Technical Standards Implemented in Audio Toolbox

R2026b

Audio Toolbox™ implements many technical standards and common industry metrics for speech, audio, and acoustics. The tables list each metric and the Audio Toolbox function, object, or block that implements the metric. For more information, see the feature reference pages.

Audio Measurement and Metering

Standard Designation	Title	Audio Toolbox Features	Description
ANSI S1.4:1983	American National Standard Specification for Sound Level Meters	splMeter	Specifies requirements for sound level meters. You can configure the splMeter System object™ to conform to standard-compliant specifications for frequency weighting, time weighting, and reported measurements such as Leq, Lmax, Lt, and Lpeak.
ANSI S1.11-2004	Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters	octaveFilter Octave Filter octaveFilterBank Octave Filter Bank octaveSpectrumEstimator graphicEQ Graphic EQ	Specifies requirements for octave-band and fractional-octave-band filters. You can configure the octaveFilter System object and octaveFilterBank System object to use standard compliant filters and use the isStandardCompliant object function to verify compliance. The graphicEQ System object uses center frequencies from the standard.
ANSI/ASA S1.42-2001	Design Response of Weighting Networks for Acoustical Measurement	weightingFilter Weighting Filter	Defines A-weighted and C-weighted frequency curves for acoustic measurements. The weightingFilter System object and Weighting Filter block implement these curves and can be configured to comply with the filter specifications from the standard.
EBU R 128	Loudness Normalisation and Permitted Maximum Level of Audio Signals	integratedLoudness loudnessMeter Loudness Meter	Defines loudness normalization and permitted maximum levels for audio signals, primarily for radio and television broadcasts in Europe. The integratedLoudness function, loudnessMeter System object, and Loudness Meter block implement algorithms from the standard for integrated loudness and loudness measurement.
IEC 60268-21:2018	Sound system equipment - Part 21: Acoustical (output-based) measurements	multitone	Defines acoustic output-based measurements for sound system equipment, including multitone test signals. The multitone function fully implements the multitone signal requirements from the standard.
IEC 61672-1	Electroacoustics - Sound level meters - Part 1: Specifications	splMeter	Specifies performance requirements for sound level meters as an international standard. You can configure the splMeter System object to conform to standard-compliant specifications for frequency weighting, time weighting, and reported measurements such as Leq, Lmax, Lt, and Lpeak.
IEC TR 60268-18:1995	Sound system equipment - Part 18: Peak programme level meters - Digital audio peak level meter	audioLevelMeter	Specifies requirements for digital audio peak level meters. The audioLevelMeter System object implements peak measurement and decay rate specifications from the standard.
ITU-R BS.1770-4	Algorithms to measure audio programme loudness and true-peak audio level	weightingFilter Weighting Filter audioLevelMeter	Defines algorithms for measuring audio program loudness and true-peak level. You can configure the weightingFilter System object to use the K-weighting filter from the standard and the audioLevelMeter System object to use the true-peak measurement method from the standard.

Psychoacoustic Metrics

Standard Designation	Title	Audio Toolbox Features	Description
DIN 45692:2009	Measurement technique for the simulation of the auditory sensation of sharpness	acousticSharpness	Defines measurement of auditory sharpness. The acousticSharpness function implements the algorithm from the standard, using ISO 532-1 loudness calculations internally.
ECMA-418-1	Psychoacoustic metrics for ITT equipment — Part 1 (prominent discrete tones)	acousticToneToNoiseRatio acousticProminenceRatio	Defines methods for detecting and quantifying prominent discrete tones in sound. The acousticToneToNoiseRatio and acousticProminenceRatio functions implement the tone detection and prominence determination algorithms from the standard.
IEC 60318-4:2010	Electroacoustics — Simulators of human head and ear — Part 4: Occluded-ear simulator	Ear Canal with Ear Drum Ear Drum Impedance	Specifies an occluded-ear simulator for electroacoustic measurements. The Ear Canal with Ear Drum and Ear Drum Impedance Simscape™ blocks model acoustic impedances based on the standard.
ISO 532-1:2017	Acoustics — Methods for calculating loudness — Part 1: Zwicker method	acousticLoudness phon2sone sone2phon	Defines the Zwicker method for calculating loudness of stationary and time-varying sounds. You can configure the acousticLoudness function to use the Zwicker method and phon2sone/sone2phon to convert between loudness units as defined in the standard.
ISO 532-2:2017	Acoustics — Methods for calculating loudness — Part 2: Moore-Glasberg method	acousticLoudness phon2sone sone2phon	Defines the Moore-Glasberg method for calculating loudness of stationary sounds. You can configure the acousticLoudness function to use the Moore-Glasberg method and phon2sone/sone2phon to convert between loudness units as defined in the standard.
—	Zwicker method for acoustic fluctuation and roughness	acousticFluctuation acousticRoughness	The Zwicker fluctuation strength and roughness models quantify temporal modulation perception. The acousticFluctuation and acousticRoughness functions implement these models using ISO 532-1 loudness calculations internally.

Room Acoustics and Spatial Audio

Standard Designation	Title	Audio Toolbox Features	Description
AES69-2022	AES standard for file exchange — Spatial acoustic data file format (SOFA)	sofaconvention sofaread sofawrite interpolateHRTF	Defines the SOFA file format for exchanging spatial audio data such as head-related transfer functions (HRTFs) and impulse responses. The sofaread and sofawrite functions provide file input and output, the sofaconvention function creates objects that store SOFA data in one of the defined conventions, and the interpolateHRTF function interpolates HRTF data stored in a SOFA convention.
ANSI/ASA S12.2-2019 (R2023)	Criteria for Evaluating Room Noise	noiseCriteria roomNoiseCriteria roomCriteria noiseCriteriaCurves noiseCriteriaRecommendations	Defines criteria for evaluating room background noise using noise criteria (NC), room noise criteria (RNC), and room criteria (RC) Mark II methods. The noiseCriteria, roomNoiseCriteria, and roomCriteria functions implement these evaluation methods, while noiseCriteriaCurves and noiseCriteriaRecommendations return the reference curves and recommended levels for different room types from the standard.
ISO 3382-1:2009 / ISO 3382-2:2008	Acoustics — Measurement of room acoustic parameters	rt60	Defines measurement of room acoustic parameters for performance spaces and ordinary rooms. The rt60 function implements procedures from the standard for computing reverberation time, clarity (C50, C80), definition (D50), and center time (Ts).

Speech Quality and Intelligibility

Standard Designation	Title	Audio Toolbox Features	Description
ANSI/ASA S12.65-2006 (R2020)	American National Standard for Rating Noise with Respect to Speech Interference	speechInterferenceLevel	Defines methods for quantifying the potential of noise to interfere with speech. The speechInterferenceLevel function implements the speech interference level (SIL) metric as defined in the standard.
ASA/ANSI S3.5-1997 (R2024)	Methods for Calculation of the Speech Intelligibility Index	speechIntelligibilityIndex siiExcitation	Defines the calculation of the speech intelligibility index (SII). The speechIntelligibilityIndex function implements all methods for SII calculation defined in the standard, and siiExcitation generates the test signals defined in the standard for measuring SII in a physical system.
IEC 60268-16:2020	Sound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index	speechTransmissionIndex stipaExcitation	Defines the calculation of the speech transmission index (STI). The speechTransmissionIndex function implements all methods for STI calculation defined in the standard, and stipaExcitation generates the test signals defined in the standard for measuring STI in a physical system.
ITU-T G.100.1	The use of the decibel and of relative levels in speechband telecommunications	dBov	Defines logarithmic power level measurements used in telecommunication systems. The dBov function implements algorithms from the standard for computing the average and peak signal levels of a signal relative to the point of digital overload.
ITU-T P.810	Modulated noise reference unit (MNRU)	mnru	Defines the modulated noise reference unit (MNRU) for subjective speech quality testing. The mnru function implements algorithms in the standard for adding modulated noise to a speech signal.
—	STOI (Short-Time Objective Intelligibility)	stoi	STOI is a widely used algorithm for predicting speech intelligibility in noisy conditions. The stoi function computes the metric by comparing a processed speech signal against a reference signal.
—	ViSQOL (Virtual Speech Quality Objective Listener)	visqol	ViSQOL is an open-source algorithm for predicting perceived audio quality. The visqol function implements ViSQOL v3 by comparing a degraded audio signal against a reference signal.