* Server logs: Most Internet radio stations use a web server to stream their audio content. The web server logs all of the requests that it receives, and this information can be used to track the number of listeners.
* Streaming media software: The software that is used to stream the audio content can also be used to track the number of listeners. This software typically has built-in features for tracking the number of concurrent listeners, the total number of listeners over time, and the average listening time.
* Third-party services: There are a number of third-party services that can be used to track the number of listeners to an Internet radio station. These services typically provide more detailed information than what is available from server logs or streaming media software, such as the location of listeners and the devices they are using.
The specific method that an Internet radio station uses to monitor the number of listeners will depend on the station's budget and technical expertise. However, all of the methods described above can be used to get an accurate estimate of the number of people who are listening to an Internet radio station.