Source: https://jmrplens.github.io/phonometry/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. Sixty-six guides sit in nine areas, and each area 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/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. ## [Core signal analysis](/phonometry/guides/sections/core-signal-analysis/) 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 Leq. Implements IEC 61260-1, ANSI S1.11, IEC 61672-1, ISO 7196, IEC 61252, ISO 1996-1, IEC 60942, ISO 18233 and the GUM. - [Build a sound level meter](/phonometry/guides/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/guides/sections/octave-filtering/)** - [Filter Banks](/phonometry/guides/filter-banks/): the five filter architectures, their frequency responses, band decomposition and zero-phase offline filtering. - [Block Processing](/phonometry/guides/block-processing/): stateful streaming analysis that carries filter state across buffers, for signals that never fit in memory. - [Multichannel and Performance](/phonometry/guides/multichannel/): vectorized analysis of many channels at once, with the (channels, samples) convention and performance notes. **[Levels and weighting](/phonometry/guides/sections/levels-weighting/)** - [Frequency Weighting (A, B, C, D, G, AU, Z)](/phonometry/guides/weighting/): the IEC 61672-1 ear-response curves, ISO 7196 G-weighting for infrasound and the historical B and D curves. - [Time Weighting](/phonometry/guides/time-weighting/): the Fast, Slow and Impulse exponential ballistics of IEC 61672-1. - [Integrated and Statistical Levels](/phonometry/guides/levels/): Leq and LAeq, the percentile levels L10/L50/L90, LCpeak and SEL, noise dose, Lden and the ISO 1996-1 rating levels. **[Signals and spectra](/phonometry/guides/sections/signals-spectra/)** - [Calibrated spectral analysis](/phonometry/guides/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/guides/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/guides/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/guides/cepstrum-echoes/): quefrency analysis, echo detection with the reflection coefficient read off the cepstral peak, liftering and the envelope spectrum. - [Time synchronous averaging](/phonometry/guides/synchronous-averaging/): extraction of a periodic waveform of known period, the comb filter that describes it and the choice of the number of averages. - [Correlation, time delay and envelope](/phonometry/guides/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/guides/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/guides/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/guides/sections/calibration-uncertainty/)** - [Calibration and dBFS](/phonometry/guides/calibration/): physical SPL calibration from a calibrator tone or a known sensitivity, and the digital full-scale mode. - [Measurement uncertainty (GUM and Monte Carlo)](/phonometry/guides/gum-uncertainty/): the law of propagation of uncertainty and the Monte Carlo method, with expanded uncertainty and coverage intervals. - [Data qualification](/phonometry/guides/data-qualification/): the reverse arrangement and runs tests for stationarity, and the Rice level-crossing and peak statistics with the irregularity factor. ## [Hearing and perception](/phonometry/guides/sections/hearing-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, ISO 7029, ISO 1999 and ISO 9612. **[Psychoacoustics](/phonometry/guides/sections/psychoacoustics/)** - [Loudness](/phonometry/guides/loudness/): loudness in sones by Zwicker, Moore-Glasberg, the time-varying ISO 532-3 model and the ECMA-418-2 Sottek Hearing Model, plus the ISO 226 equal-loudness contours. - [Sound Quality Metrics](/phonometry/guides/sound-quality/): sharpness in acum, and the ECMA-418-2 tonality, roughness and fluctuation strength. - [Prominent Discrete Tones (ECMA-418-1)](/phonometry/guides/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/guides/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/guides/psychoacoustic-annoyance/): the Fastl and Zwicker annoyance model built from loudness, sharpness, roughness and fluctuation strength. **[Speech](/phonometry/guides/sections/speech/)** - [Speech Transmission Index (STI)](/phonometry/guides/speech-transmission/): the modulation transfer function, the indirect method from an impulse response and the direct STIPA measurement. - [Speech Intelligibility Index](/phonometry/guides/speech-intelligibility/): the one-third-octave SII with its band-importance function, self-masking and upward spread of masking. - [Objective Intelligibility (STOI and ESTOI)](/phonometry/guides/objective-intelligibility/): the two correlation-based measures for time-frequency weighted noisy speech. **[Hearing and exposure](/phonometry/guides/sections/hearing-exposure/)** - [Hearing threshold (age and reference zero)](/phonometry/guides/hearing-threshold/): the age-related threshold distribution of ISO 7029 and the ISO 389-7 reference threshold of hearing. - [Noise-induced hearing loss (ISO 1999)](/phonometry/guides/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/guides/occupational-exposure/): the task-based, job-based and full-day strategies for LEX,8h, with the uncertainty budget and the upper limit. ## [Rooms and buildings](/phonometry/guides/sections/rooms-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 16283-1/-2/-3, ISO 10140, ISO 717-1/-2, EN 12354-1 to -6, ISO 12999-1, ISO 10052 and ANSI/ASA S12.2. **[Room acoustics](/phonometry/guides/sections/room-acoustics/)** - [Room Acoustics](/phonometry/guides/room-acoustics/): impulse-response acquisition and the room parameters EDT, T20, T30, C50, C80 and Ts, plus open-plan speech metrics and reverberation-room absorption. - [Image sources and the steady-state room field](/phonometry/guides/room-image-sources/): the deterministic image-source impulse response of a rectangular room, the room constant, critical distance and Schroeder frequency. - [Room-noise criteria (NC / RC Mark II)](/phonometry/guides/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/guides/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/guides/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/guides/sections/sound-insulation/)** - [Field Insulation Measurement and Ratings](/phonometry/guides/insulation-field/): airborne, impact and façade insulation in the field with their weighted single-number ratings, uncertainty and the survey method. - [Laboratory Insulation Measurement](/phonometry/guides/insulation-lab/): ISO 10140 element characterisation, insulation by intensity, floor-covering improvement on a mock-up and laboratory flanking transmission. - [Predicting Sound Insulation (EN 12354)](/phonometry/guides/insulation-prediction/): in-situ airborne and impact insulation from element data, with flanking paths, façade insulation and outdoor radiation. - [Predicting Panel Sound Insulation](/phonometry/guides/panel-sound-insulation/): the mass law and coincidence dip, double walls, slits and apertures, plate radiation efficiency and point mobilities. - [Dynamic stiffness of resilient materials (EN 29052-1)](/phonometry/guides/dynamic-stiffness/): the stiffness per unit area under a floating floor from the load-plate resonance, with the enclosed-gas term. ## [Materials and surfaces](/phonometry/guides/sections/materials-surfaces/) Absorption, airflow resistance, the impedance tube, porous models 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, ISO 10534-2, ISO 9053, ISO 17497-1/-2, ISO 13472 and EN 29052. - [Acoustic Materials](/phonometry/guides/materials/): the weighted absorption rating and its class, airflow resistance and resistivity, and the impedance-tube surface impedance, absorption and transmission loss. - [Porous and Multilayer Absorbers](/phonometry/guides/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. - [Surface Scattering, Diffusion and In-situ Absorption](/phonometry/guides/surface-scattering/): the random-incidence scattering coefficient, the autocorrelation diffusion coefficient, and in-situ road-surface absorption. ## [Vibration and structure-borne sound](/phonometry/guides/sections/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, ISO 10846, ISO/TS 7849, EN 15657, EN 12354-5, ISO 2631-1/-5, ISO 5349 and ISO 8041. **[Structure-borne sources](/phonometry/guides/sections/structure-borne/)** - [Mechanical mobility and the FRF family (ISO 7626-1)](/phonometry/guides/mechanical-mobility/): receptance, mobility and accelerance with their reciprocals, conversion between them, and the closed-form single-degree-of-freedom resonator. - [Bending-wave transmission at plate junctions](/phonometry/guides/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/guides/transfer-stiffness/): the dynamic transfer stiffness and loss factor of an isolator by the direct and indirect methods. - [Sound power from surface vibration (ISO/TS 7849)](/phonometry/guides/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. - [Structure-borne sound power of equipment (EN 15657)](/phonometry/guides/structure-borne-power/): the reception-plate method and the plate-independent source quantities, equivalent blocked force, free velocity and source mobility. - [Installed structure-borne sound (EN 12354-5)](/phonometry/guides/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. **[Human vibration](/phonometry/guides/sections/human-vibration/)** - [Human Vibration](/phonometry/guides/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/guides/multiple-shock-vibration/): the seat-to-spine transfer function, the acceleration dose, and the cumulative stress variable behind the lumbar injury probability. ## [Environment and transport](/phonometry/guides/sections/environment-transport/) Outdoor propagation, barriers, refraction, aircraft, rotorcraft and wind turbines. 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 1996-1/-2, ISO/PAS 1996-3, NT ACOU 112, ICAO Annex 16, IEC 61265, SAE ARP 5534, ECAC Doc 29/32 and IEC 61400-11. **[Outdoor sound](/phonometry/guides/sections/outdoor-sound/)** - [Outdoor Sound Propagation](/phonometry/guides/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/guides/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/guides/atmospheric-refraction/): effective sound-speed profiles, curved rays with a closed-form shadow-zone distance, and the GFPE relative-level field. - [Impulsive-sound prominence (NT ACOU 112)](/phonometry/guides/impulse-prominence/): the predicted prominence of each impulse from its onset rate and level difference, and the adjustment added to LAeq. **[Aircraft and wind energy](/phonometry/guides/sections/aircraft-wind/)** - [Aircraft noise: Effective Perceived Noise Level](/phonometry/guides/aircraft-noise/): perceived noisiness and PNL, the tone correction, the duration correction and the measurement-system verifier. - [Rotorcraft noise: the hemisphere method](/phonometry/guides/rotorcraft-noise/): the hemisphere source model with its propagation adjustments, flight-condition interpolation, and the single-event contours. - [Wind-turbine noise: sound power and tonal audibility](/phonometry/guides/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. ## [Underwater acoustics](/phonometry/guides/sections/underwater/) Levels referenced to 1 micropascal, ship radiated noise, pile driving, ambient noise and transmission 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/guides/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/guides/underwater-propagation/): spreading plus volume absorption, the speed of sound in sea water, the sonar equation, seabed reflection loss and the ambient-noise spectrum. ## [Sources and devices](/phonometry/guides/sections/sources-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 3744/3746, ISO 3745, ISO 9614-1/-2/-3, IEC 61043, ISO 4871, IEC 60268-3/-4/-5, ITU-R BS.1770-5 and EBU R 128. - [Sound Intensity (p-p)](/phonometry/guides/intensity/): two-microphone intensity with the field indicators that qualify the measurement. - [Sound Power](/phonometry/guides/sound-power/): the sound power level by five routes, enveloping surface, reverberation room, anechoic room and two grades of intensity scanning. - [Electroacoustics: distortion and frequency response](/phonometry/guides/electroacoustics/): harmonic and intermodulation distortion, THD+N and SINAD, dynamic range, the H1/H2 frequency-response estimators and the sensitivity conventions. - [Swept-sine distortion and phase utilities](/phonometry/guides/swept-sine-distortion/): harmonic separation from one exponential sweep, THD against excitation frequency, and minimum phase, group delay and excess phase. - [Industrial Noise Control: Silencers, HVAC and Enclosures](/phonometry/guides/noise-control/): reactive silencers by the transmission-matrix method, duct attenuation and flow noise, and enclosure insertion loss. - [Programme loudness and true peak](/phonometry/guides/program-loudness/): K-weighting and gated integrated loudness in LUFS, the momentary and short-term meters, the loudness range and the true-peak level. ## [Wave simulation](/phonometry/guides/sections/simulation/) A deterministic 2D finite-difference time-domain solver, 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/guides/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.