The hypodermic needle theory suggests that media messages are directly absorbed by a passive audience, impacting everyone uniformly. It posits that audiences uncritically accept media without engaging mentally. Music is cited as exemplifying this theory since it can be consumed passively. Advertisers leverage the theory by using music to make ads, films, and products more memorable through repeated exposure. The author plans to apply the theory in their magazine by including light, undemanding content that doesn't require critical thought.