It is good Netiquette to use earphones for audio. Don't play audio without headphones.
Smartphones are personal devices not public media players. Audio can be heard by the people around. This distracts people for various reasons and to various degrees. Earphones prevent others from hearing the audio from a smartphone.
Streaming personal audio and video from the Internet can distract others. Earphones make personal streams more personal because you are the only person that can hear it.
Use earphones for media because audio is distracting.
Published on May 16, 2015 | 0:38 Seconds | Science and Technology
An introduction to Smartphone Netiquette. Keywords, graphics, and symbols.
Published on February 14, 2012 | 1:12 Minutes | Science and Technology
The Rules of Smartphone Netiquette by David Chiles from a planet in the Cell Phone Cybershphere.