LuckyNat
500+ Head-Fier
- Joined
- May 23, 2015
- Posts
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- 117
This is how I understand it, using a couple of pictures from the web (which are not necessarily to do with driver asymmetry but actually effects of some filters on processed audio causing waveform asymmetry - same graphic representation though) :
This is the waveform of your audio. When it is replayed by a driver, then lets say positive amplitude is the forward movement of the driver and negative backwards movement. In free air, a driver diaphragm will move kind of evenly about the baseline. That's a simplification for sake of explanation (some drivers will be asymmetric in their movement anyway due to design).
When you have uneven pressures either side of the driver diaphragm like in a headphone or speaker, it is going to be able to move more into the lower pressure area whilst the higher presure side will dampen its movement. So then you end up with an asymmetric waveform which look like this:
See how it moves more into the positive than the negative.
Now, from what I understand, this doesn't have much effect when it's an electrical waveform on your computer screen. BUT Davies is saying it has a BIG effect when it's turned into real air pressure wave asymmetry hitting your ear drum.
Your ear drum is pushed more in one direction than the other, a net pressure in one direction - that's not what free-air natural sound does, sounds like distortion to the ear, causes listening fatigue and also brings you closer to hearing damage. Thinking about it, looking at the picture, it will cause your ear drum to move in one direction as if getting battered by a loud sound whilst the average loudness remains apparently fine and comfortable..
That's the basis of the theory as I understand it. With a sealed iem especially and any headphone I guess with air pressures up against your ear, it's going to be more of a problem.
This is the waveform of your audio. When it is replayed by a driver, then lets say positive amplitude is the forward movement of the driver and negative backwards movement. In free air, a driver diaphragm will move kind of evenly about the baseline. That's a simplification for sake of explanation (some drivers will be asymmetric in their movement anyway due to design).
When you have uneven pressures either side of the driver diaphragm like in a headphone or speaker, it is going to be able to move more into the lower pressure area whilst the higher presure side will dampen its movement. So then you end up with an asymmetric waveform which look like this:
See how it moves more into the positive than the negative.
Now, from what I understand, this doesn't have much effect when it's an electrical waveform on your computer screen. BUT Davies is saying it has a BIG effect when it's turned into real air pressure wave asymmetry hitting your ear drum.
Your ear drum is pushed more in one direction than the other, a net pressure in one direction - that's not what free-air natural sound does, sounds like distortion to the ear, causes listening fatigue and also brings you closer to hearing damage. Thinking about it, looking at the picture, it will cause your ear drum to move in one direction as if getting battered by a loud sound whilst the average loudness remains apparently fine and comfortable..
That's the basis of the theory as I understand it. With a sealed iem especially and any headphone I guess with air pressures up against your ear, it's going to be more of a problem.
