NOTICE. (Formulated under the cognizance of the CTA R6 Portable, Handheld and In-Vehicle Electronics Committee.)

Transcription

1 ANSI/CTA Standard Personal Sound Amplification Performance Criteria ANSI/CTA-2051 January 2017

2 NOTICE Consumer Technology Association (CTA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any member or nonmember of the Consumer Technology Association from manufacturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than Consumer Technology Association members, whether the standard is to be used either domestically or internationally. Standards, Bulletins and other technical publications are adopted by the Consumer Technology Association in accordance with the American National Standards Institute (ANSI) patent policy. By such action, the Consumer Technology Association does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard, Bulletin or other technical publication. This document does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this document to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. This document is copyrighted by the Consumer Technology Association (CTA) and may not be reproduced, in whole or part, without written permission. Federal copyright law prohibits unauthorized reproduction of this document by any means. Organizations may obtain permission to reproduce a limited number of copies by entering into a license agreement. Requests to reproduce text, data, charts, figures or other material should be made to the Consumer Technology Association (CTA). (Formulated under the cognizance of the CTA R6 Portable, Handheld and In-Vehicle Electronics Committee.) Published by CONSUMER TECHNOLOGY ASSOCIATION 2017 Technology & Standards Department All rights reserved

3 FOREWORD This standard was developed by the Consumer Technology Association s R6 Portable Handheld and In-Vehicle Electronics Committee. i

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5 CONTENTS 1 Scope Normative References Normative Reference List Normative Reference Acquisition Informative References Informative Reference List Informative Reference Acquisition Compliance Notation Definitions Symbols and Abbreviations Criteria for Standardization Frequency Response Bandwidth (Category 1) Frequency Response Smoothness (Category 1) Maximum Acoustic Output (Category 1) Distortion Control Limits (Category 1) Output Distortion Input Distortion Self-generated Noise Levels (Category 1) High Frequency Gain Provided (Category 2) Battery Life (Category 2) Latency (Category 2) RF-Immunity (Category 2) Fixed or Level Dependent Frequency Equalization - Tone Control (Category 3) Level Dependent Gain/Compression (Category 3) SNR Enhancement (Category 3) Noise Reduction (Category 3) Feedback Control / Cancellation (Category 3) Personalization (Category 3) General Specification and Reporting Device Coupling to the Ear (Category 3) Wireless Connectivity (Category 3) Annex A: Maximum Acoustic Output iii

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7 Personal Sound Amplification Performance Criteria 1 Scope This standard includes technical performance metrics and associated target values for consumer products that provide personal sound amplification and/or enhancement to a user. Products shall meet the stated requirements to be considered as compliant to this standard. Personal sound amplification may be a single function within a larger set of device capabilities. Descriptions of feature specific device performance baselines and metrics of measurement are described. Device performance capabilities have been divided into feature specific sub-sections that identify: required minimum performance values, metrics of measurement necessary to identify feature specific performance values, and methods of reporting prescribed to each feature specific value. 2 Normative References The following standards contain provisions that, through reference in this text, constitute normative provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed here Normative Reference List 1. ANSI S , Specification of hearing aid characteristics 2. IEC , Electroacoustics Hearing aids Part 0: Measurement of the performance characteristics of hearing aids 3. IEC , Electroacoustics Hearing aids Part 7: Measurement of the performance characteristics of hearing aids for quality inspection for delivery Normative Reference Acquisition 1. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 2. International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , 3. International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , Informative References The following references contain provisions that, through reference in this text, constitute informative provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below Informative Reference List 1. ANSI/S , Acoustical terminology 2. ANSI/S , Method for measuring the intelligibility of speech over communication systems 3. ANSI/S , Occluded Ear Simulator 4. ANSI/S (R2008), Bioacoustical terminology 5. ANSI/S , Method of measurement of performance characteristics of hearing aids under simulated real-ear working conditions 6. ANSI/S3.42-Part1-1992(R2012), Part 1: Testing hearing aids with broad-band noise signal 1

8 7. ANSI/S3.42-Part2-2012, Part 2: Method of characterizing signal processing in hearing aids with speech-like signal 8. ANSI/S , Method of measurement of real-ear performance characteristics of hearing aids 9. ANSI/S , Specification of performance measurements of hearing assistive devices and systems 10. ANSI/C , Compatibility between hearing aids and cellular telephones 11. IEC A12:2011, Audio video and similar electronic apparatus: safety 12. IEC , Sound system equipment: Headphones and earphones associated with personal music players maximum SPL measurement method Part 1: General method for one package equipment 13. IEC , Electroacoustics Hearing aids Part 8: Methods of measurement of performance characteristics of hearing aids under simulated in-situ working conditions 14. IEC , Electroacoustics Hearing aids Part 13: Electromagnetic compatibility (EMC) 15. IEC , Electroacoustics Hearing aids Part 14: Specification of a digital interface device 16. IEC , Electroacoustics Hearing aids Part 15: Methods for characterizing signal processing in hearing aids with a speech-like signal 17. IEC , Electroacoustics Simulators of human head and ear Part 4: Occluded-ear simulator for the measurement of earphones coupled to the ear by means of ear inserts 18. IEC , Medical electrical equipment - Part 2-66: Particular requirements for the basic safety and essential performance of hearing instruments and hearing instrument systems 19. IEC , Electroacoustics - Equipment for the measurement of real-ear acoustical characteristics of hearing aids 20. ISO , Acoustics Procedures for the measurement of real-ear acoustical characteristics of hearing aids 21. ISO , Acoustics Determination of sound emission from sound sources placed close to the ear - Part 1: Technique using a microphone in the real ear (MIRE technique) 22. ISO , Acoustics - Determination of sound emission from sound sources placed close to the ear - Part 2: Technique using a manikin 23. Killion MC and Monser EL (1980) CORFIG: Coupler response for flat insertion gain, Chapter 8 in Acoustical Factors Affecting Hearing Aid Performance, Studebaker GA and Hochberg I, eds. (University Park Press, Baltimore). 24. Killion MC and Revit LJ (1993) CORFIG and GIFROC: Real Ear to Coupler and Back, Chapter 5 in Acoustical Factors Affecting Hearing Aid Performance (2nd ed.), Studebaker GA and Hochberg I, eds. (Allyn and Bacon, Toronto), p Killion MC, Berger EH and Nuss RA (1987) Diffuse field response of the ear. J. Acoust. Soc. Am. Suppl.1 vol 81, S IEEE , IEEE Standard Methods for Measuring Transmission Performance of Analog and Digital Telephone Sets, Handsets, and Headsets Informative Reference Acquisition 1. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 2. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 3. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 4. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 5. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 6. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 2

9 7. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 8. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , 9. Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , IEEE, 445 Hoes Lane Piscataway, NJ 08854, International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Electrotechnical Commission, 3, rue de Varembé P.O. Box 131 CH Geneva 20 Switzerland, , International Organization for Standardization, Chemin de Blandonnet 8 CP Vernier, Geneva Switzerland, , International Organization for Standardization, Chemin de Blandonnet 8 CP Vernier, Geneva Switzerland, , International Organization for Standardization, Chemin de Blandonnet 8 CP Vernier, Geneva Switzerland, , International Organization for Standardization, Chemin de Blandonnet 8 CP Vernier, Geneva Switzerland, , Acoustical Society of America, 1305 Walt Whitman Road, Suite 300 Melville, NY 11747, , IEEE, 501 Hoes Lane, Piscataway, NJ, 08854, Compliance Notation As used in this document shall and must denote mandatory provisions of the standard. Should denotes a provision that is recommended but not mandatory. May denotes a feature whose presence does not preclude compliance, and implementation of which is optional. Optional denotes items that may or may not be present in a compliant device. 3 Definitions Acoustical Coupler An acoustical Coupler is a cavity of specified shape and volume used for the calibration of earphones or microphones in conjunction with a calibrated microphone adapted to measure the sound pressure developed in the cavity. NOTE Acoustical couplers are specified in ANSI/ASA S /Part 1/IEC :2009, ANSI/ASA S /Part 3/IEC :2014, and ANSI/ASA S /Part 5/IEC :

10 Automatic Gain Control CORFIG Compression Automatic Gain Control is a means (other than peak clipping) by which the gain is automatically controlled as a function of the level of the signal being amplified. CORFIG denotes Coupler Response for Flat Insertion Gain. The CORFIG tables (Table 4.1A, B and C) are corrections used with laboratory measurements of hearing devices to enable estimation of the expected "real ear" response a wearer will receive. Compression is a means by which the amount of amplification (gain) decreases automatically as the signal level increases. dba dba refers to sound pressure level that is filtered by an A- weighting filter prior to computing the overall level. The A weighting approximately accounts for the frequency dependence of relative loudness perceived by the human ear. Insertion Gain Insertion Gain is the difference (in db) between the sound pressure level measured with the device in situ and that obtained in the open ear. NOTE: Insertion gain may be measured with a probe microphone on a human listener or using a manikin equipped with an ear simulator. Insertion Response Insertion Response is the Insertion Gain versus frequency. Linear Amplification Limiting Manikin (head and torso simulator) Multiband Equalization Multiband Signal Processing A change in input results in the same relative change in output; in particular there is no change in gain with change in input level. Signal processing to keep the output level from exceeding a threshold (i.e., limit), typically achieved by quickly reducing the gain applied to high-level input signals. A head and torso simulator extending downward from the top of the head to the waist and designed to simulate the sound pick-up characteristics and acoustic diffraction produced by a median adult human head and torso. Frequency shaping achieved by separate adjustment of the gain in more than one band. The resulting frequency response may be independent of level (simple equalization) or may change with level (level dependent frequency response). The latter is typically used for those desiring increased gain for soft high frequency sounds but do not wish loud low frequency sounds to be amplified. The frequency bandwidth of the device is divided into more than one band, enabling individual control of the processing in each band. Example use cases are compression, equalization, noise rejection, and feedback rejection. 4

11 Occluded Ear Simulator Real Ear Coupler Difference Single Band Signal Processing A device used for testing which approximates the acoustic transfer impedance of the inner part of the human ear canal, from the tip acoustic output of an ear mold insert device to the eardrum. In the case of hearing devices that do not insert into the ear canal, e.g. earphones that are designed to lay in the concha or be laced over the ear, a Head and Torso Simulator, as defined in ANSI S3.36 is appropriate for testing. Denotes the difference between (a) the response of an in-situ device measured at the eardrum and (b) the same device measured in a coupler. Average values of these differences are shown in Table 4.1C. Signal processing (e.g., compression) applied by treating the entire frequency bandwidth of the device as a single channel. THD+N Wide Dynamic Range Compression Denotes Total Harmonic Distortion plus Noise. It represents (a) the sum of the powers of all harmonic distortion components plus noise divided by (b) the power of the fundamental (test) signal frequency. The square root of this ratio is expressed in percent. Non-linear processing that is differentially applied to sounds as a function of their level. It is typically done so as to amplify soft sounds more so than loud sounds, thereby reducing the dynamic range. NOTE: Wide Dynamic Range Compression and Limiting are similar in process but different in degree and perceived effect. 3.1 Symbols and Abbreviations AGC CORFIG db dba OSPL RECD SNR SPL THD Automatic Gain Control Coupler Response for Flat Insertion Gain Decibel A-weighted Decibels Output Sound Pressure Level Real Ear Coupler Difference Signal to Noise Ratio Sound Pressure Level Total Harmonic Distortion 4 Criteria for Standardization Three categories of standardization level are defined and described below. These categories identify three levels of technical performance specification differentiated by a decrease in the degree of standardized specification required for fulfilment of the feature requirements. The level of performance specification recommended by this document for each feature is independently identified for each feature within the associated sub-section. Measurement methods for evaluation of all relevant metrics characterized in the feature specific sub-sections are identified and described when appropriate. Category 1: The description of a hearing device performance parameter which must include the value measured per the specified testing method. Category 1 requirements include a threshold or acceptable 5

12 range for the parameter measured. Category 2: The description of a hearing device performance parameter which must include the value measured per the specified testing method. Category 2 requirements do not include a threshold or acceptable range for the parameter measured. Category 3: Presence of the technological capability or feature shall be reported in the device description. The specific value/metric for measurement of this value is not within the scope of the standard. Measurements in this standard specify the use of tones (sine waves) as a stimulus signal. It is recognized that many devices will include non-linear audio processing (DSP) (for example, noise suppression, band equalization) that may cause unexpected test results when tones are used as test stimulus signals. Therefore, when performing measurements using tones as specified in Section 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, and 4.7, any non-linear signal processing should be disabled. Alternatively, if using tones is not appropriate for testing a specific device, for example, due to the inability to disable non-linear processing, alternative test signals such as real speech and 1/3 rd octave pulsed noise signals may be used. If an alternate test signal is used, 1/3 rd octave analysis should be performed to obtain individual frequency based test results, similar to what would have been obtained if tone-based measurements were performed. As in ANSI S , Section 5.2.5, controls of the device under test shall be set for the widest available frequency response range, e.g., tone control typically set for minimum effect. As in ANSI S , Section 4.1, test signal(s) shall exceed background noise by at least 10 db, and unwanted stimuli shall be sufficiently low so as not to affect the test results by more than 1 db. In addition to the tests included in this standard, it is recommended that informal listening tests be performed during both product development and final evaluation to ensure that there are no undesirable effects present that are not revealed by objective testing. Category Frequency Response Bandwidth (Category 1) Frequency Response Bandwidth of a sound reproduction system relates to the portion of the input acoustic spectrum that the device can provide to a user. A consistent methodology for measurement (relative to a common reference) and assessment of the spectrum width provides the consumer a means to compare and evaluate competing systems. The upper and lower cut off frequencies are defined as the frequencies at which the estimated insertion response falls 10 db relative to the average level of the insertion gain in the one-third octave bands from 500 to 3150 Hz. The low frequency cut off for all devices shall extend to 250 Hz or below. Devices labeled as Standard Band shall have an upper cut off frequency of 5 khz or greater. Devices labeled as Wide Band shall have an upper cut off frequency of 10 khz or greater. Frequency response bandwidth shall be reported and labeled on the packaging. Method: Frequency response is measured in a coupler according to ANSI S using an 80 db SPL input signal. The one-third-octave insertion gain response shall be calculated from the values of the pressure response measured in a 2cc coupler or an occluded ear-simulator coupler (as specified in IEC , commonly called a "711" coupler). 6

13 To obtain the one-third-octave insertion response, the appropriate CORFIG corrections needed to obtain insertion gain are used in each case. These CORFIG corrections are shown in Tables 4.1A and 4.1B for the 2cc coupler and the occluded ear-simulator coupler, respectively. When bandwidths above 8 khz are to be verified the occluded ear simulator coupler must be used. The components underlying the overall CORFIGs are given in Table 4.1C. For example, it shows that the choice of microphone location generally results in a small correction. The corrections provided are applicable for hearing devices with microphone positions that are typical for in the ear (ITE) and behind the ear (BTE) device configurations. If a hearing device with a microphone position other than described above is to be tested, then an appropriate correction to a diffuse field simulation may be needed to account for the device s microphone position in addition to the corrections for the ear simulator coupling. Table 4.1A: CORFIG corrections for converting 2cc coupler response to estimated insertion gain assuming diffuse-field measurement. Values are given for device microphone locations that are in the ear (ITE) and behind the ear (BTE) at one-third octave center frequencies (Freq). Freq ITE CORFIG (2cc) BTE CORFIG (2cc) Hz db db

14 Table 4.1B: CORFIG corrections for converting Occluded Ear Simulator response to estimated insertion gain including corrections to simulate a diffuse-field measurement. Freq ITE CORFIG (Ear Simulator) BTE CORFIG (Ear Simulator) Hz db db

15 Table 4.1C: Details underlying the set of CORFIG diffuse field corrections used in Tables 4.1A and 4.1B. CORFIG formulae based on microphone location (A1 and A2), acoustic coupler (B1 and B2), and the diffuse field response of the open ear, measured at the eardrum (C). The combination of these data generate four CORFIG responses, (D1, D2, E1 and E2): D1 is the ITE, 2cc coupler CORFIG: D1 = C - B1 A1; D2 is the BTE, 2cc coupler CORFIG: D2 = C B1 A2; E1 is the ITE, Occluded Ear Simulator CORFIG: E1 = C B2 A1; E2 is the BTE, Occluded Ear Simulator CORFIG: E2 = C B2 A2. One third octave centers A1 A2 B1 B2 C D1 D2 E1 E2 SPL increase at SPL increase at SPL increase at SPL increase at Microphone eardrum re: 2cc eardrum re: ear eardrum re: diffuse location re: diffuse coupler simulator field SPL field SPL SPL increase at Microphone location re: diffuse field SPL 2cc Coupler CORFIG Real Ear to Coupler Difference Freq Microphone location correction Diffuse Field (RECD) Occluded Ear Simulator CORFIG Response of the Occluded Ear ITE MIC BTE MIC 2cc Open Ear ITE CORFIG BTE CORFIG ITE CORFIG BTE CORFIG Simulator Hz db db db db db db db db db

16 4.2 Frequency Response Smoothness (Category 1) Frequency Response Smoothness of a sound reproduction system relates to user experience of fidelity or consistent performance across frequency. A limit on maximum deviation is specified to ensure that sufficient smoothness is achieved. No single peak in the one-third-octave frequency response shall exceed 12 db relative to the average levels of the one-third-octave bands two-thirds octave above and below the peak. Example: A peak at 1.6 khz should be compared to the average of the 1.0 khz and 2.5 khz one-third-octave levels. The frequency response evaluated for this parameter shall be the diffuse field corrected one-third-octave frequency insertion response as specified in Maximum Acoustic Output (Category 1) Maximum Acoustic Output relates to user comfort, in particular to avoid uncomfortably loud sounds. A criterion for maximum output provides a minimum performance standard for user comfort. The maximum OSPL90 output level shall not exceed 120 db SPL measured in a 2cc coupler. Refer to ANSI S for OSPL90 measurement conditions. Note: A 120 db SPL measured in a 2cc coupler is equivalent to a level of approximately 115 dba referred to the sound field. See Annex A for more information. 4.4 Distortion Control Limits (Category 1) Distortion relates to user experience of fidelity or faithful reproduction of the sound input. A maximum criterion for distortion provides a minimum performance standard. The minimum analyzer bandwidth for measuring THD shall be the advertised frequency limits of the device Output Distortion Using a 500 Hz tone as input, the THD+N shall not exceed 5% for outputs of 70 and 100 db SPL. Distortion is to be measured using a 2cc coupler with the device volume control set to maximum and the input sound level to the device adjusted to give the required outputs. Note 1: If a 500 Hz 1/3 rd octave pulsed-noise signal (such as that specific in IEEE-269) is used, then the tests shall be performed with output levels of 67 and 97 db SPL (instead of 70 and 100 db SPL used for sine wave based testing). This adjustment is made to account for the higher peak-to-rms ratio of the 1/3 rd octave pulsed-noise test signal. Note 2: The source of sound can be a hearing device test box or laboratory test system Input Distortion THD+N shall not exceed 5% with a 500-Hz tone input applied to the microphone of the device at a level of 100 db SPL. The device output shall be measured into a 2cc coupler and the volume control should be adjusted to produce an output of 80 db SPL (unweighted). NOTE 1: If a 500 Hz 1/3 rd octave pulsed-noise signal (such as that specific in IEEE-269) is used, then the signal level applied shall be 97 db SPL. This adjustment is made to account for the higher peak-to-rms ratio of the 1/3 rd octave pulsed-noise test signal. 10

17 NOTE 2: A 100 db SPL-rms sine wave has a 103 db peak which corresponds to approximately 90 db SPL-rms speech and music as measured with a sound level meter (Fast). 4.5 Self-generated Noise Levels (Category 1) Self-generated noise relates to noise at the device output that is not present in the input sound. Such noise can potentially mask soft but desirable sounds. A criterion for maximum self-generated noise provides a minimum performance standard. Self-generated noise shall not exceed 32 dba (equivalent SPL) referred to the input. Output shall be measured in a 2cc coupler. Methods that artificially lower the apparent noise floor (e.g., auto-muting, downward expansion) shall be disabled during testing. Category High Frequency Gain Provided (Category 2) The manufacturer shall report the maximum available high-frequency gain. This gain is the average of the 2 cc coupler gains at 1.0, 1.6, and 2.5 khz, measured as per ANSI S with 50 db SPL input. 4.7 Battery Life (Category 2) Battery life is directly related to user experience, expectations, and operating cost. Establishment of a common metric for battery life allows customers to more accurately evaluate and compare devices. Manufacturers shall report the estimated battery life for a single operating charge cycle with all optional features turned on and report the estimated battery life for a single operating charge cycle with all optional features turned off. This would be the time that a single use battery would require replacement or the time required before a rechargeable battery would need to be recharged. If the battery is replaceable, the recommended battery type shall be specified. Estimated battery life in each case is to be calculated from the minimum mah capacity rating of the manufacturer recommended battery divided by the current draw under the stated measurement conditions. Measurement conditions: Input signal: Volume control: Tone control: AGC & noise/feedback suppression: 1 KHz tone at 65 db SPL (measured at the microphone or equivalent direct input) Adjust for 85 db SPL in coupler, or maximum volume control setting Adjust for widest frequency response possible Disable/adjust for minimum effect (where possible) (includes compression & expansion) Where device function is limited by a minimum voltage requirement* that exceeds the battery rated full discharge voltage, the capacity rating shall be de-rated to coincide with the minimum required operating voltage on the typical battery discharge curve for the current discharge rate. * or onset of low battery warning/indication. 11

18 4.8 Latency (Category 2) Latency relates to user experience of temporal fidelity or time alignment of the reproduced sound with the original. The critical aspect of latency relates to the perception of one s own voice when speaking, whereby the signal from the device interacts with one s voice heard naturally through bone and air conduction. Excess latency tends to inhibit speech. Latency should not exceed 15 ms. There are multiple acceptable methods for determining latency. One method is to use a 100 Hz square wave signal wherein the time difference between the leading edges of the input and output waveforms can be observed on an oscilloscope. Another approach is to compare the peak arrival times of the input and output impulse responses. Other approaches are acceptable as well so long as they are accurate and repeatable within 1.5 ms. 4.9 RF-Immunity (Category 2) The manufacturer shall report RF Immunity for wireless device compatibility in both microphone (M) and, if present, telecoil (T) coupling modes. Immunity shall be measured in accordance with ANSI C and the M and T ratings reported. An immunity of M2/T2 or better is recommended. Category Fixed or Level Dependent Frequency Equalization - Tone Control (Category 3) Manufacturers shall report if device tone controls are present and, if so, how they operate. Some tone controls enable a user to adjust the frequency response which is then fixed independent of level. Others change the frequency response versus input level without user interaction, i.e., automatically according to the manufacturer s algorithm. Combinations of the above also exist Level Dependent Gain/Compression (Category 3) Manufacturers should provide qualitative information identifying the functional compression/automatic gain of the device. This description should classify the compression/automatic gain characteristic(s) of the device as Multiband, Single Band, or none (Linear) and whether it is Wide Dynamic Range Compression and/or Limiting SNR Enhancement (Category 3) Directional and remote microphones can enhance the level of a desired sound source (e.g., a preferred talker) relative to background noise or the sound from other sources in the environment. Manufacturers shall report the presence of an omnidirectional microphone, directional microphone, and/or remote microphone (if available) Noise Reduction (Category 3) Beyond the techniques in Section 4.12, other noise-reduction algorithms exist that attempt to mitigate the deleterious effects of noise while minimizing degradation of a desired signal. The manufacturer shall report whether a noise reduction feature is included Feedback Control / Cancellation (Category 3) The manufacturer will indicate whether feedback control/cancellation signal processing is included. 12

19 4.15 Personalization (Category 3) General Current and future technological development may benefit from methods to introduce personalization into the device tuning or functionality. Forms of personalization may be derived from standard referenced psychophysical methodologies or novel proprietary methods. Personal response characteristics which modify the device functionality that may be of benefit to the user include, but are not limited to: a user s hearing thresholds as a function of frequency, hearing performance in various conditions of noise, speech intelligibility in noise, localization resolution, or head-related transfer function specification. Future identified relevant personal response characteristics that improve device functionality for the user should be able to be rapidly introduced into devices whose performance specification is captured by this standard Specification and Reporting While personalization is not a requirement for compliance with this standard, compliance does require reporting a description of any personalized device functionality. This functionality should be described in a way that a user may be able to identify common elements of device personalization across multiple market offerings. For example, a user should be easily able to differentiate between devices that make use of their hearing thresholds from those that do not. The general method for determination of the specific personalized response characteristic that is modifying performance of a particular device should be described or a reference provided Device Coupling to the Ear (Category 3) The manufacturer shall report the fit of the device to the user s ear using the following definitions: Open fit The ear is open to receive sound from the combination of the natural acoustic environmental sounds and electro-acoustically amplified sounds provided from the device. Closed fit The ear is occluded. The ear primarily receives electro-acoustically amplified sounds provided from the device. Adjustable fit The user can adjust the degree of occlusion to the ear. This provides user control between the amount of natural acoustic environmental sounds and the amount of electro-acoustic amplification provided from the device Wireless Connectivity (Category 3) The manufacturer shall report all modes of wireless connectivity supported by the device, for example: none, telecoil, Bluetooth, DECT, Wi-Fi, etc. 5 Reporting The manufacturer shall provide specific information that is readily available to a potential consumer at the point of purchase. The following information shall be included: frequency response bandwidth (see section 4.1), maximum output level (see section 4.3), and a URL with data for all parameters measured and features defined in Section 4. 13

20 Annex A: Maximum Acoustic Output In the design of any device reproducing live sound there is a required development balance to provide undistorted reproduction of content such as live music while at the same time avoiding sudden peak output SPLs which would be uncomfortable to the listener. To optimize this balance, a maximum output level of 120 db is recommended. The National Institute for Occupational Safety and Health (NIOSH) describes in the standard NIOSH-98 that a 115 dba SPL sound field is an acceptable listening level for up to 30 seconds. As shown in Table A.1, a 120 db SPL sound measured in a 2cc coupler is equivalent to a level of approximately 115 dba for a measured sound field. A device with this maximum output should provide the user sufficient time to turn it off or remove it from the ear before it reaches an unacceptable level. However, it is important to recognize that a maximum undistorted output below the levels described above may be inadequate for reproduction of some sounds listeners wish to hear such as unamplified music. For example, the sound level of live symphonies has been measured (C-weighting, Fast) with peak readings of at least db SPL from mid-audience range in a concert hall. To assure that these real-life sonic events, such as the example symphony, are as faithfully represented as possible, a maximum output level of 120 db is recommended. A maximum output level of 120 db (after conversion to equivalent sound field values) should prevent output clipping distortion and support reproduction of the occasional peaks that a listener would want to hear free of distortion. The following tables capture some relevant equivalencies between measured sound fields and the corresponding output levels for different measurement capture systems. For example, a pure-tone sound field level of 117 db SPL at 2 khz corresponds to an output of 120 db SPL as measured in a 2cc coupler (Table A.1) or an output of db SPL as measured in an occluded ear simulator (Table A.2). Tables A.1 and A.2 first convert to the corresponding sound field SPL and then add the A-weighting correction (1.2 db at 2 khz) to transfer the final number to what would be measured in the sound field with a typical sound level meter that reports in dba. 14

21 Freq 2cc RECD Pd/Pdf one SPL at average Eardrum SPL at eardrum third Minus to octave SPL in 2cc coupler pressure SPL in diffuse field centers A weighting Total Correction Hz db db db db Table A. 1: Correction of 2cc coupler SPL to equivalent diffuse-field SPL 15

22 Freq Ear Simulator RECD Pd/Pdf in db one third SPL at average Eardrum SPL at eardrum to octave SPL in diffuse centers minus SPL in RES field A weighting Total Correction Hz db db db db Table A. 2: Correction of Occluded Ear Simulator SPL to equivalent diffuse-field SPL 16

23 Consumer Technology Association Document Improvement Proposal If in the review or use of this document a potential change is made evident for safety, health or technical reasons, please your reason/rationale for the recommended change to standards@ce.org. Consumer Technology Association Technology & Standards Department 1919 S Eads Street, Arlington, VA FAX: (703) standards@ce.org

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