This standard specifies the reference level of narrow-band masking noise emitted by pure tone audiometer air conduction earphones. The reference level of narrow-band masking noise refers to the value to be added to the pure tone reference equivalent threshold sound pressure level of each corresponding frequency specified in GB/T 4854.1 or GB/T 16402 when the masking earphones are placed on an appropriate acoustic coupling cavity, ear simulator or artificial ear. This standard gives the reference level of 1/3 octave and 1/2 octave bandwidth masking noise. GB/T 4854.4-1999 Reference zero level for acoustic calibration of audiometric equipment Part 4: Reference level of narrow-band masking noise GB/T4854.4-1999 Standard download decompression password: www.bzxz.net
This standard specifies the reference level of narrow-band masking noise emitted by pure tone audiometer air conduction earphones. The reference level of narrowband masking noise refers to the value to be added to the pure tone reference equivalent threshold sound pressure level of each corresponding frequency specified in GB/T 4854.1 or GB/T 16402 when the masking earphone is placed on an appropriate acoustic coupling cavity, ear simulator or artificial ear. This standard gives the reference level of 1/3 octave and 1/2 octave bandwidth masking noise.

GBT 4854.4—1999www.bzxz.net
This standard is equivalent to the international standard 15) 389-4: 1994 "Reference zero level for acoustic calibration of audiometric equipment - Part 4: Reference level for narrow-band masking noise".
This standard provides a unified regulation for the masking noise level in pure tone audiometry, and will play a positive role in standardizing audiometric technology and promoting the development of audiology and international exchanges.
This standard is the fourth standard in the standard series of "Acoustic Calibration Audiometer Equipment Reference Zero Level". The standard series GB/T4854 has 7 standards under the general title "Acoustic Calibration Audiometer Equipment Reference Zero Level", which are GB/T1854.1 Acoustic Calibration Audiometer Equipment Reference Zero Level Pure Tone Reference Equivalent Sound Pressure Level for In-ear Earphones GB/T16102 Acoustic Calibration Audiometer Equipment Reference Zero Level Pure Tone Equivalent Sound Pressure Level for Insert Earphones GB/T 4854.3 Acoustics
GB/T 4854-4
GB/T 4854.5
GB/T 4854.6
GB/T 4854. 7
Benchmark for calibration of audiometric equipment Zero-level bone vibrator pure tone benchmark equivalent sound pressure level for audiometric equipment Zero-level narrowband masking noise benchmark for calibration of audiometric equipment 8~16kH2 frequency range pure tone benchmark equivalent threshold sound pressure level for calibration of audiometric equipment Zero-level short-time release test signal benchmark equivalent wide-field sound pressure level for calibration of audiometric equipment Zero-level free field and diffuse field audiometric calibration When the second standard in the series of GB/T16402 was formulated, it had not yet formed a standard series. When G3/T16402 is revised, its standard number will be changed to GB/T4854.2.2. The fifth and sixth standards in the series are to be determined. Appendix A and Appendix B of this standard are both informative appendices. This standard was proposed and managed by the National Technical Committee for Acoustics Standardization. The drafting units of this standard are: Institute of Ear and Throat, General Hospital of the Chinese People's Liberation Army, Institute of Acoustics, Chinese Academy of Sciences. The main drafters of this standard are Chen Wen, Gu Rui, Zhang Ruwei, Dai Genhua, and You Chunjian. GB/T 4854.41999
ISO Foreword
The International Organization for Standardization (ISO) is a worldwide federation of national standardization committees (ISO member states). The formulation of international standards is usually completed by ISO technical committees: each member state has the right to participate in the technical committee when it is interested in a standard determined by a technical committee, and governmental and non-governmental international organizations related to ISO can also participate in the work. The International Organization for Standardization (ISO) maintains close cooperation with the International Electrotechnical Commission (IEC) in all aspects of electrotechnical standardization. The draft international standards adopted by the technical committees should be distributed to the member states for voting. The draft international standards need at least 7% of the member states to vote in favor before they can be published as international standards. International Standard ISO389-4 was drafted by ISO/TC.43 Acoustics Technical Committee. The first edition of ISO1389-4 replaced ISO 8798: [987. And made a complete revision to it. The general title of ISO 389 is "Acoustics: Fundamental Zero Level for Calibration of Listening Equipment", which includes the following parts: Part 1: Fundamental Equivalent Sound Pressure Level of Pure Tones for On-Aural Earphones Part 2: Reference Equivalent Sound Pressure Level of Pure Tones for Inserted Earphones Part 3: Fundamental Equivalent Sound Pressure Level of Pure Tones for Bone Vibrators; Part 4: Reference Level of Narrow-Band Masking Noise; Part 5, Reference Equivalent Threshold Sound Pressure Level of Pure Tones in the Frequency Range of 8 to 16 kHz; Part 6, Reference Equivalent Threshold Sound Pressure Level of Short-Duration Acoustic Test Signals; Part 7: Reference Audiometry for Free-Field and Diffuse-Field Audiometry. Appendices A and B of this standard are indicative and for reference only. GB/T 4854.4—1999
In pure tone audiometry, in order to prevent the test ear from hearing the test tone, a narrowband noise with the same center frequency as the test pure tone is used. In the non-test ear, the masking noise is generated by the on-ear earphone or insert earphone of the audiometer. GP/T7341.1 stipulates that the effective masking level of the calibrated narrowband masking noise of 1/3 and 172 octaves can just mask the noise level required for a known pure tone hearing level. It is calculated from the known psychoacoustic data of masking to the same ear (that is, the masking noise and the masked pure tone are transmitted to the same test ear through the same earphone). In most cases of audiometry, a headphone is used to mask the non-test ear. For the test ear, the pure tone sound pressure level from the headphone will be affected by the bone attenuation and the blocking effect of the masking headphone. These phenomena must be taken into account when adding masking during audiometry. 1 Scope
National Standard of the People's Republic of China
Reference level for the calibration of audiometric equipment
Part 4: Reference levels far narrow-band masking noiseGB/T 4854.4—1999
eqvISO 389-4:1994
This standard specifies the reference level of narrow-band masking noise emitted by pure tone audiometer air conduction earphones. The reference level of narrow-band masking sound refers to the value to be added to the pure tone reference equivalent sound pressure level of each corresponding frequency specified in GB/T4854.1 or GB/T16402 when the masking sensitive earphones are placed in an appropriate acoustic coupling cavity, ear simulator or artificial ear. This standard gives the reference level of 1/3 octave and 1/2 octave bandwidth cut-off noise. Note: Some comments on the derivation of reference levels are given in Appendix A. 2 Referenced Standards
The provisions contained in the following standards are all the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision. Parties using this standard should discuss the possibility of using the latest version of the following standards: GB/T4851.1-1999 Acoustic calibration of audiometric equipment - Reference zero level - Part 1: Reference equivalent sound level for pure tones of on-ear headphones (eqv IS0 GB/T7341.1—1998 Hearing - Part 1: Pure tone audiometer (IdtIFC:645-1:1992) GB/T7342—1987 IEC: Temporary reference coupler for calibration of audiometric headphones (eq[EC303,1970) GB/T7614-1987 Wide band artificial ear for calibration of audiometric headphones (cqVIEC:318:1970) GB/T16402-1996 Acoustic insert earphones - Pure tone reference equivalent valve sound pressure level (eV1S0389-2:1991) S1/Z9144--1987 TEC reference coupler for measuring rigid hearing aids SJ/T10659--1995 Occluded ear simulator for measuring insert earphones 3 Definitions
This standard adopts the following definitions.
3.1 Bone conduction
The mechanical vibration of the skull is stimulated to transmit sound to the inner ear. 3.2 Masking
a) The phenomenon that the hearing of one sound is gradually increased due to the presence of another masking sound. h) When measuring the hearing of one ear, noise is often added to the other ear to avoid affecting the hearing of the other ear. 3.3 Effective masking level (of a noise bar) When the presence of a noise with the same frequency as the pure tone makes the hearing of the pure tone increase, the hearing level of the pure tone is equal to the hearing level of the pure tone.
Approved by the State Administration of Quality and Technical Supervision on March 8, 1999, and implemented on September 1, 1999
3.4 ​​Narrow-band noise GB/T 4854. 4—1999
Internal noise with continuous spectrum and constant power spectrum density, produced by a bandpass filter with basically constant attenuation outside the passband (see 3.6),
3.5 Pure-tone audiometer Electroacoustic instrument with headphones that can provide pure tones of known sound pressure level at a specified frequency. In addition, it may also have a bone vibrator and/or masking conditions,
3.6 Noise bandwidth noise bandwidth
The difference between the cut-off frequencies of the high and low side bands of the noise band. At the cut-off frequency, the noise harmonic density drops to one card of the center frequency of the noise band.
3.7 Critical bandwidth for masking The width of the broadband continuous noise spectrum that can effectively mask pure tones with frequencies that coincide with the center frequency of the band. 3.8 Reference level for narrow-band masking noise For a specified acoustic coupling chamber, ear simulator or artificial ear, in order to obtain an effective masking level equivalent to 0B, the sound pressure level that needs to be added to the base-value equivalent sound pressure level of a pure tone with the same frequency as the case noise is the reference level of the narrow-band masking noise.
Certification: SJ/Z9144, GB/T7342, SJ/T1085 and H/T7614 respectively specify the acoustic coupling chamber, ear simulator and real ear. 3.9 Occlusive effect Occlusive effect The phenomenon that blocking the ear with earphones or earplugs will form a closed air-filled cavity between the outer ear and the earphone or in the external auditory canal, thereby reducing the bone conduction hearing level of the ear. The occlusive effect is obvious at low frequencies. 4 Technical requirements
Base level of pure tone audiometry narrowband masking noise is shown in Table 1. When the masking headphones are placed on an appropriate coupling chamber, simulator or simulator in accordance with GB/T7842, (i: B/T7614. SJ/Z144 or SJ/T10659, the data given in the table shall be added to the reference equivalent tuning level of the corresponding pure tone frequency in accordance with GB/T4854.1 or GB/T16402. The base level of any noise bandwidth between 1/2 and 1/3 octave can be obtained by interpolation. Table! Base level of narrowband masking noise
Center frequency, H
1/3 frequency band
Base level, BB
Bandwidth 1/2 octave
Center frequency, F
GB/T 4854.4—1999
Table 1 ()
Grid width 1/3 octave
Base band, d11
Bandwidth 1/2 octave
GB/T 4854.4 -1999
Agglomeration A
(Instructive Appendix)
Some notes on the derivation of reference level
The derivation of reference level is based on the following assumptions: When the noise has a noise-to-noise ratio of -4dB in the critical bandwidth, it can effectively mask the pure tone with the same center frequency (which is independent of frequency). This assumption and the critical bandwidth value used are cited from the literature listed in Appendix B. It is also assumed that the noise power spectral density in the passband is basically constant. The method for calculating the reference level is as follows:
a) When the noise bandwidth is less than the critical bandwidth, the reference level of the band masking noise, L is 4dB. b) When the noise bandwidth exceeds the critical bandwidth, the reference level of the narrow-band masking noise, △ (dB) is calculated according to formula (A1): Al - 4 + 1algLb(f)/c(fi
wherein; the noise bandwidth with center frequency, z
the critical bandwidth with center frequency f, Hz.
Table A1 gives the critical bandwidth values ​​used to calculate the reference level of the narrow-band masking noise in Table 1. The relationship between the critical bandwidth and the center frequency, tt|| H
Critical bandwidth\(),11z
Center frequency, Hz
Critical bandwidth-r(), Hz
1) For center frequency less than 5(0Hz, the critical bandwidth is taken as the approximate value in Hz; for center frequency greater than 5000Hz, the critical bandwidth is taken as the approximate value in 511z.
Appendix B
(Suggested Appendix)
References
21JGB/T4854.3-1998 Acoustic calibration audiometric equipment reference zero level Part 3: Back vibration pure tone reference equivalent level
[2]GB/T7341.1—1998 Audiometer Part 1: Pure tone audiometer[3I Srhatf, B, Critieal bands. Foundations of modern aurtitory theory (ed. Tobies, JV ). Vol.I, Academic Press, New York. l970.[4J Zwicker, F. and Feldikeller. R. Das Ohr als Nachrichtencmpianger. S. Hirzcl Vcrlag,Stiigart, 1967.
GB/T 4854.4—1999
[5] Zwicker, F. and Terhardt, F. Analytical expressions for rritical-band rate and critical bandwidth as a function of frequency. J.Acoust. Soc. Amer., 68(5), 1980, pp. 1523~1525[4J Zwicker, F. and Feldikeller. R. Das Ohr als Nachrichtencmpianger. S. Hirzcl Vcrlag,Stiigart, 1967.
GB/T 4854.4—1999
[5] Zwicker, F. and Terhardt , F. Analytical expressions for rritical-band rate and critical bandwidth as a function of frequency. J.Acoust. Soc. Amer., 68(5), 1980, pp. 1523~1525[4J Zwicker, F. and Feldikeller. R. Das Ohr als Nachrichtencmpianger. S. Hirzcl Vcrlag,Stiigart, 1967.
GB/T 4854.4—1999
[5] Zwicker, F. and Terhardt , F. Analytical expressions for rritical-band rate and critical bandwidth as a function of frequency. J.Acoust. Soc. Amer., 68(5), 1980, pp. 1523~1525
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