I'm still not understanding concept of resonance being applied to every frequency response aberration in a speaker:
In sound applications, a resonant frequency is a natural frequency of vibration determined by the physical parameters of the vibrating object. This same basic idea of physically determined natural frequencies applies throughout physics in mechanics, electricity and magnetism, and even throughout the realm of modern physics. Some of the implications of resonant frequencies are:
1. It is easy to get an object to vibrate at its resonant frequencies, hard to get it to vibrate at other frequencies.Example
2. A vibrating object will pick out its resonant frequencies from a complex excitation and vibrate at those frequencies, essentially "filtering out" other frequencies present in the excitation.Example
3. Most vibrating objects have multiple resonant frequencies.
As I understand that definition, a "natural resonant frequency" is tied to the physical parameters of the speaker, (size, mass, volume, internal bracing, etc.) It doesn't say that external influences that cause the speaker to oscillate at frequencies other than its natural frequencies
are considered resonances.
likes to use the example of blowing across the top of a bottle as example of resonance. When you blow across the top of the bottle, the air inside the bottle will resonate at its natural frequency. If you add some water to the bottle, you change the volume of the chamber and therefore the natural resonant frequency:
Adding water to the bottle is a change to a physical property of the system, and that changes the natural oscillating frequency or the resonant frequency.
I guess what I'm still having trouble understanding is, if the natural resonant frequency is tied to mass or volume, how does externally/electronically adding a rise in the response in a certain bandwidth change the natural oscillating frequency? How does an external electrical adjustment, (i.e., something done in a crossover), change any physical
parameter of the speaker, or change it's *natural*
frequency of oscillation? It can certainly change the levels at which the driver oscillates in a certain frequency band, but it doesn't change any of the inherent physical attributes of the speaker. Moreover, the frequency band of the external adjustment does not even consider any natural oscillating frequency of anything in the system. It's simply a choice made by a design engineer. Since frequencies other than the natural oscillating frequency are harder to make oscillate, it seems counter-intuitive to call an externally induced oscillation a resonance.
The definition of resonance being used here excludes the concept of the "natural resonant frequency" and replaces it with any oscillating frequency. If this is the way the term resonance is used, and that usage is what is used to define neutrality of a speaker, I will readjust my thinking, even if it doesn't match the definitions I've always used.
Having said that, I think it would be more clear to use the definitions as they've generally been used, because I think many/most forum members were and are using those terms in that way. The only time I've ever encountered someone calling a designer induced mid-bass hump, (or any other external FR change), a "resonance" has been in this thread.