Acoustics-Audiometric test methods-Part 2: Sound field audiometry with pure tone and narrow-band test signals
Some standard content:
GB/T 16296—1996
This standard is formulated based on the International Organization for Standardization's standard TS()8253-2≤Acoustics-Audiometry Methods, Part 2: Sound Field Audiometry with Pure Tone and Narrow-Band Test Signals (1992-11 First Edition). As this international standard is technically mature and widely promoted internationally, it will play a driving role in ensuring the unification of hearing values in my country, and will be adopted equivalently to meet the needs of international technical exchanges and the adoption of international standards as soon as possible. This standard shall be implemented from November 1, 1996. Appendix A, Appendix B and Appendix C of this standard are all indicative appendices. This standard was proposed by the State Administration of Technical Supervision, approved by the Basic Branch of the National Acoustic Standardization Technical Committee, and managed by the China Institute of Metrology and Basic Sciences; the drafting unit of this standard is: China Institute of Metrology; the main drafters of this standard are: Zhang Jucai, Shen Yang, Shuai Zhengping, Qiu Jianhua. This standard is entrusted to the China Institute of Metrology for interpretation. GB/T 16296-1996
ISO before
ISO (International Organization for Standardization) is a worldwide alliance of national standards bodies (ISO member bodies). The work of formulating international standards is usually carried out through ISO technical committees. Each member body interested in the subject determined by the technical committee has the right to attend the committee. International organizations of both governmental and non-governmental nature that have relations with ISO may also participate in its work. ISO cooperates closely with the International Electrotechnical Commission (IEC) on all electrotechnical standard issues. Draft international standards adopted by the technical committee are circulated to the member bodies for voting. The publication of an international standard requires the approval of at least 75% of the voting member bodies.
International standard ISO8253-2 was developed by ISOTC43 Acoustics Technical Committee. 1S08253 contains the following parts under the general title "Acoustics-Audiometry methods":-Part 1: Basic pure tone air conduction and bone conduction network measurement: Part 2: Sound field audiometry with pure tone and narrow-band test signals:-Part 3 Speech listening.
Appendices A, B, and C of this part of ISO8253 are for reference only.
National Standard of the People's Republic of China
Audiometry methods-Part 2: Sound field audiometry with pure tone and
Narrow-band test signals
Acoustics—Audiometrytestmethods—Part 2: Sound field audiometry with pure tone andnarrow-band test signals
GB/T 162961996
eqvISO 8253-2:1992
This standard is equivalent to ISO8253-2 Acoustics-Audiometry Methods-Part 2, Sound Field Audiometry Using Pure Tones and Pull-Through Test Signals". Part 2 of the Audiometry Method Standard summarizes the method of providing pure tones to subjects using headphones or bone vibrators to determine the listening network. This standard summarizes the method of determining the listening network in the sound field. Usually, sound field testing means listening to the test signal provided by one or more loudspeakers with both ears in the test room. The test signal can be a pure tone, FM tone or narrowband noise. The acoustic characteristics of the sound field depend on the choice of test signal, the loudspeakers used, and the sound field. The number and acoustic performance of the test room, as well as the acoustic characteristics of the test room: Sound field audiometry can be used for a variety of purposes, such as the assessment of hearing acuity of young people, and the determination of the functional gain of hearing aids used by specific hearing aid wearers.
1 Scope
This standard specifies the requirements for test signal characteristics, free field, diffuse sound field and quasi-free field; the steps for sound field audiometry using pure tone, FM tone or other narrowband noise test signals provided by one or more loudspeakers, the main purpose of which is to determine the hearing valve level in the frequency range of 125 to 12500 Hz:
This The standard does not include technical requirements for the use of hand-held loudspeakers. This standard does not include the use of language as a test signal. The purpose of this standard is to ensure that hearing tests performed using sound field audiometry give the highest possible accuracy and reproducibility. Appendix A (suggestive appendix) gives examples of graphical representations of results, and Appendix C (suggestive appendix) gives references. 2 Cited standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of the standard, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards: GB3240-82 Frequencies commonly used in acoustic measurements GB3241-82 1/1 and 1/3 octave filters for sound and vibration analysis GB3785-83 Electrical and acoustic properties and test methods of sound level meters GB4963-85 Standard equal loudness contours for pure tones in free field GB7313-87 Minimum performance requirements and measurement methods for high-fidelity loudspeaker systems 1S08253-11989 Acoustic hearing test methods Part 1: Basic audiometry for pure tone air conduction and bone conduction hearing IEC645-1:1992 Audiometer Part 1, Pure tone audiometer Approved by the State Technical Supervision Bureau on April 12, 1996, and implemented on November 1, 1996
3 Definitions
This standard adopts the following definitions.
3.1 Air conduction
GB/T 16296—1996
The transmission of sound from the outer ear and middle ear to the inner ear. 3.2 Otologically normal person is a person with normal health, without any ear disease or symptom, with no obstruction of the ear canal and no history of excessive noise exposure. 3.3 Threshold af hearing The sound level at which 50% of the correct perception responses can be made under specified conditions for a specified number of tests. 3.4 Threshold sound pressure level For a certain listener, a specified signal and its specified appearance, in a specified sound field, at the test position, the sound pressure level of the reference point measured when the listener is not present, corresponding to the hearing when the listener is present. 3.5 Reference sound pressure level refererice threshold sound pressure level The median of the sound pressure levels of a sufficient number of male and female subjects aged 18 to 30 years with normal otology for a specified signal and its specified appearance, used to represent the reference point in a certain sound field. 3.6 Hearing level hearing level
For a specified signal and its specified appearance, at a reference point in a specified sound field, the specified signal sound pressure level minus the corresponding reference sound pressure level.
3.7 Hearing threshold level For a specified signal and a specified sound field, the hearing level expressed in hearing level or sound pressure level. 3.8 Carrier frequency of frequency-modulated tones carrier frequency a frequency-modulated tones periodically varying pure tone frequencies. The carrier frequency is designated as the standard test frequency. 3.9 Frequency deviation
The maximum difference between the instantaneous frequency of the frequency-modulated tones and the carrier frequency. 3.10 Reference Point: The midpoint of the straight line connecting the two ear canal openings of the subject when the subject is located at the test position in the sound field. 3.11 Reference axis: The axis perpendicular to the radiation surface of the loudspeaker. For a single radiator or horn loudspeaker, the axis passes through the geometric center of the diaphragm or horn. For a composite loudspeaker, the axis position is specified by the manufacturer. 3.12 Free sound field: The sound field in which the effect of the room boundary on the sound wave is negligible. 3.13 Quasi-free sound field: The sound field in which the effect of the room boundary on the sound wave is moderate, and it meets the requirements of 5.3. 3.14 Diffuse sound field: The sound field that can provide a statistically uniform energy distribution area. In a given area, the propagation direction of the sound at any point is randomly distributed. 3.15 White noise: The noise with power spectrum density and frequency is independent. 3.16 Noise bandwidth noisebandwidth
The difference between the noise band quotient and the lower edge frequency. At these two frequencies, the noise power spectrum density drops to half of its average value within the noise band, 3.17 Centre frequency of the noise band The geometric mean of the two edge frequencies of the noise bandwidth. 3.18 Functional gain of the hearing aid For a specified test signal, a specified sound field type and a specified signal presentation method, for a specific subject, the difference in hearing with and without a hearing aid.
4 Test signal characteristics
CB/T 16296—1996
The test signals of this standard include pure tones, FM tones and narrowband noise. 4.1 Pure tones
Pure tones are used in the free field required by 5.1. Note 1 For other types of sound fields, the standing wave relationship will cause the pure tone to show a large spatial variation in the sound pressure level. When a fixed frequency test tone is used, the frequency selection should be the frequency given in IEC645-1 or GB3240. The actual frequency should be within ±2% of the nominal frequency, which is equivalent to the specifications of a type 2 audiometer that meets the requirements of IEC645-1. 4.2 Frequency Modulated Tone (FM)
Frequency Modulated Tone (FM) is determined by the following characteristics and shall be presented in the report: a) carrier frequency, b) waveform of the modulating signal, c) repetition rate of the modulating signal, d) frequency deviation.
The carrier frequency shall be selected from the test frequency specified in IEC615-1 or GB3240. The waveform of the modulating signal shall be sine or triangular, with symmetrical rise and fall parts on a linear or logarithmic frequency scale. The carrier frequency shall be within ±3% of its standard frequency: the repetition rate of the modulating signal shall be within the range of 4 to 20 Hz, with a tolerance of ±10% of its standard value. The frequency deviation shall be within the range of ±2.5% to ±12.5%, with a tolerance of ±10% of its nominal value. If the modulating waveform is sinusoidal, its total harmonic distortion shall not exceed 5. If it is a triangle, the deviation of the two slopes from the straight line shape should not exceed 5% of the amplitude, and the time difference between the rising and falling parts should not exceed 10%. 4.3 Narrowband noise
The center frequency and bandwidth of narrowband noise should be consistent with the tolerance requirements of filter frequency and rated response of GB3241, or meet the specifications of IEC6451 narrowband masking noise. The center frequency and bandwidth should be mentioned in the report. Note 2 When the bandwidth exceeds 1/3 octave, the reference reading sound pressure level will be different from the value applicable to the 1/3 octave bandwidth. Note 3 The signal power outside the passband depends mainly on the slope of the filter and the cut-off characteristics, which will affect the results of the sound field audiometry, especially for subjects with hearing loss.
4.4 Harmonic distortion
If pure tone is used as the test signal, the linearity of the entire system should be: the total harmonic distortion at 125Hz does not exceed 5%, and does not exceed 3% at 250Hz, 500Hz and 1000Hz when the acoustic measurement is made at the reference point of the test room. These conditions should be met over the full dynamic range provided.
Note 4 It is usually sufficient to measure the spectral distortion at the maximum output sound pressure level provided. The harmonic distortion of the loudspeaker can be tested only in the free sound field. When there is only a quasi-free field or a diffuse field, the harmonic distortion can be measured electrically only at the input of the loudspeaker. The total harmonic distortion should be less than 1%, and the loudspeaker should meet the specifications of Chapter 10 of GB7313. If there is no pure tone as the test signal, an external pure tone generator should be connected to replace the original test signal source to test the linearity of the equipment. When narrow-band noise is used as the test signal, the output level of the external pure tone generator should be 9 dB above the root mean square (RMS) value generated by the test signal source in normal use. When frequency modulated tone (FM) is used as the test signal, the root mean square (RMS) output level of the external pure tone generator should be equal to the output level of the test signal source in normal use. The appearance of the gate No. 4.5 signal can be a single burst sound with a duration of 1 to 2, or it can be repeated gated on and off. When pure tone is used as the test signal for electrical testing at the speaker end, the rise/fall time, on/off time, on/off ratio, undershoot and overshoot characteristics given in IEC645-1 should meet the requirements when pure tone is used as the test signal for electrical testing at both ends of the speaker. NOTE 5 The reverberation time of the test room can have a significant effect on the attenuation of the acoustic test signal. 4.6 Signal level control
4.6.1 Adjustment range
The signal level shall be adjustable in steps of 5 dB or less. 4.6.2 Accuracy
When the acoustic test is made at the reference point, the maximum cumulative error between any two signal level steps over the entire signal range of the attenuator shall not exceed 3 dB. Other specifications specified in IEC645-1 shall also be met. 4.6.3 Dynamic range
The test signal hearing level at the reference point shall cover at least the range of 0 to 80 dB in the frequency range of 500 Hz to 6 000 Hz. NOTE 6 It is also desirable to achieve the same test signal hearing level range outside this frequency range. 4 Method and scale of calibration
The equipment used shall be able to adjust the output level of each test tone individually. The scale shall be expressed in hearing level or sound pressure level. The measurement should be made with a sound level meter of type GB37851. For pure tones and 1/3 octave band noise in the front incident sound field, and for the 1/3 octave band noise in the diffuse sound field, the reference threshold sound pressure level corresponding to normal binaural hearing specified in GB9463 must be used as the reference threshold sound pressure level for sound field audiometry. These data should also be used to meet the requirements of 4.2 for frequency modulated tones (FM). There is no standardized data for other combinations of test signals and sound field types. Note 7 In practice, other incident angles, such as 45°, can also be used. There is no standardized reference sound pressure level in the specification, but the compensation values for 15° and 90° incidence are given in Appendix B (indicative appendix).
Characteristics 8 In use, only two listening conditions (such as wearing and not wearing hearing aids) are determined, and the listening difference relative to the test sound pressure level can be satisfied. 5 Sound field characteristics
The environment used for sound field audiometry can vary greatly. In fact, three suitable sound fields can be established to meet most situations. Two are specified, namely free field and diffuse sound field. But in fact it is impossible to fully meet these two specifications. For this reason, a third sound field that meets this standard is proposed, namely the free field. The user can decide which specification is more suitable for the sound field under consideration. In addition to using the directional microphone given in 5.2 of this standard to measure the sound pressure level, the measurement with the sound level meter must comply with the Type 1 index of GB3785, and the signal used for the test sound field must be the same as that used for audiometry. 5.1 Free field
To establish free field conditions, the following requirements must be met! The loudspeaker is located at the waist of the seated subject, and the reference axis passes through the reference point. The distance between the reference point and the loudspeaker is at least 1m.
b) When the subject and his/her seat are not present, the sound pressure level of the loudspeaker at a position 0.15 m to the left, right, above and below the reference point outside the reference point shall not deviate from its value at the reference point by more than ±1 dB for any test frequency including 4000 Hz, and by less than ±2 dB for any test signal above 4000 Hz. The difference in sound pressure level between the left and right positions shall not exceed 3 dB for any frequency above 4000 Hz. c) When the subject and his/her seat are not present, the difference in sound pressure level of the loudspeaker at the reference output 0.15 m before and 0.15 m after the reference point shall not deviate from the theoretical value of the sound pressure inverse distance law for any test signal by more than ±1 dB. NOTE 9 The above requirements can only be met in an anechoic chamber. 5.2 Diffuse sound field
To establish a diffuse field, the following requirements must be met: a) When the subject and his seat are not present, use an omnidirectional microphone to measure the sound pressure level at the reference point at 0.15°. The deviation of the sound pressure level at the front, back, left, right, top and bottom positions from the reference point shall not exceed 2.5dB for any test signal. The difference between the sound pressure levels at the left and right extreme positions should not exceed 3dB. The microphone orientation should remain the same at each position. GB/T 16296—1996
h) At frequencies of 500Hz and above, when a directional microphone with a normal incidence-random sensitivity index of 5dB is used to measure the incident sound energy, the deviation of the sound pressure level in the directions of the two maximum and minimum readings at the reference point should be within 5dB. For other directional microphones, the relationship between the normal incidence-random sensitivity index and the permissible sound field variation is given in Table 1. 5.3 Quasi-free field
In order to establish quasi-free field conditions, the following requirements must be met. a) The loudspeaker should be placed at the head height of the seated subject, with the reference axis passing through the reference point. The distance between the reference point and the loudspeaker reference point should be at least 1m:
b) When the subject and his seat are not present, and all other normal working conditions remain unchanged, the loudspeaker is 0.000 meters to the left, right, up and down from the axis of the reference point.The sound pressure level at the 15m position shall not deviate from the sound pressure level at the reference point by more than ±2dB for any test signal. c) When the subject and his seat are not present, the difference in the sound pressure level of the loudspeaker at 0.10m before and 0.10m after the reference point on the reference axis shall not deviate from the theoretical value of the inverse law of sound pressure distance by more than ±1dB for any test signal. The useful frequency range of the quasi-free field is given by the frequency range required above. Table 1: Microphone requirements for diffuse sound field measurements, dB Normal incidence-random sensitivity index of loudspeaker 5
Allowed sound field variation
Microphone is not suitable
1 The test should be carried out in enough directions, which depends on the type of microphone and the characteristics of the field microphone arrangement. However, at least two planes where the maximum sound level and the minimum sound pressure level may be obtained should be included.
2 In order to obtain the desired sound field, more than one loudspeaker should be used, and it is required to be fed with non-phase electrical conductance that will reduce the standing wave effect. 6 Ambient noise level in the test room
The ambient noise level in the test room shall meet the requirements given in Table 2. In a specific test room, if the minimum hearing level measured is not the minimum hearing threshold, the appropriate maximum ambient sound pressure level is the value in Table 2, i.e. the minimum hearing threshold measured. Table 2 Maximum allowable ambient sound pressure level for sound field audiometry Lx1/3 octave band Maximum allowable ambient sound pressure level ar (reference, 20 μPa) Center frequency of 1/3 octave band
Minimum test audio frequency
250 Hz
Center frequency of 1/3 octave band
CB/T 16296—1996
Continued Table 2
Maximum allowable ambient sound pressure level Lau (reference, 20 μPa) dB
Minimum test audio frequency
250 Hz
1 When using the data in Table 2, the lowest audiometric level measured is B, and the maximum uncertainty due to ambient noise is 2. If the maximum uncertainty due to ambient noise is allowed to be +5, then the values in Table 2 can be increased by 8d. This value is derived from the double listening condition specified in Part 1 of the audiometric method standard.
2 When narrow-band noise is used as the test signal, the maximum allowable ambient sound pressure level should be appropriately lower than the value given in Table 2. 3 Most current sound level meters can also measure sound pressure levels below 5 dB. 7 Preparation and training of test subjects
For the preparation and training of test subjects, as well as other conditions for hearing tests, the requirements and procedures given in 4.6, 5.1 and 5.2 of Part 1 of the audiometric method standard can be applied. In addition, the subjects should be told to keep their heads at the reference point, facing the required direction, and prevent movement.
Note 15 Some measures can be taken to help the subjects maintain the head position. 8 Determination of hearing levels
Hearing tests may be made using manual, dynamic recording or computer-controlled audiometers. The test may be either monaural or binaural. The location of the reference point relative to the loudspeaker shall be clearly defined and identified. During the test, the test stimulus pattern shall remain constant and shall be noted on the audiogram. When manual or computer-controlled audiometers are used, the order of presentation of the signals shall be from 1000 Hz upwards and then to lower frequencies: repeat the test for 1000 Hz. The presentation of the test signals, the blocking and test procedures, and the determination and calculation of hearing levels shall conform to the relevant requirements of 6.2 to 6.4 of Part 1 of the audiometric method standard. NOTE 11 For low-frequency signals at high levels, the sensory perception of the test signal shall be considered. 8.1 Monaural Test
GB/T162961996
If only one ear is tested, a hearing protector or masking should be added to the non-test ear: Narrowband noise masking is used only when pure tone or frequency modulated tone (FM) is used as the test signal. No noise masking is used when narrowband noise is used as the test signal. The model of the hearing protector used for the non-test ear should be mentioned in the report.
Note 12 In practice, the sound attenuation achieved by blocking the ear is usually limited, which may lead to measurement errors, especially when the hearing of the test ear is worse than that of the non-test ear.
Note 13 When masking is used, it is better to use plug-in headphones to provide masking sound. 8.2 Binaural Test
In binaural testing, it is usually impossible for the subject to determine whether the test signal is heard in one ear or both ears. Therefore, the hearing threshold level determined by binaural testing is the value determined by the binaural hearing threshold or mainly by the more sensitive ear. NOTE 14 The subject may be told where the test signal is to be presented, such as on the left or right side, but he must remember that his main task is to respond to the weakest signal.
9 Avoiding hearing aid testing
If the functional gain of the hearing aid of the wearer is to be determined, the procedures given in clauses 7 and 8 shall be applied. 10 Screening test
Sound field screening audiometry shall be carried out in accordance with Part 1, Chapter 9 of the audiometry method standard. NOTE 15 Sometimes a hand-held microphone is used for sound field selection. The change in the distance between the microphone and the subject will cause a large deviation in the sound pressure level. Therefore, the test conditions will not meet the requirements of Chapter 5.
11 Reporting of Data
The following should be reported with the sound field audiometry results: type of sound field,
- type of audiometer used (manual, automatic recording or computer controlled); Www.bzxZ.net
- position of the subject relative to the loudspeaker;
- identification of the reference for the signal level scale (in terms of hearing level or sound pressure level);
- lowest measurable hearing level other than 0 dB due to ambient noise;
- if only one ear is tested, which non-test ear is blocked and if it is blocked;
if screening audiometry is performed, the screening hearing level. 11.1 Equipment calibrated with hearing levels
If sound field testing is performed with equipment calibrated with hearing levels, the results should be tabulated and an audiogram drawn (see Audiometry Methods, Part I, Chapter 10). Examples of symbols and audiograms are shown in Appendix A (Informative Appendix). The resulting audiogram should be consistent with the sound field used. Masking or blocking of the non-test ear should be noted.
11.2 Equipment calibrated with sound pressure level
If the equipment used for sound field testing is calibrated with sound pressure level, the test shall tabulate the results or give a graphic representation. See Appendix A (indicative appendix) for examples. Note 16 It is recommended to use the same scale for the horizontal and vertical axes as in the audiogram of 11.1, but with the vertical axes in opposite directions and to make appropriate labels. 12 Maintenance and calibration of equipment
12.1 General
Proper calibration of audiometric equipment is essential for reliable results. The following scheme is proposed, which includes a three-stage inspection and calibration procedure: Stage A: Routine inspection and audition;
Stage B: Periodic electroacoustic testing,
Stage C: Basic calibration test.
12.2 Intervals between tests
GB/T 16296-1996
The intervals between the various tests are only a guide. However, unless it is clearly more appropriate to have different intervals, the weekly inspections of Phase A should be carried out, and the intervals between the sound pressure level tests at different reference points should not exceed 3 months. The ideal intervals for the periodic electroacoustic tests of Phase B are 3 to 6 months, and should not exceed one year unless there are special circumstances. NOTE 17 Depending on the specific equipment and experience in use, the intervals of 3 to 6 months may be different. As long as the inspections of Phase A are carried out regularly and with care, the intervals can be longer. If the tests of Phase A and B are carried out regularly, the basic calibration tests of Phase C can be arranged on an irregular basis. The tests of Phase C are only carried out when the equipment is put into use, or when the equipment is replaced and major maintenance is carried out, or when there is a lot of use, and it is suspected that the equipment performance does not fully meet the requirements of the specifications, but the intervals between the tests of Phase VII should not exceed 5 years. 12.3 Phase A: Routine Inspection and Audition
The purpose of routine inspections is to ensure that the equipment is working as well as possible and that the calibration has not changed significantly. The environmental noise conditions of the inspection should be equivalent to those under normal use of the equipment. The inspection procedure is as follows: a) Clean the equipment and check all parts. Check the plug and cable for wear and damage, and replace damaged or severely worn wires; b) Connect the standby power supply and preheat for the recommended time or at least 5 minutes. Perform the start-up procedure specified by the manufacturer; c) Ensure that the reference point is in the correct position and can be clearly identified. d) Use a person who can just listen to the test signal to verify that the output of the audiometer and the ambient noise are approximately correct. The listener has a known hearing level within the normal range. Test with an appropriate test signal. Note 18 Use the same person for each test.
e) Listen to the test sounds for all applicable functions and all provided test signals at a higher hearing level, such as 60dB to 70dB or equivalent sound pressure level. Determine whether the functions are normal, without distortion, without the "click" sound of the blocker, etc. f) Listen for hum or noise at a low hearing level, or any other unwanted sound from the audiometer or test environment. Confirm that the attenuator can indeed attenuate the signal at all times and that no sound radiated by the equipment can be heard at the subject's position. g) Check whether the subject response system, as well as the intercom and monitoring lines are working correctly. 12.4 Phase B: Periodic electroacoustic test
Periodic electroacoustic test is to measure according to appropriate standards and compare the results. The measurement basis of pure tone signal is as follows: a) Frequency of test signal:
b) Sound pressure level at reference point:
c) Attenuation range (over the entire useful range): d) Wave distortion
e) Masking noise level.
For signals other than pure tone, the measurement of ) and α) can be carried out with special spectrum analysis equipment and only when the equipment is suspected of failure.
The sound pressure level measurement must be carried out with a sound level meter that complies with GB37851. In addition, routine inspection and audition must be carried out according to Phase A. 12.5 Phase C: Basic calibration
Basic calibration should ensure that the listening equipment, sound field and ambient noise level meet the relevant specifications. If the acoustic characteristics of the test room change, such as changing the location of the device, instrument or ambient noise source, a basic calibration should be carried out and the sound field characteristics should be measured according to Chapter 5.
Examples are shown in Figures A1 and A2.
GB/T 16296
Appendix A
(Suggestive Appendix)
Graphic representation of results
When the results are presented as an audiogram, the sound field type and other parameters must be identified. It is recommended to use the symbols in Table A1. Table A1 Symbols for test conditions
Recording of measured hearing threshold
Monaural, left
Monaural, right
Monaural, left ear with hearing aid
Monaural, right ear with hearing aid
Both ears with hearing aids
Symbol:
×2 Left monoaural hearing width
Left monoaural hearing aid hearing valve
Frequency, Hz
Hearing threshold level
Symbol:
160200
GB/T 16296- 1996
315400
Right monoaural audiometry:
630800125016002500315050006311010000Suo
Yes Monoaural hearing aid
Frequency, Hz
Figure A2 Sound pressure level of hearing valve
Appendix B
(Reminder Appendix)
Positive values for 45° and 90° incident angles
For various reasons, not all sound field audiometry uses a loudspeaker with 0° incidence (directly on-axis position). Actual surveys show that the commonly used incident angles for off-axis positions are 45° and 90°. Table B1 gives the sound pressure level that should be increased for the test frequency from 200 Hz to 12500 Hz at 45° and 90° incident angles (see Appendix C (Suggested Appendix) Document (5)). Table B1 The sound pressure level that should be increased for the ear closest to the speaker Test pass rate
Correction value for sound incident angle\
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