Which type of recording device captures snoring and other ambient sounds in the sleep study environment?

The microphone is the device specifically designed to capture snoring and other ambient sounds in the sleep study environment. In polysomnography, recording these sounds is crucial because they can provide insight into the patient's sleep quality and possible sleep disorders such as obstructive sleep apnea, which is often associated with snoring.

Microphones are sensitive audio recording tools that can pick up a wide range of sounds, making them ideal for documenting vocalizations during sleep, unlike the other choices. An electrocardiogram is used to measure the electrical activity of the heart, a video camera captures visual data rather than audio, and an actigraphy monitor primarily tracks movement patterns during sleep. None of these alternatives focus on sound capture, which is why the microphone is the correct answer for this task.