Mechanical wave propagation (diffraction / reflection)

In summary, the conversation discusses the propagation of mechanical waves through loudspeaker diaphragms and their similarity to acoustic waves in waveguides. It also considers the source of the mechanical wave in different types of drivers and the possibility of optimizing diaphragm geometry to minimize and distribute energy over a wider bandwidth. The use of corrugations to dampen the edges of diaphragms is also mentioned as a common practice in the industry.
  • #1
thadman
27
0
Excuse me if this question is obvious.

Do mechanical waves propagate through loudspeaker diaphragms (whether they be elastic or rigid) in the same way that acoustic waves propagate through waveguides albeit a different medium? As far as I understand, reflections occur at the boundaries of the diaphragm due to a similar mechanism (an impedance mismatch) in the same way reflections occur at the mouth of a waveguide.

Assuming this is true, where would the source of the mechanical wave occur in a driver where the motor force is distributed uniformly over its surface (ESL/Ribbon) and for a driver whose motor force is not distributed uniformly (Dynamic Cone)?

Could diaphragm geometry be conceived in such a way to optimize its mechanical diffraction / reflection pattern to minimize and distribute the energy over a wider bandwidth?

Thanks,
Thadman
 
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  • #2
thadman said:
Do mechanical waves propagate through loudspeaker diaphragms (whether they be elastic or rigid) in the same way that acoustic waves propagate through waveguides albeit a different medium? As far as I understand, reflections occur at the boundaries of the diaphragm due to a similar mechanism (an impedance mismatch) in the same way reflections occur at the mouth of a waveguide.

All correct so far.

thadman said:
Assuming this is true, where would the source of the mechanical wave occur in a driver where the motor force is distributed uniformly over its surface (ESL/Ribbon)

There is NO wave in this case, at least if the edge is not clamped. If the edge is clamped then it will be a source of a wave of reverse polarity to the original.

thadman said:
and for a driver whose motor force is not distributed uniformly (Dynamic Cone)?

The voice coil / former.

thadman said:
Could diaphragm geometry be conceived in such a way to optimize its mechanical diffraction / reflection pattern to minimize and distribute the energy over a wider bandwidth?

hm ... i think Manger was trying to do something like this ?

Also what is usually done is the edge is damped by corrugations. Most JBL PRO drivers have this.
 

1. What is mechanical wave propagation?

Mechanical wave propagation refers to the movement of a mechanical disturbance or vibration through a medium, such as air, water, or solids. This disturbance causes particles in the medium to move back and forth, transferring energy and creating a wave.

2. What is the difference between diffraction and reflection of mechanical waves?

Diffraction is the bending of a wave around an obstacle or through an opening. Reflection, on the other hand, is the bouncing back of a wave when it encounters a boundary between two different mediums. Both processes involve a change in direction of the wave, but diffraction occurs without a change in medium.

3. How does the wavelength of a wave affect its diffraction and reflection?

The wavelength of a wave plays a crucial role in both diffraction and reflection. When the wavelength is smaller than the size of the obstacle or opening, diffraction is more pronounced. For reflection, the angle of incidence and the wavelength determine the angle of reflection according to the law of reflection.

4. What factors affect the amount of diffraction and reflection of a mechanical wave?

The amount of diffraction and reflection of a mechanical wave is affected by several factors, including the wavelength, the size and shape of the obstacle or opening, and the speed of the wave. The type of medium and the angle of incidence also play a role in both processes.

5. Why is understanding diffraction and reflection important in various fields of science and technology?

Diffraction and reflection of mechanical waves play a crucial role in various fields such as engineering, acoustics, and optics. Understanding these processes helps in designing and improving technologies such as sonar, radar, microscopes, and telescopes. It also allows scientists to study and analyze the behavior of waves and their interactions with different mediums, leading to further advancements in these fields.

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