IEEE Std 269-2019 pdf download – Measuring Electroacoustic Performance of Communication Devices.
9.2.3 Headset measurement repeatability and averaging When a headset is placed on HATS, the results may vary between sets of measurements due to slight variations in positioning. Accurate and repeatable results can be obtained by making several sets of measurements and averaging the results. A set of measurements shall include send, receive, sidetone, echo frequency response, and level. A set may also include measurements such as distortion and noise. A minimum of five sets of measurements shall be made on each unit tested. The headset shall be completely removed from the ear simulator and remounted for each set. The mean and standard deviation of the level, and each point of the frequency response, shall be calculated in decibels. The standard deviation of receive and send level shall be 1 dB or less. The standard deviation of the receive frequency response curves shall be 2 dB or less from 200 Hz to 3300 Hz, regardless of the device bandwidth. The standard deviation of the send frequency response curves shall be 1 dB or less from 200 Hz to 3300 Hz, regardless of device bandwidth. The accuracy of the final results shall be considered acceptable if the standard deviation requirements are met. Additional sets of measurements may be made to meet these requirements. If the requirements are still not met, the results shall be reported and labeled as “reduced accuracy.” The reported results shall include the means and standard deviations of frequency responses and the output levels. A description of the test position and the number of trials shall also be reported. Sidetone standard deviation can be greater than either send or receive. The standard deviation of the sidetone frequency response and level shall be reported, but there is no requirement. Similarly, a minimum of five measurements of all other parameters should also be made, and the mean should be reported. For maximum acoustic output, at least five measurements shall be made. The final result shall be the maximum of all the measured results.