Title

Electroacoustics

Scope

Standardization of electroacoustic instruments and systems for acoustic and audiometric measurements. This includes performance requirements, and calibration and test methods for:

acoustic measurement systems including; microphones, sound calibrators, sound level meters, filters, and equipment used for measurement of aircraft noise, audiometric measurement systems and related instruments and equipment, including; audiometric equipment and transducers (earphones and bone vibrators), ear simulators, hearing aids and induction loop systems.

Excluded are: 
a) standards for equipment in the field of audio and audio- visual engineering and recording as dealt with by TC 100; 
b) standards and terminology for ultrasonic techniques dealt with by TC 87.
NOTE - Close co-operation is, however, maintained with TC 87 in the fields of common interest.

MT 4: Sound level meters

WG 5: Measurement microphones

WG 10: Audiometric equipment

WG 13: Hearing aids

MT 17: Sound calibrators

WG 21: Head and ear simulators

WG 22: Hearing loop systems and equipment

MT 23: Revision of IEC 61265, Instruments for aircraft noise certification

AHG 26: Alignment of standards for measurement microphones, sound level meters and sound calibrators

AG 27: Chair Advisory Group

JWG 29: Determination of high frequency sound pressure levels emitted by high intensity ultrasonic equipment (joint with ISO/TC 43/SC 1/JWG 1)

TC 29's technical work plays a vital role in underpinning large areas of social, environmental, medical diagnostic and rehabilitation applications, where the accurate production and/or measurement of sound is needed. Electroacoustical instrumentation and devices are therefore required by a very diverse range of users.

The declaration and verification of noise emission values for all kinds of machinery, consumer and domestic products, as presently required by many national or regional regulations, presupposes the use of uniformly specified and sophisticated sound measuring instrumentation with well-defined tolerances.

Telephone retailing, banking and information provision creates a demand for the use and development of TC 29 standards in determining the acoustic environment in which these businesses operate, and in particular the noise to which operators are exposed in the course of their work.

For the control of noise immission there is a growing need for instrumentation for the measurement and analysis of noise exposure in the workplace as well as in residential areas, and within the music and entertainment sectors. The available instruments and measuring methods still represent a high degree of simplification compared to the human perception of noise and to the effect on our hearing. However, current instrumentation provides a consistent means of measurement, which allows preventative action to be taken where appropriate based on the best available data.

Regulation and law on acoustical instrumentation differs widely from country to country. For example, in some countries pattern evaluation of new models of instrument against the international standard is required before the device can be sold, and regular testing of individual specimens is also required by law. In other countries this is not the case and it is up to the user to follow good measurement practice. Hence the aim of TC 29 is also to encourage testing in countries where it is not mandated by use of the same agreed international specified test methods within all countries, ensuring consistency and cost-effective testing across world markets.

In terms of worldwide market this varies considerably for the different instruments within the scope of the Committee’s remit, and as the number of key manufacturers in some areas is quite small, data on sales is often not available for commercial reasons. However, as examples some 8 million hearing aids are manufactured worldwide each year, and it is known that in some countries lost productivity due to noise can equate to up to approximately 2% of GDP.

Programmes supporting innovation and research already acknowledge the widespread benefits of standardization, and are increasingly supportive of pre-normative research. The European Metrology Partnership is once such programme, that makes regular calls to CEN and CENELEC (and the equivalent international bodies including IEC) for new research priorities and potential topics. TC 29 is representing stakeholders by engaging with the programme and suggesting topics for pre-normative research in the field of electroacoustics. 

The demand for electroacoustic devices and measurement is worldwide, with many applications and stakeholders, and in many countries the control and measurement of noise is covered by law or legislative directives.

The range of users of the standards will include governments, local authorities, planners, the medical profession, health and safety professionals and agencies, environmental noise consultants and agencies, manufacturers of instrumentation and equipment, as well as the many laboratories and test houses around the world.

Users of TC 29 standards include international and national standards organizations, and in many countries the international standards are directly adopted with no change as equivalent national standards, with the number of adopting countries increasing.

As an example, noise is the second largest form of environmental pollution (after air quality) and has been identified by the World Health Organisation as the second largest health risk in Western Europe. Up to 170 million citizens in the EU alone are said to be living in areas where the noise levels were such as to cause serious annoyance during daytime. Also, reports from some countries found that some 30% of the population are highly disturbed by road traffic noise. Noise annoyance has proven negative impacts on health including cardio-vascular disease, effects of metabolism leading to diabetes, and detriments to mental health. It also interfers with sleep and cognitive development wit profound consequences. Measures to be taken to reduce the noise are normally very expensive and must be based on proven facts. Similarly, ability to make reliable measurement of aircraft noise is vital to the aircraft and airline industries, airport operators and regulators, central government and the general population.

Noise induced hearing impairment is one of the most prevalent occupational hazards leading to one of the most globally widespread disabilities and financial consequences for social care. Equipment for the measurement and analysis of noise as covered by TC 29, is in high demand and allows reliable data to be gathered based on accurate and reproducible measurements. Worldwide research in psychoacoustics is aiming at a better understanding of human reactions to noise exposure that certainly will call for further development of measuring techniques and instrumentation. Hearing assessment is now carried out routinely at all stages of life from birth to old age. High quality data yielded by well-specified audiometric equipment can lead to early detection and greater success in reducing further risk or in remedial treatment with hearing aids.

Hearing aid performance, specification and measurement is the subject of a series of standards produced by TC 29. The associated standardization of ear simulators and head and torso simulators for measuring performance has allowed a better understanding to be found of the relationship between subjective and objective measurements. The effect of these standards and the standards for induction loop systems, has been to improve the means by which the vast majority of hard of hearing people communicate, and so improve their quality of life. The importance of these standards is only growing as unregulated direct-to-consumer assistive hearing devices are now available. 

The ability to accurately measure the threshold of hearing is crucial to hearing conservation programmes, the early detection of hearing loss in children and the diagnosis of hearing loss. TC 29 works in conjunction with ISO/TC 43 to ensure that standards for thresholds of hearing and other techniques for audiometry are integrated. The same close cooperation also takes place on the integration of measurement methods and the necessary instrumentation for determination of acoustic power emission from machinery, total noise exposure of workers during a workday, etc.

Technology trends

Rapid development in digital measurement, wireless technologies such as Wi-Fi and Bluetooth, manufacturing techniques, miniaturisation and wearable technologies, offer increased capabilities and more sophistication in general sound measuring instrumentation, and in audiometry and hearing aids. As measurement data increasingly exists only in digital form, compatible approaches to calibration and performance verification will need to be implemented. The advent of automated methods of testing and calibration also have a key role to play, and newer digital designs may mean that in practice reduced test procedures are possible without detriment to quality assurance. Testing of software running within instruments and devices, is something that TC 29 may need to address. Hence the international standards require continuous revision and updating to ensure specifications and test procedures remain appropriate and fit-for-purpose. 

New technologies are continually evolving, for example latest Bluetooth technologies are driving new standardisation developments for hearing aids. Direct-to-consumer devices and the re-purposing of personal earphones is already a reality. For noise measurement the increasing interest in MEMS microphone-base measurement systems creates a set of new considerations for conformance testing with the need becoming more urgent. A general trend towards the use of smaller microphones creates a demand for appropriate methods of calibration. For ear simulators, new characterisations of the human ear, either by measurement or numerical modelling capabilities, can be adopted into new ear simulator specifications. There are emerging new applications for ear simulators to, e.g. for evaluating body-conduction transmission into the occluded ear canal when earphones or hearing aids are worn, and electromagnetic human-equivalent version of the pinna specification. In audiometry, hearing tests may also need to evolve to consider assessment of hearing effort. The Committee needs to ensure that as these technologies start to become mainstream, standardisation keeps pace with introduction of new products and systems, and their usage. 

Users sometimes take a modular approach to configuring measurement systems that requires additional considerations for specifying and testing performance. These are often multi-channel and computer based. Development of associated standards for measurement systems is required to ensure that fit-for-purpose specifications and appropriate testing regimes are provided for these systems. 

Acoustic sensors have become ubiquitous as components in consumer products, pervading into all walks of life. The market penetration brings a new level of affordability for acoustic sensor technologies, which can open the way for novel applications for acoustic measurement, such as the roadside noise cameras being trialled in several nations, and distributed noise measurement systems. New applications such as these often deploy microphones as an array or network of several sensors and thus set new challenges to validate the performance of the measurement equipment. 

The world is currently experiencing the artificial intelligence (AI) and machine learning (ML) revolution, and it is a foregone conclusion that electroacoustic instrumentation will feature such capabilities in the future. The purpose of noise measurement is often to estimate the human perceived response, but this is extremely subjective (a function of context, state of mind, individual attitudes, time of day etc.). AI perhaps offers the best potential there has ever been for relating physical measurements to subjective response. In audiometry, instruments used for otoacoustic emission and auditory evoke response rely to an extent on human interpretation of the results produced. However, the use of AI to make the assessment more ‘objective’ or at least automatic is already under consideration. Such features would inevitably be integrated into instrumentation. Hearing aids already deploy sophisticated signal processing and AI has a clear role here to in mimic a normal-hearing person’s ability to discriminate speech from other elements of the stimulus. 

Market trends

Market trends are broadly in line with the technology trends mentioned above, which are often enabling greater flexibility, more customisation and enhanced functionality of devices, whilst maintaining a static cost base. Similarly, miniaturisation in hearing aids and other areas has progressed considerably over recent years, and although some further change may occur the usability of devices will continue to be a key factor. The growth in direct-to-consumer hearing aids will somehow require considerations for quality assurance and safety when the usual testing and fitting regime is bypassed. 

A growth in sources of low frequency noise and infrasound (especially associated with renewable energy generation) is driving a need for new instrumentation specifications to ensure measurement systems used for environmental noise assessment in these applications, are fit-for-purpose. If current test and calibration protocols are mirrored for low frequency sound, there is a particular market need for a portable sound calibrator operating in this frequency range, and corresponding coverage in TC 29 standards. At the other frequency extreme, sources of airborne ultrasound in industry and in society are proliferating. The need to assess and control exposure creates new demands for suitable measurement instrumentation, and methods of hazard assessment. 

In 2015 the United Nations established their 2030 Agenda for Sustainable Development comprising 17 Strategic Development Goals (SDGs) covering such global challenges as the eradication of poverty and hunger, climate change, health, education and economic growth. TC 29 has the potential to contribute to many of these goals (see Annex B), that would see the emergence of new markets and new requirements for standardisation on electroacoustic. For example, WHO is endorsing the use of mobile hearing screening solutions.

TC 29 has liaisons with relevant TCs. As new markets and applications emerge, the range of other TCs with which TC 29 has liaison should be kept under review, so that TC 29 remains the central point of responsibility for any specification and performance aspects of electroacoustic devices and systems.

TC 29 will actively continue to promote the ongoing liaisons to other committees and to system committees and to seek new liaisons, where relevant.

* in particular, IEC/TC 100/TA 16 “Active Assisted Living (AAL), wearable electronic devices and technologies, accessibility and user interfaces“, and IEC/TC 100/TA 20 "Analogue and digital audio".

Cooperation established:

• Through liaison with the following international organizations:
  • ITU-T "International Telecommunication Union – Telecommunication Standardization Sector"
  • ICAO "International Civil Aviation Organization"
  • Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV)
• Through experts working on other TCs or with other bodies e.g. ISO/TC 43 and ICAO
• New liaisons to be sought:

  • IEC/TC 88 "Wind energy generation systems"

    NOTE - Formal action for liaison to wait until ICAO wants to include information on the ground plane microphone in a TC 29 standard

  • European Telecommunications Standards Institue (ETSI)

TC 29 standards include where necessary, performance specifications, reproducible test requirements and test methods.

With regard to uncertainties and conformance assessment TC 29 has prepared a basic document on policy on measurement uncertainty and conformance assessment for use in documents prepared by IEC/TC 29, Electroacoustics, given in doc. 29/810/INF.