Nissin MG10 Wireless Flash with Air 10s Commander (Nikon) - Manual (Page 21)

Hold button to switch the buzzer (on strobes) on or off.
When “no buzzer” logo is displayed in LCD, it means that the beep sound is off.
When the “no buzzer” logo disappears, then the buzzer function is turned on.
20
Buzz (Beep sound) on strobes
All settings of strobes are controlled by the commander wirelessly after the pairing
is completed. If the strobes buzzer is on, a “Beep” sound will be heard when the
Strobe is charging and not ready to flash. The “Beep” sound will be heard everytime
when there is any change made through the commander.
Air 10s Beep or Buzzer on & off switch