Echoic memory is best described as:

Echoic memory is best characterized as a type of sensory memory specifically related to auditory information. This form of memory allows individuals to retain a fleeting impression of sounds, such as spoken words, for a brief period after the auditory stimulus has ended. Typically, echoic memory lasts for about 3 to 4 seconds, which is crucial for understanding language and conversation since it provides a temporal buffer that enables people to process words and sentences as they are heard.

In contrast, the other options describe different aspects of memory that do not pertain to the auditory sensory experience. A memory system for visual images refers to iconic memory, which deals specifically with visual stimuli. Long-term memory encompasses a broader category of memory storage that retains information for extended periods, which echoic memory does not fit into since it operates on a much shorter timescale. Lastly, a method of memory rehearsal pertains to strategies used to enhance memory retention and recall, rather than the initial sensory memory process itself that echoic memory represents.