IEEE Std 269-2019 pdf free downlaod – IEEE Standard for Measuring Electroacoustic Performance of Communication Devices.
5. Test equipment, fixtures, and environment
The test equipment, fixtures, and environment generally required to test all the devices covered by this standard are covered in this clause. The specific test equipment required to produce test signals and analyze the resulting output is determined by the test signal and analysis method chosen. The test fixtures are selected based on the type of device under test (i.e., handsets and headsets). The test environment is determined by the type of measurement to be performed.
Calibration minimizes the effects of bias errors in the measurement. All equipment should be calibrated in accordance with the recommendations of the manufacturer before performing the system calibration procedures in Clause 8. Sources of random error in the measurement will remain. These will affect the overall measurement uncertainty. See Annex B.
5.1 Measurement microphones
The sizes and types of measurement microphones are specified in the clauses where their use is required. All microphones used to implement this standard shall comply with the relevant specifications in IEC 61094-4.
5.2 Ear simulators
The fundamental purpose of ear simulators is to test a receiver under conditions that most closely approximate actual use by real persons. Either the Type 3.3 ear simulator (5.2.1) or a fullband ear simulator (5.2.2) shall be used for all measurements and devices, unless the applicable performance specification requires or allows an alternative.
A fullband ear simulator is not the same as the Type 3.3, so the measurement results may not be the same. Both the Type 3.3 and fullband ear simulators have a soft pinna that deforms when the receiver is pressed against it. There will be some acoustic leakage since the ear simulator is almost never completely blocked. Changes in force or position of the receiver against the ear simulator will cause the acoustic leak to vary. Changes in the leak will generally introduce variations in the frequency response, especially at the lower frequency range of the receiver, just as it does on a human ear.
The relationship between position and force will vary depending on the shape of the receiver. Note that the correlation between measurements on ear simulators and on real ears is dependent on the device under test. Translations from DRP to LRP should be provided by the manufacturer, and these should be used if available. Otherwise, the translations in 13.1 should be used.
The type of ear simulator used shall be stated.
Modifications to the ear simulator shall not be made
5.2.1 Type 3.3 ear simulator
The Type 3.3 ear simulator shall comply with the specifications given in ITU-T Recommendation P.57.
The Type 3.3 ear simulator comprises a Type 2 simulator with an anatomical pinna. It simulates the characteristics of the median human ear. It is intended to give results comparable to the typical listening experience for a wide variety of devices.
The Type 3.3 ear simulator is recommended for narrowband and wideband applications. It may also be used for superwideband and fullband applications.
5.2.2 Fullband ear simulator
NOTE—As of this publication, there is no comprehensive standard for a fullband ear simulator. Standardization work by ITU-T in this area is ongoing. In the absence of an applicable standard, this subclause is provisional.
A fullband ear simulator includes an anatomical pinna. It simulates the characteristics of the human ear across the entire range of hearing. It should yield results comparable to the typical listening experience for a wide variety of devices from 20 Hz to 20 kHz.
A fullband ear simulator is recommended for all applications from 20 Hz to 20 kHz. It is preferred for superwideband and fullband devices.
If a fullband ear simulator is used for any tests, the manufacturer and model shall be stated.IEEE Std 269 pdf download.