Source: https://docs.jmrp.io/phonometry/start/guides/ Every guide on this site follows the same shape: the standard it implements, the quantities that standard defines, the assumptions the implementation makes, then runnable code and the figure it draws. Nothing here is a survey of the field; each page is the working documentation of a module, written so that a result can be defended clause by clause rather than trusted. This page is the map. A hundred and sixty-four guides sit in thirteen topics, and each topic has its own overview page with the longer story of how its pieces fit together. If you are arriving without a specific question, read [Getting Started](/phonometry/start/getting-started/) first: it runs one signal through the whole processing chain and gives the vocabulary the rest of the guides assume. If you already know the quantity you need, the [glossary](/phonometry/reference/glossary/) lists every symbol with its unit, its defining standard and the guide that implements it. Two pointers before the list. Function signatures live in the [API reference](/phonometry/reference/api/), which is generated from the docstrings and is not repeated here. Derivations, design decisions and the numerical evidence live in [Reference](/phonometry/reference/): the theory pages explain why a formula is the one it is, and the conformance report shows the standard's own expected value next to the computed one. A third pointer, for anyone arriving with a measurement to make rather than a number to compute. Where a method needs a physical arrangement, its guide carries an engineering setup diagram with the geometry the standard prescribes: source and microphone positions, separations, mounting, and the specimen or the enclosing surface. [Field Insulation Measurement](/phonometry/buildings/insulation/insulation-field/) draws the ISO 16283-1 room pair that way, and [Impedance Tube](/phonometry/materials/absorbers/impedance-tube/) draws the ISO 10534-2 tube with both microphone spacings. The prediction and rating guides take element or material data as their input instead and need no facility, which is usually the fastest way to tell the two kinds of page apart. [What do you need to measure?](/phonometry/start/tasks/) sorts the same guides by the job rather than by the topic. ## [Signal analysis](/phonometry/signals/) Filter banks, weighting, levels, spectra, calibration and uncertainty. This is the chain that turns a digital signal into a standards-compliant number, and every other area consumes it: a loudness model needs calibrated band levels, a room parameter needs a filtered impulse response, an environmental rating is an adjusted $L_\mathrm{eq}$. Implements IEC 61260-1, IEC 61260-3, ANSI S1.11, IEC 61672-1, IEC 61672-3, ISO 7196, IEC 61252, ISO 1996-1, IEC 60942, IEC 61183, IEC 62585, IEC 61094-2, IEC 61094-3, IEC 61094-5, IEC 61094-8 and the GUM. - [Build a sound level meter](/phonometry/signals/sound-level-meter/): the whole area assembled end to end on one runnable page, from the calibrator tone to the reported levels. **[Octave filtering](/phonometry/signals/filters/)** - [Filter Banks](/phonometry/signals/filters/filter-banks/): the fractional-octave band mathematics, the bank parameters, the parametric EQ, band decomposition and zero-phase offline filtering. - [Filter Architecture Gallery](/phonometry/signals/filters/filter-gallery/): the five filter architectures compared at the band edges, the full response gallery and per-architecture usage, with the Linkwitz-Riley crossover. - [Filter Class Verification (IEC 61260-1)](/phonometry/signals/filters/filter-compliance/): the Table 1 acceptance mask band by band, the effective bandwidth and the summation of outputs of IEC 61260-2, the swept time-invariance test, the grading of IEC 61260-3 periodic tests, the class 0 of the withdrawn 1995 edition and the compliance fiche. - [Block Processing](/phonometry/signals/filters/block-processing/): stateful streaming analysis that carries filter state across buffers, for signals that never fit in memory. - [Multichannel and Performance](/phonometry/signals/filters/multichannel/): vectorized analysis of many channels at once, with the (channels, samples) convention and performance notes. **[Levels and weighting](/phonometry/signals/levels/)** - [Frequency Weighting (A, C, Z)](/phonometry/signals/levels/weighting/): the IEC 61672-1 ear-response curves, the high-frequency accuracy mode and the Table 3 class verification. - [Special Weightings (G, B, D, AU)](/phonometry/signals/levels/special-weightings/): ISO 7196 G-weighting for infrasound, the historical B and D curves and AU for audible sound in the presence of ultrasound. - [Time Weighting](/phonometry/signals/levels/time-weighting/): the Fast, Slow and Impulse exponential ballistics of IEC 61672-1. - [Integrated and Statistical Levels](/phonometry/signals/levels/levels/): $L_\mathrm{eq}$ and $L_\mathrm{Aeq}$, the percentile levels $L_{10}$/$L_{50}$/$L_{90}$, $L_\mathrm{Cpeak}$ and SEL, and the noise dose. - [Environmental Levels (ISO 1996-1/-2)](/phonometry/environment/assessment/environmental-levels/): $L_\mathrm{den}$, $L_\mathrm{dn}$ and the composite rating levels, the tonal adjustment, the residual-noise correction and the uncertainty budget. It lives under Environment and transport, and is repeated here because it is the level definitions above aggregated over a day. - [Spanish Noise Regulation (RD 1367/2007)](/phonometry/environment/assessment/spanish-noise-regulation/): the corrected level $L_\mathrm{Keq}$ with its $K_\mathrm{t}$, $K_\mathrm{f}$ and $K_\mathrm{i}$ corrections, the evaluation periods and noise phases, the limit tables and the Article 25 compliance check. It lives under Environment and transport too. **[Signals and spectra](/phonometry/signals/spectra/)** - [Calibrated spectral analysis](/phonometry/signals/spectra/spectral-analysis/): the Welch power and cross-spectral estimators with their random errors, chi-square confidence intervals and fractional-octave smoothing. - [Multiple and partial coherence](/phonometry/signals/spectra/miso-coherence/): the ordinary, multiple and partial coherence of several correlated sources driving one response, and which source dominates each band. - [Time-frequency analysis](/phonometry/signals/spectra/time-frequency/): the calibrated STFT spectrogram in absolute dB SPL, and the zoom FFT that resolves tones closer than a practical FFT bin. - [Cepstrum, echoes and the envelope spectrum](/phonometry/signals/spectra/cepstrum-echoes/): quefrency analysis, echo detection with the reflection coefficient read off the cepstral peak, liftering and the envelope spectrum. - [Time synchronous averaging](/phonometry/signals/spectra/synchronous-averaging/): extraction of a periodic waveform of known period, the comb filter that describes it and the choice of the number of averages. - [Machine fault frequencies](/phonometry/vibration/machinery/machine-diagnostics/): the kinematic fault-frequency families of rotating machinery (Norton & Karczub Section 8.4) drawn on top of a measured envelope spectrum: bearing BPFO, BPFI, BSF and cage frequencies, gear-mesh sidebands, induction-motor slip, pole-pass and rotor-slot harmonics, and blade-passing tones. It lives under Vibration and structure-borne sound, and is repeated here because it is the envelope spectrum above put to work. - [Correlation, time delay and envelope](/phonometry/signals/spectra/correlation-delay/): correlation with its random errors, time-delay estimation by direct correlation and the GCC weightings, and the Hilbert envelope. - [Test signals and sample-rate tools](/phonometry/signals/spectra/test-signals/): IEC 60268-1 tone bursts with exact gating, colored noise with an exact slope, resampling with a stated anti-alias specification and fractional delay. - [System measurement](/phonometry/signals/spectra/system-measurement/): complementary Golay pairs, sweeps shaped to an arbitrary target magnitude spectrum, and Kirkeby-regularized inversion of a measured response. **[Calibration and uncertainty](/phonometry/signals/metrology/)** - [Calibration and dBFS](/phonometry/signals/metrology/calibration/): physical SPL calibration from a calibrator tone or a known sensitivity, and the digital full-scale mode. - [Compliance and verification](/phonometry/signals/metrology/compliance-verification/): what a performance class asserts, the verifiers per stage, the conformance report, and the scope of the pattern-evaluation and periodic-test parts. - [Measurement uncertainty (GUM and Monte Carlo)](/phonometry/signals/metrology/gum-uncertainty/): the law of propagation of uncertainty and the Monte Carlo method, with expanded uncertainty and coverage intervals. - [Data qualification](/phonometry/signals/metrology/data-qualification/): the reverse arrangement and runs tests for stationarity, and the Rice level-crossing and peak statistics with the irregularity factor. - [Random-Incidence and Diffuse-Field Response (IEC 61183)](/phonometry/signals/metrology/random-incidence/): the directivity factor of a sound level meter from readings in two planes, one plane or 38 equal-area elements, and its random-incidence and diffuse-field sensitivity levels. - [Free-Field Corrections of a Sound Level Meter (IEC 62585)](/phonometry/signals/metrology/free-field-corrections/): the adjustment value at the calibration check frequency, the corrections for a calibrator, a coupler and an actuator, their uncertainty budget and the maxima of clauses 9 to 14 as a verdict and a fiche. - [Periodic Tests of a Sound Level Meter (IEC 61672-3)](/phonometry/signals/metrology/sound-level-meter-periodic-tests/): the verdict on a laboratory's periodic-test results, clause by clause against the limits of IEC 61672-1 and the maxima of its Table B.1, and the statement of Clause 22. - [Microphone Calibration by Comparison (IEC 61094-5/-8)](/phonometry/signals/metrology/comparison-calibration/): a working standard microphone calibrated against a reference in a coupler or a free field, with the interchange of Annex C, the monitor of a substitution, the corrections, the validation of a jig or coupler and the budgets of Table D.1 and Table 2. - [Microphone Calibration by Reciprocity (IEC 61094-2/-3)](/phonometry/signals/metrology/reciprocity-calibration/): laboratory standard microphones calibrated in pairs with no reference, in a coupler with its heat-conduction and capillary corrections or in a free field with its attenuation and acoustic centres, and the budgets of Table 1. ## [The medium](/phonometry/fluids/) The fluid the sound travels through, computed from the conditions that were measured rather than assumed. A density and a speed of sound stand behind every level in the library, and this is where they come from instead of being typed once. Sits with the filters, the signal analysis and the metrology in the transverse toolbox, because a medium is not a subject some domains have and others do not. Implements IEC 61094-2:2009 Annex F (CIPM-2007). - [Humid air](/phonometry/fluids/humid-air/): the density, speed of sound, ratio of specific heats, viscosity and thermal diffusivity of air from the measured temperature, pressure and humidity, what each condition is worth, the domain the annex states for itself, and what the model refuses to guess. ## [Elastic solids](/phonometry/solids/) The elastic constants of a solid and the three longitudinal wave speeds that follow from them, named after the shape the wave travels in. A plate table and a solver table print different numbers for the same steel, and the conversion between them is written here once instead of in each caller's head. - [Wave speeds](/phonometry/solids/wave-speeds/): the beam, plate and unbounded longitudinal speeds, the inverse that turns each back into a Young's modulus, and the thickness-critical-frequency product that lets two books be checked against each other for free. ## [Files](/phonometry/io/) Measurement audio in and out. The file layer of the signal chain: every linear WAV a sound level meter or field recorder writes comes back as a calibrated `Signal` with its `bext` provenance, long recordings stream through the stateful filters block by block, and what leaves the library is a BWF with its provenance and a sidecar carrying the calibration. Implements EBU Tech 3285 and ITU-R BS.2088; FLAC archives follow RFC 9639. A catalogue of materials of your own, from a data sheet or a test report, is read from a JSON file, or from a spreadsheet saved as CSV, into the rows every published catalogue hands out. - [Reading and writing measurement audio](/phonometry/io/audio-files/): the whole workflow on one runnable page, from the meter's WAV to the calibrated level, the lossy warning, streaming, BWF writing, the sidecar and lossless conversion. - [Your own catalogues](/phonometry/io/material-catalogues/): a data sheet, a test report or a measurement of yours as a catalogue file, read into the rows every published catalogue hands out, searched with the same lookups, handed to the same models and completed in your editor with its JSON Schema. ## [Hearing and perception](/phonometry/perception/) Loudness, sound quality, speech intelligibility, hearing and exposure. Where the core area asks how much sound there is, this one asks what a listener makes of it: how loud it seems, how sharp or rough or annoying, how much of a talker survives the room, and how much hearing a working life in that noise costs. Implements ISO 532-1/-2/-3, ECMA-418-1/-2, ISO 226, DIN 45692, IEC 60268-16, ANSI S3.5, DIN 45681, ISO/PAS 20065, ISO 7029, ISO 389-7, ISO 8253-1/-2, ISO 1999, ISO 9612 and ISO 4869-1/-2/-3/-6. **[Psychoacoustics](/phonometry/perception/psychoacoustics/)** - [Loudness](/phonometry/perception/psychoacoustics/loudness/): loudness in sones by the ISO 532-1 Zwicker method with its one-page fiche, plus the ISO 226 equal-loudness contours. - [Advanced Loudness (ISO 532-2/-3, ECMA-418-2)](/phonometry/perception/psychoacoustics/advanced-loudness/): the Moore-Glasberg stationary and time-varying methods and the Sottek Hearing Model loudness, with the model-choice table. - [Sound Quality Metrics](/phonometry/perception/psychoacoustics/sound-quality/): sharpness in acum, and the ECMA-418-2 tonality, roughness and fluctuation strength. - [Prominent Discrete Tones (ECMA-418-1)](/phonometry/perception/psychoacoustics/tone-prominence/): the tone-to-noise ratio and prominence ratio, with their frequency-dependent prominence criteria. - [Objective audibility of tones in noise (ISO/PAS 20065)](/phonometry/perception/psychoacoustics/tone-audibility/): the critical-band masking level, the masking index and the audibility of a tone above the masking threshold. - [Psychoacoustic annoyance and fluctuation strength](/phonometry/perception/psychoacoustics/psychoacoustic-annoyance/): the Fastl and Zwicker annoyance model built from loudness, sharpness, roughness and fluctuation strength. **[Speech](/phonometry/perception/speech/)** - [Speech Transmission Index (STI)](/phonometry/perception/speech/speech-transmission/): the modulation transfer function, the indirect method from an impulse response and the direct STIPA measurement. - [Speech Intelligibility Index](/phonometry/perception/speech/speech-intelligibility/): the SII in all four of the standard's band procedures, with the band-importance functions, self-masking and upward spread of masking. - [Objective Intelligibility (STOI and ESTOI)](/phonometry/perception/speech/objective-intelligibility/): the two correlation-based measures for time-frequency weighted noisy speech. **[Hearing and exposure](/phonometry/perception/hearing/)** - [Hearing threshold (age and reference zero)](/phonometry/perception/hearing/hearing-threshold/): the age-related threshold distribution of ISO 7029 and the ISO 389-7 reference threshold of hearing. - [Audiometric Test Methods (ISO 8253-1 and -2)](/phonometry/perception/hearing/audiometry/): whether the test room is quiet enough and its sound field free, quasi-free or diffuse, the rules that turn responses into a hearing threshold level, and its uncertainty. - [Noise-induced hearing loss (ISO 1999)](/phonometry/perception/hearing/noise-induced-hearing-loss/): the permanent threshold shift as a function of level, duration and frequency, combined with the age component. - [Occupational Noise Exposure (ISO 9612)](/phonometry/perception/hearing/occupational-exposure/): the task-based, job-based and full-day strategies for $L_\mathrm{EX,8h}$, with the uncertainty budget and the upper limit. - [Hearing Protectors (ISO 4869-1, -2, -3 and -6)](/phonometry/perception/hearing/hearing-protectors/): the attenuation measured on sixteen subjects with its uncertainty and its significance test, the octave-band, HML and SNR methods that say what a protector leaves at the ear, what an active noise reduction earmuff adds, and the insertion loss that screens an earmuff on a test fixture. ## [Rooms and buildings](/phonometry/buildings/) Room parameters, background noise, field and laboratory insulation, and prediction from element data. Two questions run through the area: how a room treats the sound made inside it, and how much of the sound made next door gets through. Implements ISO 3382-1/-2/-3, ISO 14257, ISO 11690-3, ISO 16283-1/-2/-3, ISO 10140, ISO 10848, ISO 15186-1/-2, ISO 16251-1, ISO 717-1/-2, EN 12354-1 to -6, ISO 18233, ISO 12999-1, ISO 10052, ISO 16032 (from the ISO/DIS 16032:2023 draft), ANSI/ASA S12.2 and ASTM E413. **[Room acoustics](/phonometry/buildings/rooms/)** - [Measuring the Room Impulse Response](/phonometry/buildings/rooms/room-impulse-response/): the ISO 18233 deterministic acquisition, exponential sweeps with their deconvolution, and MLS. - [Room Acoustics](/phonometry/buildings/rooms/room-acoustics/): the room parameters EDT, $T_{20}$, $T_{30}$, $C_{50}$, $C_{80}$, $D_{50}$ and $T_\mathrm{s}$ derived from that impulse response. - [Sound strength G (ISO 3382-1)](/phonometry/buildings/rooms/sound-strength/): one of the two auditorium measures that need a calibrated source, and the three printed routes to its free-field reference at 10 m. - [Spatial impression (ISO 3382-1)](/phonometry/buildings/rooms/spatial-impression/): the early lateral energy fraction, the late lateral sound level and the interaural cross correlation, measured with a second microphone. - [Stage support and uncertainty (ISO 3382-1)](/phonometry/buildings/rooms/stage-and-uncertainty/): what a player hears of their own instrument on the platform, and what the randomness of the excitation costs a reverberation time. - [Reporting and source qualification (ISO 3382-1)](/phonometry/buildings/rooms/reporting-and-qualification/): the printed tables, from the directivity a source must clear to the fifteen items a test report shall carry. - [Open-Plan Office Acoustics (ISO 3382-3)](/phonometry/buildings/rooms/open-plan-acoustics/): the spatial decay rate of speech and the distraction and privacy distances of an open-plan floor. - [Image sources and the steady-state room field](/phonometry/buildings/rooms/room-image-sources/): the deterministic image-source impulse response of a rectangular room, the room constant, critical distance and Schroeder frequency. - [Spatial Sound Decay in Workrooms](/phonometry/buildings/rooms/workroom-sound-decay/): how far the level falls as you walk away from a machine, the excess over a free field, and the prediction categories that match the data you have. - [Room-noise criteria (NC / RC Mark II)](/phonometry/buildings/rooms/room-noise/): the ANSI/ASA S12.2 Noise Criteria rating by tangency, and the Room Criteria Mark II rating with its rumble, hiss or neutral tag. - [Reverberation-time prediction (Sabine, Eyring, Arau)](/phonometry/buildings/rooms/reverberation-prediction/): five statistical-acoustics models from volume, boundary areas and surface absorption, including the air term. - [Sound absorption in enclosed spaces (EN 12354-6)](/phonometry/buildings/rooms/enclosed-space-absorption/): the total equivalent absorption area of a room from its surfaces, objects and air, and the reverberation time that follows. **[Sound insulation](/phonometry/buildings/insulation/)** - [Field Insulation Measurement (ISO 16283)](/phonometry/buildings/insulation/insulation-field/): airborne and impact insulation measured in the building, its test report and the ISO 12999-1 uncertainty that qualifies it. - [Small Rooms: the ISO 16283 Low-Frequency Procedure](/phonometry/buildings/insulation/low-frequency-procedure/): the corner measurement ISO 16283 makes mandatory below 25 m³, and the 63 Hz octave reverberation time that comes with it. - [Laboratory Insulation Measurement](/phonometry/buildings/insulation/insulation-lab/): the ISO 10140 characterisation of an element with flanking suppressed. - [Linings, Floor Coverings, Joints and Rain (ISO 10140-1)](/phonometry/buildings/insulation/lab-application-rules/): the improvement a lining or a floor covering gives the element it is laid on, rated on the ISO 717 reference curves, the sound reduction index of a sealed joint per metre, the forms of Figures H.4 and J.7, and the sound of artificial rain on a roof or a rooflight. - [Sound Insulation by Intensity (ISO 15186)](/phonometry/buildings/insulation/insulation-intensity/): the transmitted power read off the radiating face, for the whole element or element by element. - [Sound Insulation Survey Method (ISO 10052)](/phonometry/buildings/insulation/insulation-survey/): the octave-band control method with its reverberation index and its airborne, impact, façade and service-equipment quantities. - [Service-Equipment and Activity Noise (ISO 16032)](/phonometry/buildings/insulation/service-equipment-noise/): the engineering method for the sound of a building's equipment and of activities in or near it, from the ISO/DIS 16032:2023 draft. - [Laboratory Flanking Transmission (ISO 10848)](/phonometry/buildings/insulation/flanking-lab/): the junction vibration reduction index and the flanking level differences measured on a test facility. - [Heavy and Soft Impact Sources (ISO 16283-2)](/phonometry/buildings/insulation/heavy-impact-sources/): the rubber ball and the bang machine: the impact force exposure level that specifies them, the laboratory check they have to pass, and the single number of ISO 717-2 Annex D. - [Insulation Ratings (ISO 717)](/phonometry/buildings/insulation/insulation-ratings/): the airborne and impact reference-curve engines with $C$, $C_\mathrm{tr}$ and $C_\mathrm{I}$, the enlarged-range terms and the ISO 717 fiche. - [Façade Sound Insulation](/phonometry/buildings/insulation/facade-insulation/): the building envelope measured per ISO 16283-3, predicted per EN 12354-3 and radiating outwards per EN 12354-4. - [Spanish Building Code (CTE DB-HR)](/phonometry/buildings/insulation/spanish-building-code/): the DB-HR global indices $R_\mathrm{A}$, $R_\mathrm{A,tr}$, $D_{\mathrm{n}T,\mathrm{A}}$ and $D_{2\mathrm{m,n}T,\mathrm{Atr}}$, the clause 2 requirement tables and the window-size correction. **[Insulation design](/phonometry/buildings/design/)** - [Predicting Sound Insulation (EN 12354)](/phonometry/buildings/design/insulation-prediction/): in-situ airborne and impact insulation between rooms from element data, with their flanking paths. - [Detailed Per-Band Prediction (ISO 12354)](/phonometry/buildings/design/detailed-prediction/): the same prediction band by band rather than as one number: in-situ element and junction data, the flanking index and impact level, and the per-path contributions behind R'w and L'n,w. - [Predicting Panel Sound Insulation](/phonometry/buildings/design/panel-sound-insulation/): the mass law and coincidence dip, double walls, slits and apertures, plate radiation efficiency and point mobilities. - [Floor-Covering Impact Improvement (ISO 16251-1)](/phonometry/buildings/design/impact-improvement/): the weighted improvement of a soft floor covering measured on a small heavyweight mock-up. - [Predicting Resilient-Layer Performance](/phonometry/buildings/design/resilient-layers/): the tapping-machine force model, the cut-off frequency of a soft covering, the floating-floor improvement laws and the ISO 12354-1 Annex D rating of a wall lining. - [Dynamic stiffness of resilient materials (EN 29052-1)](/phonometry/materials/resilient/dynamic-stiffness/): the stiffness per unit area under a floating floor from the load-plate resonance, with the enclosed-gas term. It lives under Materials and surfaces, and is repeated here because it is the input the layer models above ask for. - [Structure-borne sound power of equipment (EN 15657)](/phonometry/buildings/design/structure-borne-power/): the reception-plate method and the plate-independent source quantities: equivalent blocked force, free velocity and source mobility. Also listed under Vibration, beside the mobilities it is built from. - [Installed structure-borne sound (EN 12354-5)](/phonometry/buildings/design/installed-structure-borne/): the coupling term from source and receiver mobilities, the installed power and the per-path sound pressure level in the receiving room. Also listed under Vibration. ## [Materials and surfaces](/phonometry/materials/) Absorption, airflow resistance, the impedance tube, porous and metamaterial models, diffusers and scattering. What a surface does to the sound that reaches it, measured in a laboratory or predicted from the material parameters. Implements ISO 354, ISO 11654, EN 16487, ISO 10534-1/-2, ISO 9053-1/-2, ISO 17497-1/-2, ISO 13472-1/-2, EN 29052-1 and ISO 12999-2. - [Reading a material datasheet](/phonometry/materials/reading-a-datasheet/): what the numbers on a data sheet or a test report are before you type them: the practical against the one-third-octave coefficient, a declared level, the mounting and the revision, and the sound reduction index and impact improvement of a laboratory report, each rated again from its bands. **[Absorbers](/phonometry/materials/absorbers/)** - [Sound Absorption Measurement and Rating](/phonometry/materials/absorbers/absorption-measurement/): the ISO 354 reverberation-room measurement, the weighted rating and its class, and the measurement uncertainty of both. - [Suspended Ceilings: the EN 16487 Test Code](/phonometry/materials/absorbers/suspended-ceilings/): the specimen size, the mounting depth and the air-absorption cap that make one ceiling measurement comparable with another. - [Airflow Resistance](/phonometry/materials/absorbers/airflow-resistance/): the static and alternating determination of airflow resistance and resistivity. - [Impedance Tube](/phonometry/materials/absorbers/impedance-tube/): the normal-incidence surface impedance, absorption and transmission loss, plus the virtual FDTD tube. - [Porous and Multilayer Absorbers](/phonometry/materials/absorbers/porous-absorbers/): the Delany-Bazley, Miki and Johnson-Champoux-Allard models, the transfer-matrix multilayer solver with perforated, microperforated and membrane layers, and the random-incidence integral. - [Metamaterial Absorbers](/phonometry/materials/absorbers/metamaterial-absorbers/): the critical-coupling condition for perfect absorption and the slow-sound slit panel loaded by Helmholtz resonators, with its design solver. **[Diffusers and surfaces](/phonometry/materials/diffusers/)** - [Diffusers and Their Coefficients](/phonometry/materials/diffusers/diffusers/): the random-incidence scattering coefficient, the autocorrelation diffusion coefficient, and Schroeder design with its far-field prediction. - [Metadiffusers](/phonometry/materials/diffusers/metadiffusers/): deep-subwavelength Schroeder diffusers from resonator-loaded slits, slow sound and ternary sequences. - [In-situ Road-Surface Absorption](/phonometry/materials/surfaces/road-absorption/): in-situ road-surface absorption by the subtraction technique and the spot method. It is the only guide of the [surfaces measured in place](/phonometry/materials/surfaces/) overview, which the sidebar files in this same group. **[Resilient layers](/phonometry/materials/resilient/)** - [Dynamic stiffness of resilient materials (EN 29052-1)](/phonometry/materials/resilient/dynamic-stiffness/): the stiffness per unit area under a floating floor from the load-plate resonance, with the enclosed-gas term. Also listed under Rooms and buildings, beside the floating-floor prediction that consumes it. ## [Vibration and structure-borne sound](/phonometry/vibration/) Mobility and frequency-response functions, isolators, radiated power, junctions and human vibration. The area covers the path a machine takes into a structure and out again as airborne sound, and the separate question of what vibration does to the person exposed to it. Implements ISO 7626-1/-2/-5, ISO 10846-1/-2/-3/-4/-5, ISO 9611, ISO/TS 7849-1/-2, EN 15657, EN 12354-5, ISO 2631-1/-2/-4/-5, ISO 5349-1/-2, ISO 8041-1/-2 and DIN 4150-3. **[Structure-borne sources](/phonometry/vibration/structural/)** - [Mechanical mobility and the FRF family (ISO 7626-1)](/phonometry/vibration/structural/mechanical-mobility/): receptance, mobility and accelerance with their reciprocals, conversion between them, and the closed-form single-degree-of-freedom resonator. - [Mobility by impact excitation (ISO 7626-5)](/phonometry/vibration/structural/impact-mobility/): the mobility measured with an impact hammer: the force and exponential windows, the average over impacts with its coherence, the damping the window adds taken away by Annex A, and verdicts on double hits, the force spectrum, overload and the response decay. - [Bending-wave transmission at plate junctions](/phonometry/vibration/structural/junction-transmission/): the wave-approach transmission coefficients for rigid X, T, L and in-line junctions, their diffuse-field average, and the coupling loss factor and vibration reduction index. - [Transfer stiffness of resilient elements (ISO 10846)](/phonometry/vibration/structural/transfer-stiffness/): the dynamic transfer stiffness and loss factor of an isolator by the direct, indirect and driving-point methods, averaged into one-third-octave bands, with the adequacy checks of the rig and the Annex B uncertainty budget. - [Vibration damage to structures (DIN 4150-3)](/phonometry/vibration/structural/structural-damage/): the guideline peak particle velocities a foundation, a topmost floor plane and a buried pipe are judged by, and the bending stress a velocity implies. - [Predicting a building's own frequency (ISO 4866)](/phonometry/vibration/structural/building-response/): the empirical predictors of Annex D, the ± 50 % they admit, and the damping range the annex reports without a way to predict it. - [Sound power from surface vibration (ISO/TS 7849)](/phonometry/devices/emission/vibration-sound-power/): the radiated power from the surface-averaged velocity level and the radiation factor, with the Part 1 upper limit and the Part 2 engineering value. It lives under Sources and devices, and is repeated here because its input is a measured surface velocity. - [Structure-borne sound power of equipment (EN 15657)](/phonometry/buildings/design/structure-borne-power/): the reception-plate method and the plate-independent source quantities, equivalent blocked force, free velocity and source mobility. It lives under Rooms and buildings, and is repeated here because the source quantities are mobilities. - [Installed structure-borne sound (EN 12354-5)](/phonometry/buildings/design/installed-structure-borne/): the coupling term from source and receiver mobilities, the installed power and the per-path sound pressure level in the receiving room. It lives under Rooms and buildings, for the same reason. **[Human vibration](/phonometry/vibration/human/)** - [Human Vibration](/phonometry/vibration/human/human-vibration/): whole-body and hand-arm exposure with the ISO 8041-1 weightings, the weighted r.m.s. and dose measures, and the daily exposure $A(8)$. - [Multiple-shock whole-body vibration (ISO 2631-5)](/phonometry/vibration/human/multiple-shock-vibration/): the seat-to-spine transfer function, the acceleration dose, and the cumulative stress variable behind the lumbar injury probability. - [What a seat does to the vibration (ISO 10326-1)](/phonometry/vibration/human/seat-vibration/): the SEAT factor of a laboratory seat test, the correction to the intended input and the transmissibility at resonance. - [Verifying a human-vibration meter (ISO 8041-1)](/phonometry/vibration/human/meter-verification/): the tolerance band on each frequency weighting, the characteristic phase deviation, the running r.m.s. decay and the saw-tooth burst indications, and the personal vibration exposure meter of ISO 8041-2 graded with the same burst tables. **[Machinery](/phonometry/vibration/machinery/)** - [Evaluating machine vibration](/phonometry/vibration/machinery/machine-vibration-evaluation/): grading a machine from one broad-band measurement into the four evaluation zones of ISO 20816-1, with the frequency-shaped velocity criterion, the vector reading of a change that a magnitude comparison misses, and the printed boundaries and ALARM and TRIP settings ISO 10816-3 gives for industrial machines. - [Machine fault frequencies](/phonometry/vibration/machinery/machine-diagnostics/): the characteristic bearing, gear and shaft frequencies and the envelope analysis that finds them under the broadband noise of a running machine. Also listed under Signal analysis, beside the spectral estimators it uses. **[Vibration immission](/phonometry/vibration/immission/)** - [Measuring vibration immission (DIN 45669-1)](/phonometry/vibration/immission/vibration-meter/): the vibration meter DIN 4150-2 and DIN 4150-3 presuppose, with the KB weighting, the weighted vibration severity and the clock maximum r.m.s. a measurement is reported in, the tolerance bands a meter is graded by, and the Annex E assessment velocity that judges a building without a dominant frequency. - [Vibration next to a railway (DIN 45672)](/phonometry/vibration/immission/railway-vibration/): one train passage reduced the way DIN 45672-2 reduces it, from the event value of an hour of traffic to the third-octave spectra and the narrow-band density behind them, and the ground constants of DIN 45672-1 from two wave speeds. - [Vibration and people in buildings (DIN 4150-2)](/phonometry/vibration/immission/people-in-buildings/): the guide values of Table 1 by area and time of day, the order DIN 4150-2 reads them in, the assessment vibration severity that sums a day of exposure into one number, the rules for blasting, roads, railways and construction sites, and the estimate from a peak velocity where nothing weighted was recorded. - [Railway vibration by category of train (E DIN 4150-2)](/phonometry/vibration/immission/railway-categories/): the draft that is to replace DIN 4150-2, one clock interval per passage, a weighting factor per kind of train, the night-time upper value of a new line and the 25 % rule of an altered one, with the rest of its changes behind an edition switch. - [Predicting railway vibration (E DIN 45672-3)](/phonometry/vibration/immission/railway-prediction/): the additive chain from an emission spectrum through the ground and the building to a third-octave spectrum on a floor, the six transfer tables of Annex A, and the KB values formed from the spectrum. - [Predicting vibration before measuring (DIN 4150-1)](/phonometry/vibration/immission/vibration-prediction/): the decay with distance beyond the far field with an exponent by kind of source and wave, what a foundation and a floor do, a blast, a falling mass and a hall of machines, and what a track excites at. ## [Environment and transport](/phonometry/environment/) Outdoor propagation, barriers, refraction, road, rail and wind-turbine sources, and the assessment built on them. Everything here concerns sound that has to travel a long way before it is assessed, so the atmosphere, the ground and the source's own motion all enter the answer. Implements ISO 9613-1/-2, ISO 17534-1, ISO 1996-1/-2, ISO/PAS 1996-3, NT ACOU 112, ISO 13474, ISO/TS 12913-2/-3, CNOSSOS-EU (2002/49/EC Annex II), EN 1793-1/-2/-3/-5, EN 16272-3-1, ISO 11819-1, ISO 3095, EN 15610, EN 15461, IEC 61400-11 and IEC TS 61400-11-2. One scope boundary is worth stating here rather than one click away. Of CNOSSOS-EU, what is implemented is the **source** side of Annex II: the road emission of section 2.2 with the Appendix F coefficients, and the railway emission of section 2.3 with Appendix G, which give the directional sound power per metre of source line. The propagation calculation of section 2.5, with its own ground, diffraction and favourable-conditions machinery, is **not** implemented; outdoor attenuation here goes through the ISO 9613-2 chain instead, which is a different model and not interchangeable with it for regulatory mapping. **[Outdoor sound](/phonometry/environment/propagation/)** - [Outdoor Sound Propagation](/phonometry/environment/propagation/outdoor-propagation/): atmospheric absorption and the ISO 9613-2 general method, with a per-term octave-band attenuation breakdown. - [Spherical ground effect and advanced barriers](/phonometry/environment/propagation/ground-barriers/): the Weyl-Van der Pol reflection coefficient over finite-impedance ground, and wave-theoretic barrier diffraction. - [Atmospheric refraction: rays and the GFPE](/phonometry/environment/propagation/atmospheric-refraction/): effective sound-speed profiles, curved rays with a closed-form shadow-zone distance, and the GFPE relative-level field. - [Sound reflection of a noise barrier in situ](/phonometry/environment/propagation/barrier-reflection/): the sound reflection index of EN 1793-5 from the impulse responses of the nine-microphone grid, its single number DL_RI and the low frequency limit a sample's size sets. - [Quality of Outdoor Sound Software (ISO 17534-1)](/phonometry/environment/propagation/software-quality/): a program's results against its certified test-case results, and the 0,1- and 0,9-quantiles of what a faster modified configuration costs. **[Sources](/phonometry/environment/sources/)** - [CNOSSOS-EU road traffic source emission](/phonometry/environment/sources/cnossos-road-emission/): the common EU road source of Annex II 2.2: rolling and propulsion sound power per vehicle category and the directional power per metre of source line. - [Road-surface noise: the statistical pass-by method](/phonometry/environment/sources/road-surface-pass-by/): what a road surface adds to the traffic on it, from the maximum level of each passing vehicle against its speed to the Statistical Pass-By Index of ISO 11819-1 and its difference from a reference surface. - [CNOSSOS-EU railway source emission](/phonometry/environment/sources/cnossos-rail-emission/): the rail source of Annex II 2.3: roughness and the contact filter, impact noise, curve squeal, traction and aerodynamic noise, and the two equivalent source lines. - [Railway rolling-stock noise: the ISO 3095 type test](/phonometry/environment/sources/rolling-stock-noise/): the stationary, constant-speed, starting and braking tests of a railway vehicle, the pass-by level and the transit exposure level, and the reference track judged by the rail roughness of EN 15610 and the decay rates of EN 15461. - [Wind-turbine noise: sound power and tonal audibility](/phonometry/environment/sources/wind-turbine-noise/): the apparent sound power level referred to the rotor centre, and the tonal audibility chain that decides whether a tone is audible. - [Wind turbine sound at a dwelling (IEC TS 61400-11-2)](/phonometry/environment/sources/wind-turbine-receptor/): what arrives at the receptor: the wind speed between heights, the bin averages and the background correction, the low frequency level indoors, the emergence, the amplitude modulation rating checked against the IOA code, and the rating level. **[Assessment and regulation](/phonometry/environment/assessment/)** - [Impulsive-sound prominence (NT ACOU 112)](/phonometry/environment/assessment/impulsive-sound/): the predicted prominence of each impulse from its onset rate and level difference, and the adjustment added to $L_\mathrm{Aeq}$. - [Impulsive Sound Exposure Statistics (ISO 13474)](/phonometry/environment/assessment/sel-distribution/): how often a distant blast is how loud: the long-term and rating levels, the ordered classes, the spread for turbulence and the exceedance levels. - [Soundscape Analysis (ISO/TS 12913)](/phonometry/environment/assessment/soundscape/): how people hear a place: the questionnaire and its scale values, the pleasantness and eventfulness of Figure A.1, the correlations with the acoustic data and the binaural metrics of Table D.1 at both ears. - [Environmental Levels (ISO 1996-1/-2)](/phonometry/environment/assessment/environmental-levels/): $L_\mathrm{den}$, $L_\mathrm{dn}$ and the composite rating levels, the tonal adjustment, the residual-noise correction and the uncertainty budget. Also listed under Signal analysis, beside the level definitions it builds on. - [Spanish Noise Regulation (RD 1367/2007)](/phonometry/environment/assessment/spanish-noise-regulation/): the corrected level $L_\mathrm{Keq}$ with its $K_\mathrm{t}$, $K_\mathrm{f}$ and $K_\mathrm{i}$ corrections, the evaluation periods and noise phases, the limit tables and the Article 25 compliance check. Also listed under Signal analysis, for the same reason. ## [Aircraft noise](/phonometry/aircraft/) Certification levels, airport contours and the rotorcraft hemisphere method: the noise of flight measured the way the certification and airport-planning documents prescribe. Implements ICAO Annex 16, IEC 61265, SAE ARP 866A/5534, ISO 3891 and ECAC Doc 29/32. - [Aircraft noise: Effective Perceived Noise Level](/phonometry/aircraft/aircraft-noise/): perceived noisiness and PNL, the tone correction, the duration correction and the measurement-system verifier. - [Airport Noise (ECAC Doc 29)](/phonometry/aircraft/airport-noise/): the noise-power-distance engine, the per-segment single-event chain and the ground-grid SEL contour. - [Rotorcraft noise: the hemisphere method](/phonometry/aircraft/rotorcraft-noise/): the hemisphere source model with its propagation adjustments, flight-condition interpolation, and the single-event contours. - [The ANP fleet database](/phonometry/aircraft/anp-fleet/): the EASA tables of noise-power-distance curves and default trajectories, and the Doc 29 chain run from an aircraft identifier. - [NPD data for the air at the airport](/phonometry/aircraft/npd-atmosphere/): the ANP curves recalculated for the temperature, humidity and pressure of a study by Doc 29 Appendix D, with SAE ARP 5534 or SAE ARP 866A absorption. ## [Underwater acoustics](/phonometry/underwater/) Levels referenced to 1 micropascal, ship radiated noise, pile driving, ambient noise and propagation loss. The reference quantities differ from the airborne ones, so this is the one area where a level cannot be read across without conversion. Implements ISO 18405, ISO 17208-1/-2, ISO 18406 and JOMOPANS-ECHO. - [Underwater acoustics: radiated noise and pile driving](/phonometry/underwater/underwater-acoustics/): the ISO 18405 reference levels, the ship radiated noise level and equivalent monopole source level, and single-strike and cumulative pile-driving exposure. - [Underwater sound propagation](/phonometry/underwater/underwater-propagation/): spreading plus volume absorption, the speed of sound in sea water, the sonar equation, seabed reflection loss and the ambient-noise spectrum. - [Underwater propagation solvers](/phonometry/underwater/underwater-solvers/): the normal-mode, ray-tracing, Gaussian beam and parabolic-equation solvers of the stratified waveguide, and how to choose a propagation model. - [Marine-mammal noise exposure](/phonometry/underwater/marine-mammal-exposure/): the hearing side of that noise: the group audiograms, the regulatory weighting functions with their guidance version, and the exposure of a pile-driving campaign against the injury criteria. ## [Sources and devices](/phonometry/devices/) Sound power, intensity, emission declarations, electroacoustics and programme loudness. What a source emits rather than what a receiver gets, plus the electroacoustic chain that reproduces or measures it. Implements ISO 3741, ISO 3743-1/-2, ISO 3744/3746, ISO 3745, ISO 26101, ISO 6926, ISO 9614-1/-2/-3, IEC 61043, ISO 4871, IEC 60268-1/-3/-4/-5/-7, IEC 60118-4, IEC 62489-1, ITU-R BS.1770-5 and EBU R 128. **[Sound power and intensity](/phonometry/devices/emission/)** - [Sound Intensity (p-p)](/phonometry/devices/emission/intensity/): two-microphone intensity with the field indicators that qualify the measurement. - [Sound Power](/phonometry/devices/emission/sound-power/): choosing the determination method and declaring the noise emission per ISO 4871. - [Sound Power by Pressure Methods](/phonometry/devices/emission/sound-power-pressure/): the enveloping surface of ISO 3744/3746 and the precision anechoic grade of ISO 3745. - [Free Field and Reference Sources](/phonometry/devices/emission/free-field-qualification/): the ISO 26101 inverse-square-law qualification of an anechoic or hemi-anechoic room against the Annex A that Amendment 1:2017 wrote into ISO 3745, and the calibration and requirements of an ISO 6926 reference sound source. - [Sound Power in the Reverberation Room](/phonometry/devices/emission/sound-power-reverberation/): the direct and comparison methods of ISO 3741. - [Sound Power in Small Test Rooms](/phonometry/devices/emission/sound-power-test-rooms/): the ISO 3743 methods for small movable sources, a comparison in a hard-walled room and a special reverberation room read directly or against a reference source. - [Sound Power in Situ by Comparison](/phonometry/devices/emission/sound-power-in-situ/): the ISO 3747 comparison against a reference sound source where the machine works, with the sound energy level of an impulsive source. - [Sound Power in a Duct](/phonometry/devices/emission/sound-power-in-duct/): the ISO 5136 in-duct method for fans, with the sampling-tube flow and modal correction of Annex A and the plane-wave relation of clause 8. - [Sound Power of Multisource Industrial Plants](/phonometry/devices/emission/sound-power-plant/): the ISO 8297 contour round a whole industrial plant, with the area, proximity and air absorption terms of clause 10 and the uncertainty of Table 1. - [Sound Power in the 16 kHz Octave](/phonometry/devices/emission/sound-power-high-frequency/): the four ISO 9295 methods above the range of ISO 3741 and ISO 3744, with the room constant from the reverberation time or from the air absorption, and the comparison for tones. - [Sound Power of Steam Turbine Sets](/phonometry/devices/emission/sound-power-turbines/): the IEC 61063 test code for a turbine set in its hall, with the stepped surface 1 m out, the key positions of Figure 2, the stepped background correction of Table 2 and the report of clause 10. - [Sound Power by Intensity Scanning](/phonometry/devices/emission/sound-power-intensity/): the on-site scanning of ISO 9614-2 and the ISO 9614-3 precision grade. - [Emission Sound Pressure at a Work Station](/phonometry/devices/emission/workstation-emission/): the ISO 11200 group, which turns a reading at the operator's position into what the machine alone puts there: the background correction with this group's own thresholds, the piecewise local environmental correction and its two routes, and the 4 dB boundary between grade 2 and grade 3. - [Sound power from surface vibration (ISO/TS 7849)](/phonometry/devices/emission/vibration-sound-power/): the surface-velocity route, for the machine that cannot be moved into a qualified room: the radiated power from the surface-averaged velocity level and the radiation factor, with the Part 1 upper limit and the Part 2 engineering value. Also listed under Vibration. **[Electroacoustics](/phonometry/devices/electroacoustics/)** - [Electroacoustics: distortion and frequency response](/phonometry/devices/electroacoustics/electroacoustics/): harmonic and intermodulation distortion, THD+N and SINAD, dynamic range and the $H_1$/$H_2$ frequency-response estimators. - [Loudspeaker Characterisation (IEC 60268-5)](/phonometry/devices/electroacoustics/loudspeakers/): the sensitivity conventions, the radiating piston and the characteristics fiche. - [Microphone Characterisation (IEC 60268-4)](/phonometry/devices/electroacoustics/microphones/): the sensitivity references, the directional patterns and the inherent noise. - [Swept-sine distortion and phase utilities](/phonometry/devices/electroacoustics/swept-sine-distortion/): harmonic separation from one exponential sweep, THD against excitation frequency, and minimum phase, group delay and excess phase. - [Audio-Frequency Induction Loops (IEC 60118-4)](/phonometry/devices/electroacoustics/induction-loops/): hearing loops for telecoil listeners: the 400 mA/m reference, the field of a loop by Biot-Savart, the loop as a load, the verdicts on a room, a refuge and a counter, the overload test, the amplifier and the neck loop. - [Headphones and Earphones (IEC 60268-7)](/phonometry/devices/electroacoustics/headphones/): the simulated programme signal of IEC 60268-1, the classification code, the rated impedance, the characteristic voltages and working levels, the protective device, the coupler, comparison and ear canal responses, and the probe microphone of Annex B. **[Broadcast](/phonometry/devices/broadcast/)** - [Programme loudness and true peak](/phonometry/devices/broadcast/program-loudness/): K-weighting and gated integrated loudness in LUFS, the momentary and short-term meters, the loudness range and the true-peak level. The sidebar files it inside Electroacoustics; it has its own section overview. - [Quasi-peak programme meter](/phonometry/devices/broadcast/quasi-peak/): the ITU-R BS.468-4 psophometric noise meter, whose clause 2 prints no time constant at all and specifies the detector through eleven tone-burst acceptance windows, the 0.775 V calibration that makes a reading dBqps, and three fitted time scales the windows pin only to within a factor of three. **[Noise control](/phonometry/devices/noise-control/)** - [Silencers](/phonometry/devices/noise-control/silencers/): reactive silencers by the four-pole transmission-matrix method and the reactive-versus-dissipative choice. - [Measuring a Silencer (ISO 7235 and ISO 11691)](/phonometry/devices/noise-control/silencer-measurement/): the substitution measurement a catalogue insertion loss comes from, its reverberation correction, and the reproducibility both standards publish. - [Enclosures and Cabins Measured (ISO 11546, ISO 11957)](/phonometry/devices/noise-control/enclosure-cabin-insulation/): the difference of two determinations that says what a built enclosure is worth, the annex that asks whether the room is good enough, and the cabin whose source-position count is read off its own answer. - [Silencers, Screens and Barriers In Situ](/phonometry/devices/noise-control/in-situ-noise-control/): three standards that measure a device where it already stands, and the three different corrections for background noise that must never be merged. - [Duct-Borne Noise: Fan to Room](/phonometry/devices/noise-control/duct-path/): the end-to-end fan-to-room calculation against a room criterion, and the higher-order-mode cut-on that limits every plane-wave method. - [HVAC Noise the German Way (VDI 2081)](/phonometry/devices/noise-control/vdi2081-air-systems/): the same chain by the German guideline, from the assembly-type fan model to the room step, against the worked sheet of its own Part 2. - [Control Valve Noise (IEC 60534-8-3)](/phonometry/devices/noise-control/control-valve-noise/): the five flow regimes of a throttling valve, the jet that sets the peak frequency, and the pipe wall that is what actually radiates. - [Hydrodynamic Valve Noise (IEC 60534-8-4)](/phonometry/devices/noise-control/valve-cavitation/): the same valve on a liquid line, where one threshold decides whether it cavitates and 0,1 in that threshold is worth 14 dB. - [Room to Room: Partition, Receiving Room, Criterion](/phonometry/devices/noise-control/room-to-room/): the source-room level through a partition into the receiving room, the noise criterion verdict and the transmission loss a partition or an enclosure needs. - [Industrial Noise Control: HVAC and Enclosures](/phonometry/devices/noise-control/noise-control/): duct attenuation and flow noise, and enclosure insertion loss. ## [Wave simulation](/phonometry/simulation/) Deterministic 2D finite-difference time-domain solvers, acoustic and elastic P-SV, validated against analytic oracles rather than a standard. It is the one area with no governing document, so its evidence is the closed-form solution it reproduces. - [2D FDTD wave simulation](/phonometry/simulation/fdtd-simulation/): a staggered pressure-velocity grid with Gaussian, tone and arbitrary-signal sources, rasterised obstacles, rigid, impedance and absorbing boundaries, and a frozen result carrying probe histories and field snapshots. - [Elastic waves and fluid-solid coupling](/phonometry/simulation/elastic-waves/): the P-SV companion solver on the same grid, with Rayleigh waves on free surfaces, mode conversion, Scholte interface waves and immersed-plate transmission.