Hi,
Does anyone have any insights into the linearity of headphone sensitivity as power is reduced? For example, given headphones with a sensitivity of 87db SPL at 1mW, the power that would output 0dB SPL is 0.185pW.
But surely the headphone actuators would stop moving long before that on the grounds that a minimum power would need to be applied to overcome the inertia of the actuator? So I am guessing that sensitivity becomes non-linear at low power levels.
Regards...
Does anyone have any insights into the linearity of headphone sensitivity as power is reduced? For example, given headphones with a sensitivity of 87db SPL at 1mW, the power that would output 0dB SPL is 0.185pW.
But surely the headphone actuators would stop moving long before that on the grounds that a minimum power would need to be applied to overcome the inertia of the actuator? So I am guessing that sensitivity becomes non-linear at low power levels.
Regards...
No.
You are thinking of friction, static friction.
If sensitivity changed with level that would be Distortion. Yes, there is distortion, but at HIGH levels not usually LOW levels.
> You are thinking of friction, static friction.
No I'm not. I'm thinking of inertia. Yes, there will be friction due to the stiffness of the diaphragm but that effect is linear so I'm not concerned with that.
> If sensitivity changed with level that would be Distortion.
At any power level, sensitivity changes with frequency - look at any specification sheet - so you will get distortion for a real-life audio signal. But sensitivity is measured at a single frequency so variation over frequency, and any distortion that accrues, is irrelevant. But I'm not concerned with frequency, I'm concerned with power level. Similarly, if sensitivity changes with power level distortion equally does not apply.
No I'm not. I'm thinking of inertia. Yes, there will be friction due to the stiffness of the diaphragm but that effect is linear so I'm not concerned with that.
> If sensitivity changed with level that would be Distortion.
At any power level, sensitivity changes with frequency - look at any specification sheet - so you will get distortion for a real-life audio signal. But sensitivity is measured at a single frequency so variation over frequency, and any distortion that accrues, is irrelevant. But I'm not concerned with frequency, I'm concerned with power level. Similarly, if sensitivity changes with power level distortion equally does not apply.
Reply to my own post:
Just talked to a physicist and I have it back-to-front. Inertia is linear, friction is non-linear. There would be some minimum initial force required to make the diaphragm move in the first place.
Just talked to a physicist and I have it back-to-front. Inertia is linear, friction is non-linear. There would be some minimum initial force required to make the diaphragm move in the first place.
Static friction is when surfaces rub against each other, a decent transducer design avoids this and only has material components stretching and flexing, which is elastic deformation (possibly with some viscous friction) which are linear and have no lower threshold.