A system for controlling turning on and off of closed captioning receives information regarding a program content stream and automatically determines whether to turn on or off closed captioning based on thresholds being crossed regarding an estimated current loudness level of ambient noise and an estimated current loudness level of the audio of the program content stream. The estimated current loudness level of audio of the program content stream is, or is based on, one or more indications of current volume level in an audio signal representing the audio of the program content stream and current audio settings of a device outputting the audio of the program content stream. The system may estimate the loudness level of the ambient noise by use of a loudness meter that causes the ambient noise to be sampled with a microphone and a decibel level of the sampled ambient noise to be determined.