Final answer:
Studies show that an average person may remember approximately 50% of what they hear shortly after learning it, but this retention decreases substantially with time.
Step-by-step explanation:
Studies suggest that people may remember varying amounts of what they hear, but a common finding is that an average person will retain approximately 50% of the memorized information after a short period such as 20 minutes. Over time, this retention drops significantly, and after 24 hours, approximately 70% of the information is lost, according to Hermann Ebbinghaus's famous forgetting curve. In the context of short-term memory, however, George Miller's research pointed out that individuals could remember between 5 and 9 pieces of information, famously coining this capacity as the "magic number 7 plus or minus 2". Recent studies have slightly adjusted this number to 4 plus or minus 1 for our working memory capacity. Acoustic encoding, which involves auditory information, typically results in better recall than visual encoding.