When I use esp8266 as STATION mode and connect a speaker between VCC(3.3v) and GND pin a sound appears like "doop doop". what is this sound? I test this in version 01 and 12 of esp8266 module and this appear in both versions. maybe you ask me why I connect speaker to this pins. problem is that when I use pwm of esp8266 for playing a sound, this sound ("doop doop") appear to it also. What is problem? How can I fix this?