Camera Flash Pop Sound: What Causes It?

[CodyW]

Hi everyone,

I was wondering if anyone knew what causes the popping sound when an external camera flash is fired?

Kind regards
Cody

 

[Drakkith]

An interesting question. I found several possibly answers here: http://forums.anandtech.com/showthread.php?t=2014008

In particular, it seems that the charging/discharging of the circuit elements creates mechanical vibrations which can manifest as pops, whistles, and hums.

 

[CodyW]

The whistling / high pitch noise when the camera flash is charging up is caused by magnetostriction on the inductor of the flyback converter in the flashes circuitry. I think possibly the LC resonance may play a part as well. :)

The pop sound when the flash is fired, I've noticed, gets louder as I put my hand up close to the end of the flash. Would it have something to do with the energy coming out of the flash?

Sorry for the poorly written post. I've had close to no sleep haha.

 

[TumblingDice]

I don't know how far of a parallel can be drawn, but reading wiki articles for both flashtubes and thunder, each mention supersonic shock waves related to rapid thermal expansion of plasma produced by the electric arc.

Flashtube: http://en.wikipedia.org/wiki/Flashtube
Thunder: http://en.wikipedia.org/wiki/Thunder

Flashtube:

Flashtubes produce an electrical arc flash contained in a glass tube. As the arc develops a supersonic shock-wave forms, traveling radially from the center of the arc and impacting the inner wall of the tube.

Thunder:

In the 20th century a consensus evolved that thunder must begin with a shock wave in the air due to the sudden thermal expansion of the plasma in the lightning channel.