Joe Bryan wrote on Tue, 01 March 2005 05:54 |
Hi Dan-
I'm not quite ready to accept your assumption that the ear has the band-limited reponse your argument requires.
I'm not an expert on human perceptual physiology, so I'll leave this point for others to debate. However, I know how circuits behave, and if the physical issues I've mentioned have analogues in our hearing system, I wouldn't be very surprised.
In the mean time, I'll continue to believe my own ears when it comes to audio quality issues.
Cheers,
-Joe
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Hi Dan-
I'm not quite ready to accept your assumption that the ear has the band-limited response your argument requires.
I'm not an expert on human perceptual physiology, so I'll leave this point for others to debate. However, I know how circuits behave, and if the physical issues I've mentioned have analogues in our hearing system, I wouldn't be very surprised.
Cheers,
-Joe
Your statement is that you understand circuits, therefore it gives you a sense of the mechanics is less that half baked. You just claimed some knowledge and left it at that, no explanations, and I think your statement actually helps “my case”.
I too know about circuits, and IF the physical issues you mentioned are indeed analogues to hearing system, that only makes my statement more correct! I do not know if that ear is behaving like a circuit, and making such assumption is going very far in my book. But microphones, speakers and dynamic mechanical systems have been modeled by electrical circuits, such as in the era of analog computers. I believe there was a time when automotive suspension was modeled by electrical means…
Let me state some of the principles that make such analogy work:
A network of electrical circuit made of R,L and C is an expression of the relationship between voltage and current flow over time where:
Resistance relation of curent to voltage is proportional
Inductance has to do with rate of change in current
Capacitance relates to to voltage by accumulation (integration).
We can interconnect those elements in any configuration we wish, and it all boils down integral-differential equations for the circuit behavior, all with respect to time.
Now let us take a mechanical system. Making the ratio between distance of the motion over time (velocity) is analogous to electrical current
The mechanical spring action behaves like an electrical capacitor.
The mass is relates to the derivative of velocity, acting like inductance.
The damping (such as viscous friction) is a derivative function (like electrical resistance).
And before you raise objections, all non linearity, gain and other factors can be modeled by electrical circuits. It is a difficult job, but electrical theory is under the same “bigger umbrella” of the “principles of nature”.
So in fact, the concepts of poles and zeros are not limited to electrical systems. It is more common to talk about poles, zeros, resonance, bandwidth and more in the area of electronics. But the fact is that microphones and speakers also have poles and zeros, and so do relays and motors… If a microphone has say a 3dB mechanical attenuation at 20KHz (the membrane material and air around it does not alow response to such fast variations), it also has a phase shift associated with that attenuation. A dynamic mechanical system is not unlike an electrical one!
In my view, anyone that does understand circuits and signals is in a position to see how steady state mechanics IS VERY MUCH CONNECTED to transient response. Why are you viewing them as 2 seperate worlds?
Let us forget about mass, spring coefficients and chock absorbers. Understanding of analog circuits requires knowledge of the strong connection between transient and steady state behavior! An impulse response is an expression of the bandwidth!!! Given the bandwidth, your staedy state response is limited.
And Vica versa!!! Given a bandwidth, the impulse response is cast in stone! Lower bandwidth sets a limit ob impulse speed (maximum rate of change)!!!
This is true for electrical systems, and for dynamic mechanical systems. Is it true for the ear? I do not know.
But since you wish to connect the ear to electrical systems, your “circuit understanding” should immediately put you in my camp!
Regarding your last comment:
In the mean time, I'll continue to believe my own ears when it comes to audio quality issues., I really do not see how it ties in to this thread.
Regards
Dan Lavry
www.lavryengineering.com