What is the maximum sound pressure test?

In the EN60950-1:2006 version standard, it is clearly required that the equipment under test should comply with the EN50332 maximum sound pressure test requirements, and the maximum sound pressure related indicators of the object under test need to be measured. Therefore, customers often consult MORLAB about the relevant content of the maximum sound pressure test. We have specially summarized the maximum sound pressure test requirements and their general introduction in this article for readers.

The so-called sound pressure refers to the difference between the pressure P when there is a sound field in the medium and the pressure P0 when there is no sound field. Since the measurement of sound pressure is relatively easy to achieve, other physical quantities such as particle velocity can also be indirectly obtained through the measurement of sound pressure, so this physical quantity is often used in acoustics to describe sound waves.

Then the sound pressure of audio equipment and head-mounted and earphones refers to: when there is a sound wave, the difference between the pressure in the medium and the static pressure, the unit is Pascal (Pa). However, too much pressure of sound waves is extremely harmful to the human body, especially when often using headphones to listen to music at a high volume, it will cause considerable damage to the ears. Therefore, physicists and government-related health organizations have long called for limiting the maximum output sound pressure level of portable music playback devices.

From July 1, 2004, EN50332 has officially come into effect as a mandatory standard for maximum sound pressure in Europe. The scope of its test includes the measurement of maximum headphone sound pressure in all portable devices with headphones or headphone jacks. In this standard, there is a detailed definition of sound pressure level (SPL), which refers to the ratio of the sound pressure at this point to the reference sound pressure, taking the common logarithm and multiplying it by 20, in decibels (dB). The maximum sound pressure level actually refers to the equivalent continuous A-weighted

In the EN50332 standard, a simulated artificial head (HATS) with a standard test ear is used for testing in a standard acoustic test room. The test signal has strict regulations and must be produced according to the standard IEC60268-1. Corresponding to different playback devices, the test signal should be produced according to the corresponding test recording level specified in the standard. During the test, the noise reduction system of the test equipment must be turned off, the volume is adjusted to the maximum, the tone is adjusted to the position where the earphone reaches the maximum sound pressure, the earphone is installed on the standard artificial ear, and a microphone is installed in the artificial ear to collect the sound emitted by the earphone. The maximum sound pressure value (LAeq) of each audio is analyzed and recorded by an audio analyzer. The test will be repeated five times, and each reading needs to be tested for at least 30 seconds. The test result of the maximum sound pressure level will be the average of these five times. For a simple playback device without headphones, its maximum output voltage needs to be measured and evaluated.

This picture is a real picture of the maximum sound pressure system

EN50332-1 maximum sound pressure, that is, the maximum allowable value, shall not exceed 100 dB. EN50332-2 portable product's maximum output voltage shall not exceed 150 mV; Headphone's wideband characteristics voltage shall not be less than 75 mV.

The above is a brief introduction to the maximum sound pressure test of portable audio equipment and head-worn and ear-bud headphones.