The Impact of Exam Room Signal Blockers on FM Radio Broadcasting during English Listening Tests

Every year, a number of universities organize the College English Test (CET) in China, which includes the four and six levels of English proficiency. These exams are conducted in standardized exam rooms, equipped with signal blockers as a crucial means to prevent cheating. However, concerns have been raised regarding the potential impact of signal blockers on FM radio broadcasting during the listening test. This article aims to analyze the basic working principle of signal blockers and discuss their potential influence on FM radio broadcasting.

The Working Principle of Signal Blockers:

Signal blockers emit radio frequency interference signals that are designed to disrupt commonly used cheating tools such as mobile phone signals, WiFi signals, and wireless data transmission. The frequency range covered by signal blockers is significantly different from the frequency range used by FM radio broadcasting systems, which typically operate within the range of 70-110MHz. Therefore, in theory, signal blockers should not interfere with FM radio broadcasting.

Potential Influence on FM Radio Broadcasting:

Although there should be no interference between signal blockers and FM radio broadcasting based on their respective frequency ranges, it is necessary to consider the variations in emission frequencies among different signal blocker manufacturers. Some signal blockers may have poor filtering performance, resulting in the generation of interference harmonics or a significant increase in background noise. In such cases, when the listener is in close proximity to the signal blocker, there may be noise interference when receiving the exam content through FM radio broadcasting, which could affect the listening test.

Mitigation Measures:

To ensure the smooth progress of the English listening test, many exam venues choose not to activate signal blockers during the listening test period. Instead, they activate the signal blockers after the listening test is completed. This approach allows for uninterrupted FM radio broadcasting during the listening test, minimizing any potential impact on the exam.


Signal blockers are essential equipment in standardized exam rooms to prevent cheating during CET exams. While theoretically, signal blockers should not interfere with FM radio broadcasting, variations in emission frequencies and poor filtering performance may lead to noise interference during the listening test. To address this concern, exam venues often adopt measures to temporarily disable signal blockers during the listening test period. These measures ensure the smooth progress of the English listening test and minimize any potential impact on FM radio broadcasting.