The anechoic chamber is mainly used for acoustic testing of products, and its design purpose is to provide an environment that approximates a free sound field to reduce the influence of external noise and reflected sound on the test results. The background noise level of the anechoic chamber is usually required to be below 25 decibels to ensure the accuracy of the test.
 
Specifically, the background noise level of the anechoic chamber can be determined based on the sound pressure level of the subject's sound source. In general, it is required that the difference in sound pressure level between the subject's sound source and the background noise in each frequency band under study be at least 10dB. This means that the anechoic chamber can measure a range from very low noise levels (such as below 10 decibels) to higher noise levels (such as above 100 decibels).
 
The acoustic effect and measurement range of an anechoic chamber also depend on its design and construction quality. A high-quality anechoic chamber can achieve lower background noise levels, allowing for the measurement of even fainter sounds. For example, the background noise in some advanced anechoic chambers can be as low as 10 decibels or even lower.
 
In summary, anechoic chambers can measure noise levels ranging from very low to high, depending on the design and construction quality of the chamber, as well as the sound pressure level of the tested sound source.