Three studies were conducted to answer the question of why the use of a cell phone in public space is considered rude. The first study focused on what correction should be made to the average decibel (dB) level of a cell phone conversation. The second study took place covertly in a public setting and found that after controlling for certain variables, cell phone users talk (on average) 1.899 dBs louder than two co-present face-to-face individuals having a conversation. The third study built upon previous research that found hearing only one half of the conversation leads to a greater perception of rudeness from the participant. The speaker's volume was also recorded and controlled for. The results of the third study show that when only hearing one side of the conversation, participants rate the speakers as more rude. The amount of time the observers themselves use a cell phone lessens this effect. Results show that the more time spent using a cell phone, the lower the rating of rudeness given to other cell phone users. The increased volume of cell phone users and the effect of only hearing one side of a conversation seems to disrupt the social situation being defined by observers. This leads to a greater perception of rudeness of public cell phone behavior. Cell phone users may be rated as less rude than two people having a co-present face-to-face conversation because of a combination of expectations and the observers own cell phone habits.