---
title: "Theory"
description: "Standards, math and design decisions behind phonometry."
---

The theory reference explains the standards, the mathematics and the design decisions behind every phonometry module. It is split into six domain pages, listed below with the sections each one hosts. Theory for the underwater modules lives with its guides: [Underwater Acoustics](/phonometry/guides/underwater-acoustics/) and [Underwater Propagation](/phonometry/guides/underwater-propagation/).

## [Signal Analysis](/phonometry/reference/theory/signal-analysis/)

- [Octave Band Frequencies (ANSI S1.11 / IEC 61260)](/phonometry/reference/theory/signal-analysis/#octave-band-frequencies-ansi-s111--iec-61260)
- [Frequency Resolution vs FFT Bin Spacing](/phonometry/reference/theory/signal-analysis/#frequency-resolution-vs-fft-bin-spacing)
- [Magnitude Responses |H(jw)|](/phonometry/reference/theory/signal-analysis/#magnitude-responses-hjw)
- [Filter Bank Design & Numerical Stability](/phonometry/reference/theory/signal-analysis/#filter-bank-design--numerical-stability)
- [Weighting Curves (IEC 61672-1)](/phonometry/reference/theory/signal-analysis/#weighting-curves-iec-61672-1)
- [Time Integration](/phonometry/reference/theory/signal-analysis/#time-integration)
- [G-weighting (ISO 7196)](/phonometry/reference/theory/signal-analysis/#g-weighting-iso-7196)
- [Event and dose metrics](/phonometry/reference/theory/signal-analysis/#event-and-dose-metrics)
- [Sound intensity (IEC 61043)](/phonometry/reference/theory/signal-analysis/#sound-intensity-iec-61043)
- [Measurement uncertainty (ISO/IEC Guide 98-3: GUM and Supplement 1)](/phonometry/reference/theory/signal-analysis/#measurement-uncertainty-isoiec-guide-98-3-gum-and-supplement-1)

## [Perception and Hearing](/phonometry/reference/theory/perception/)

- [Equal-loudness contours (ISO 226:2023)](/phonometry/reference/theory/perception/#equal-loudness-contours-iso-2262023)
- [Tone prominence: TNR and PR (ECMA-418-1)](/phonometry/reference/theory/perception/#tone-prominence-tnr-and-pr-ecma-418-1)
- [Zwicker loudness (ISO 532-1)](/phonometry/reference/theory/perception/#zwicker-loudness-iso-532-1)
- [Advanced loudness models & sound quality](/phonometry/reference/theory/perception/#advanced-loudness-models--sound-quality)
- [Modulation transfer and STI (IEC 60268-16)](/phonometry/reference/theory/perception/#modulation-transfer-and-sti-iec-60268-16)
- [Speech Intelligibility Index (ANSI S3.5)](/phonometry/reference/theory/perception/#speech-intelligibility-index-ansi-s35)
- [Hearing thresholds and presbycusis (ISO 389-7, ISO 7029)](/phonometry/reference/theory/perception/#hearing-thresholds-and-presbycusis-iso-389-7-iso-7029)
- [Noise-induced hearing loss (ISO 1999)](/phonometry/reference/theory/perception/#noise-induced-hearing-loss-iso-1999)

## [Rooms and Buildings](/phonometry/reference/theory/rooms-buildings/)

- [Room noise criteria (ANSI S12.2)](/phonometry/reference/theory/rooms-buildings/#room-noise-criteria-ansi-s122)
- [Room and building acoustics (ISO 18233, ISO 3382, ISO 16283, ISO 10140, EN 12354, ISO 12999, ISO 717, ISO 354)](/phonometry/reference/theory/rooms-buildings/#room-and-building-acoustics-iso-18233-iso-3382-iso-16283-iso-10140-en-12354-iso-12999-iso-717-iso-354)

## [Materials and Surfaces](/phonometry/reference/theory/materials-surfaces/)

- [Surface scattering and diffusion (ISO 17497-1, ISO 17497-2)](/phonometry/reference/theory/materials-surfaces/#surface-scattering-and-diffusion-iso-17497-1-iso-17497-2)
- [In-situ road surface absorption (ISO 13472-1, ISO 13472-2)](/phonometry/reference/theory/materials-surfaces/#in-situ-road-surface-absorption-iso-13472-1-iso-13472-2)
- [Acoustic material characterisation (ISO 11654, ISO 9053-1/2, ISO 10534-1/2, ASTM E2611)](/phonometry/reference/theory/materials-surfaces/#acoustic-material-characterisation-iso-11654-iso-9053-12-iso-10534-12-astm-e2611)

## [Environment and Transport](/phonometry/reference/theory/environment-transport/)

- [Environmental descriptors (ISO 1996-1)](/phonometry/reference/theory/environment-transport/#environmental-descriptors-iso-1996-1)
- [Impulsive-sound prominence (NT ACOU 112)](/phonometry/reference/theory/environment-transport/#impulsive-sound-prominence-nt-acou-112)
- [Outdoor propagation and occupational exposure (ISO 9613-1/2, ISO 9612)](/phonometry/reference/theory/environment-transport/#outdoor-propagation-and-occupational-exposure-iso-9613-12-iso-9612)
- [Sound power determination (ISO 3744/3745/3746, ISO 3741, ISO 9614-2/3)](/phonometry/reference/theory/environment-transport/#sound-power-determination-iso-374437453746-iso-3741-iso-9614-23)

## [Vibration](/phonometry/reference/theory/vibration/)

- [Human vibration (ISO 8041-1, ISO 2631-1/2, ISO 5349-1/2, Directive 2002/44/EC)](/phonometry/reference/theory/vibration/#human-vibration-iso-8041-1-iso-2631-12-iso-5349-12-directive-200244ec)
- [Multiple shocks (ISO 2631-5)](/phonometry/reference/theory/vibration/#multiple-shocks-iso-2631-5)
- [Point mobilities and radiation efficiency (Cremer 5, Hopkins 2.9)](/phonometry/reference/theory/vibration/#point-mobilities-and-radiation-efficiency-cremer-5-hopkins-29)
