1. Device setting problem: First, check whether the audio setting of the monitoring device is correct. Some monitoring devices may have the option to mute or turn off audio, so it is necessary to confirm whether the audio function is enabled.

2. Audio line failure: If the wired monitoring system is used, audio line failure may occur. Check whether the audio cable is firmly connected, and eliminate the possibility of cable loosening or damage.

3. Device compatibility: Some monitoring devices may not be compatible with specific audio formats or codecs. Make sure the listening device supports the audio format you are using, or try to test with another audio format.

4. Software setting problem: If you watch monitoring through mobile phone or computer software, check whether the audio option in the software setting is turned on. Sometimes the audio function may be turned off by default and need to be turned on manually.

5. Network bandwidth limitation: If you watch the monitoring through the network connection, the low network bandwidth may lead to the abnormal transmission of audio. Make sure your network connection is stable, and try to test through other network environments.

Extended content:

In addition, if the above solutions have no effect, we can also consider the following situations: whether the audio function of monitoring equipment is damaged, whether it needs to be repaired or replaced; Whether other devices or software conflict with the monitoring device, resulting in abnormal audio transmission; Or the audio function of the monitoring equipment itself is unstable, and it is necessary to upgrade or replace more reliable equipment.

In a word, to solve the problem of no sound in monitoring equipment, it is necessary to investigate the possible causes one by one and make corresponding adjustments and maintenance according to the specific situation.