (`rating`, `ci` integers, `unfavourable_sum` in dB). ## Enlarged frequency ranges and one-decimal ratings When the measurement covers more than the core 100–3150 Hz bands, ISO 717-1 Annex B defines additional adaptation terms with the range as a subscript ($C_{50\text{–}3150}$, $C_{50\text{–}5000}$, $C_{100\text{–}5000}$ and the $C_\mathrm{tr}$ counterparts), computed with the Table B.1 spectra over the enlarged range. `weighted_rating_extended` takes the band values *with their centre frequencies* and returns the core rating plus every extended term the input covers (the impact counterpart `weighted_impact_rating_extended` adds $C_{\mathrm{I},50\text{–}2500}$). With `one_decimal=True` the reference curve shifts in 0.1 dB steps and all reductions keep one decimal: the variant ISO 717 prescribes "for the expression of uncertainty" and ISO 12999-1 Annex B requires when stating the uncertainty of a single-number value. Where those extra bands come from matters as much as what the term does with them. In a room whose volume, to the nearest cubic metre, is under 25 m³, ISO 16283 does not let the 50 Hz, 63 Hz and 80 Hz bands be measured with the default procedure alone: the corner procedure is mandatory there, and it can move those three bands by several decibels, which can move $C_{50\text{–}3150}$ by a whole one. So a requirement written as $D_{\mathrm{n}T,\mathrm{w}} + C_{50\text{–}3150}$ is judged on the corner procedure whether the report mentions it or not. See [Small Rooms: the ISO 16283 Low-Frequency Procedure](https://docs.jmrp.io/phonometry/buildings/insulation/low-frequency-procedure/). ```python from phonometry import building # Single-number rating from a measured 16-band R spectrum (ISO 717-1 Annex C) R = [20.4, 16.3, 17.7, 22.6, 22.4, 22.7, 24.8, 26.6, 28.0, 30.5, 31.8, 32.5, 33.4, 33.0, 31.0, 25.5] freqs = [50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3150, 4000, 5000] r_ext = [18.7, 19.2, 20.0, *R, 26.8, 29.2] # ISO 717-1 Annex C, Table C.2 ext = building.weighted_rating_extended(r_ext, freqs) print(ext.rating, ext.c, ext.ctr, ext.c_50_5000, ext.ctr_50_5000) # 30 -2 -3 -2 -4 -> Rw(C;Ctr;C50-5000;Ctr,50-5000) = 30(-2;-3;-2;-4) one_dp = building.weighted_rating_extended(r_ext, freqs, one_decimal=True) print(one_dp.rating) # 30.0, the 0.1 dB-step rating for uncertainty statements ext.plot() # enlarged-range curve vs the shifted core reference, Annex B terms in the title (needs matplotlib) ``` Measured sound reduction index over the enlarged 50 Hz to 5 kHz range with the shifted ISO 717-1 reference curve on the 16 core bands, the unfavourable deviations shaded and the enlarged-range bands marked at both ends *The rating itself is still evaluated on the 16 core bands (100–3150 Hz); the enlarged bands only enter the Annex B adaptation terms, so the shifted reference curve stops at the core-range edges while the measured curve continues into the shaded enlarged range.*
Show the code for this figure ```python import matplotlib.pyplot as plt from phonometry import building # Single-number rating from a measured 16-band R spectrum (ISO 717-1 Annex C) R = [20.4, 16.3, 17.7, 22.6, 22.4, 22.7, 24.8, 26.6, 28.0, 30.5, 31.8, 32.5, 33.4, 33.0, 31.0, 25.5] freqs = [50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3150, 4000, 5000] r_ext = [18.7, 19.2, 20.0, *R, 26.8, 29.2] # ISO 717-1 Annex C, Table C.2 ext = building.weighted_rating_extended(r_ext, freqs) # One line — the enlarged-range curve vs the shifted core reference: ext.plot() plt.show() # By hand, from the band curves the result carries (the full enlarged-range # curve on ext, the core-band reference on ext.core): fig, ax = plt.subplots() ax.semilogx(ext.band_centers, ext.measured, "o-", label="Measured R") ax.semilogx(ext.core.band_centers, ext.core.shifted_reference, "s--", label="Shifted reference (core bands)") ax.fill_between(ext.core.band_centers, ext.core.measured, ext.core.shifted_reference, where=ext.core.measured < ext.core.shifted_reference, interpolate=True, alpha=0.3, label="Unfavourable deviations") ax.set_xlabel("Frequency [Hz]") ax.set_ylabel("Sound reduction index [dB]") ax.set_title(f"Rw = {ext.rating} dB (C50-5000={ext.c_50_5000:+g}; " f"Ctr,50-5000={ext.ctr_50_5000:+g})") ax.legend() plt.show() ```
## ISO 717 report (`.report()`) Both rating results render a one-page PDF fiche laid out like an accredited-laboratory test report through a `report(path)` method: a standard-basis line (measurement standard plus the ISO 717 rating part), an optional metadata header block, the one-third-octave table beside the measured-versus-shifted-reference plot (the result's own `.plot()`), the boxed single-number result, an optional verdict row and a footer with the fixed disclaimer. `WeightedRatingResult.report()` labels the airborne ISO 717-1 fiche ($R_\mathrm{w}\ (C\ ;\ C_\mathrm{tr})$, deviations where the reference is above the measurement); `ImpactRatingResult.report()` labels the impact ISO 717-2 fiche ($L_\mathrm{n,w}(C_\mathrm{I})$, deviations the opposite way). `SoundReductionResult.report()` is a convenience that rates the predicted $R(f)$ and writes its fiche in one call. The report metadata is supplied as a `ReportMetadata` frozen dataclass (every field optional; only the supplied fields are rendered, and the numeric fields must satisfy their field-specific physical ranges, detailed in the table below). Passing `metadata=None` produces a lightweight prediction fiche (body, result and disclaimer only). When `metadata.requirement` is set, a verdict row is added: an airborne rating passes when it is at or above the requirement, an impact rating when it is at or below it (a lower impact level is better). Setting `verbose=True` swaps the two-column `f | value` table for the ISO 717 Annex C columns (frequency, measured value, shifted reference, unfavourable deviation). Rendering needs reportlab, kept out of the runtime dependencies as the optional `phonometry[report]` extra (`pip install phonometry[report]`); a missing reportlab raises a clear `ImportError` with the install command, and the plot still needs matplotlib (`phonometry[plot]`). Only `engine="reportlab"` is supported; any other engine raises `ValueError`. The fiche renders in English by default; pass `language="es"` for a Spanish fiche (translated fixed strings and a comma decimal separator), e.g. `building.weighted_rating(R).report("Rw_fiche_es.pdf", language="es")`. ```python from phonometry import building, ReportMetadata # Airborne rating from a measured 16-band R spectrum (ISO 717-1) R = [20.4, 16.3, 17.7, 22.6, 22.4, 22.7, 24.8, 26.6, 28.0, 30.5, 31.8, 32.5, 33.4, 33.0, 31.0, 25.5] metadata = ReportMetadata( specimen="200 mm reinforced-concrete wall", client="Acoustic Test Client Ltd.", area=10.0, mass_per_area=460.0, source_volume=53.0, receiving_volume=51.0, temperature_c=21.5, relative_humidity_percent=45.0, static_pressure_kpa=101.3, test_room="Transmission suite T1", measurement_standard="ISO 10140-2", test_date="2026-07-18", laboratory="Phonometry Reference Laboratory", operator="José Manuel Requena Plens", report_id="PHN-2026-0042", requirement=42.0, # adds the PASS/FAIL verdict row ) building.weighted_rating(R).report( "Rw_fiche.pdf", metadata=metadata ) # Rw (C; Ctr) # Impact rating from a measured 16-band L'nT spectrum (ISO 717-2) l_nt = [45.0, 47.0, 48.0, 49.0, 51.0, 52.0, 53.0, 54.0, 55.0, 56.0, 57.0, 58.0, 55.0, 52.0, 49.0, 46.0] building.weighted_impact_rating(l_nt).report("Lnw_fiche.pdf") # Ln,w (CI) ``` Rendered examples of both fiches, regenerated with `make reports`, are kept in the repository. Click either preview to open the PDF: [![Airborne ISO 717-1 example report: metadata header, one-third-octave R table beside the measured-versus-shifted-reference plot, boxed Rw (C; Ctr) and a PASS verdict](https://raw.githubusercontent.com/jmrplens/phonometry/main/.github/reports/iso717_airborne_example.webp)](https://raw.githubusercontent.com/jmrplens/phonometry/main/.github/reports/iso717_airborne_example.pdf) *Airborne rating fiche (`WeightedRatingResult.report`), $R_\mathrm{w}\ (C\ ;\ C_\mathrm{tr})$.* [![Impact ISO 717-2 example report: the same accredited layout for the normalized impact level Ln, boxed Ln,w (CI) and a FAIL verdict](https://raw.githubusercontent.com/jmrplens/phonometry/main/.github/reports/iso717_impact_example.webp)](https://raw.githubusercontent.com/jmrplens/phonometry/main/.github/reports/iso717_impact_example.pdf) *Impact rating fiche (`ImpactRatingResult.report`), $L_\mathrm{n,w}(C_\mathrm{I})$.* ### Report metadata (`ReportMetadata`) Every field is optional and only the supplied ones are rendered, so the same object drives a full accredited fiche and a lightweight prediction fiche. The numeric fields are validated on construction by physical range. | Field | Type | Rendered as | | --- | --- | --- | | `specimen`, `client`, `mounted_by`, `manufacturer` | `str` | Header identity of the tested element and who it was tested for / mounted by | | `area`, `mass_per_area` | `float > 0` | Sample area $S$ (m²) and measured mass per unit area (kg/m²) | | `source_volume`, `receiving_volume` | `float > 0` | Room volumes (m³) | | `temperature_c`, `relative_humidity_percent` | `float` | Single representative climate: air temperature (°C, any sign), relative humidity (0–100 %) | | `static_pressure_kpa` | `float > 0` | Ambient (static) air pressure during the test (kPa) | | `source_temperature_c`, `source_relative_humidity_percent`, `receiving_temperature_c`, `receiving_relative_humidity_percent` | `float` | Per-room climate when source and receiving rooms are reported separately (same ranges as above) | | `test_room`, `mounting`, `measurement_standard`, `test_date` | `str` | Facility, mounting condition, the measurement standard (forms the standard-basis line) and the test date | | `laboratory`, `operator`, `report_id`, `notes` | `str` | Footer: institute, operator signature line, report number and free-form remarks | | `requirement` | `float` | Target single number; adds the verdict row (airborne passes at or above it, impact at or below it) | ## Quick answers ### What is the difference between the C and Ctr spectrum adaptation terms? Both re-rate the same measured curve against the two source spectra of ISO 717-1 Annex A: $C$ against A-weighted pink noise (living activities: speech, music, radio, television) and $C_\mathrm{tr}$ against A-weighted urban road traffic, whose energy sits at low frequency. $C$ is typically 0 to −2 dB, while a lightweight double leaf with a mass-air-mass resonance near 100 Hz can carry a $C_\mathrm{tr}$ of −5 to −10 dB. ## References - Hopkins, C. (2007). *Sound insulation*. Butterworth-Heinemann. ISBN 978-0-7506-6526-1. [doi:10.4324/9780080550473](https://doi.org/10.4324/9780080550473). The interpretation of the single-number ratings and what they hide about the underlying band spectra. - International Organization for Standardization. (2020). *Acoustics — Rating of sound insulation in buildings and of building elements — Part 1: Airborne sound insulation* (ISO 717-1:2020). [iso.org catalogue](https://www.iso.org/standard/77435.html). The airborne reference-curve rating and the spectrum adaptation terms interpreted above. - International Organization for Standardization. (2020). *Acoustics — Rating of sound insulation in buildings and of building elements — Part 2: Impact sound insulation* (ISO 717-2:2020). [iso.org catalogue](https://www.iso.org/standard/69867.html). The impact reference-curve rating and the CI adaptation term, with the enlarged-range CI,50-2500. ## Standards ISO 717-1:2020 and ISO 717-2:2020, which define the reference-curve single-number ratings, the spectrum adaptation terms $C$, $C_\mathrm{tr}$ and $C_\mathrm{I}$, the enlarged-range terms of Annex B / A.2.1 and the 0.1 dB-step variant used in uncertainty statements. The spectra they rate come from ISO 16283 (field), ISO 10140 (laboratory), ISO 15186 (intensity), ISO 10052 (survey) and ISO 10848 (flanking); conformance is anchored on the standards' own Annex C worked examples. **Not covered.** Nothing here measures: every function takes an already-measured or predicted band spectrum from the field, laboratory, intensity, survey or flanking guides. The façade single number of **ISO 16283-3** Annex F and the flanking $D_\mathrm{n,f,w}$ reuse these engines from their own pages rather than duplicating them. One member of the family is deliberately absent: the A-weighted maximum impact level of **ISO 717-2:2020 Annex D**, which rates the rubber ball and the bang machine. It shifts no curve at all (it is an energy sum of A-weighted band levels), so it belongs with the sources it rates, in [Heavy and soft impact sources](https://docs.jmrp.io/phonometry/buildings/insulation/heavy-impact-sources/). ## See also - [Linings, Floor Coverings, Joints and Rain (ISO 10140-1)](https://docs.jmrp.io/phonometry/buildings/insulation/lab-application-rules/): the improvements $\Delta R_\mathrm{w}$ and $\Delta L_\mathrm{w}$ rated on the reference curves of ISO 717-1 Table E.1 and ISO 717-2 Table 4. - [Field Insulation Measurement (ISO 16283)](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-field/): the airborne, impact and façade spectra these engines rate in the field. - [Laboratory Insulation Measurement](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-lab/): the laboratory $R$ and $L_\mathrm{n}$ behind $R_\mathrm{w}$ and $L_\mathrm{n,w}$. - [Sound Insulation by Intensity (ISO 15186)](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-intensity/): the intensity indices rated with the same airborne engine. - [Sound Insulation Survey Method (ISO 10052)](https://docs.jmrp.io/phonometry/buildings/insulation/insulation-survey/): the survey quantities and their automatic ratings. - [Laboratory Flanking Transmission (ISO 10848)](https://docs.jmrp.io/phonometry/buildings/insulation/flanking-lab/): the flanking descriptors $D_\mathrm{n,f,w}$ and $L_\mathrm{n,f,w}$. - [Floor-Covering Impact Improvement (ISO 16251-1)](https://docs.jmrp.io/phonometry/buildings/design/impact-improvement/): the weighted improvement $\Delta L_\mathrm{w}$ built on the ISO 717-2 reference floor. - [Predicting Sound Insulation (EN 12354)](https://docs.jmrp.io/phonometry/buildings/design/insulation-prediction/): the single-number model that consumes these ratings. - [Theory](https://docs.jmrp.io/phonometry/reference/theory/rooms-buildings/): the reference-curve derivation behind the weighted single-number ratings. - API reference: [`building.measurement.insulation`](https://docs.jmrp.io/phonometry/reference/api/building/insulation/).