4

This is one definition I have found for resonance:

the reinforcement or prolongation of sound by reflection from a surface or by the synchronous vibration of a neighboring object.

But I basically thought that's what reverb was, controlling the nature of a sound's artificially simulated environment to control its reflections.

What is the difference?

2

The definition you gave seems to have the definitions for resonance and reverb built into one, which makes it more confusing.

From a physics perspective, everything has various resonant or natural frequencies. Here's a little tidbit if you're interested. These characteristics are known better to musicians as harmonics.

As I learned in physics:

Resonance occurs when a material/object is vibrated at its natural frequency.

This is a unique occurrence which causes something to vibrate. Something else (the origin of the sound) must have vibrated at this same frequency. From the above linked source:

The result of resonance is always a big vibration - that is, a loud sound.

Thus, resonance is a phenomenon which occurs due to the physical properties of a material. So, you could say that resonance emphasizes or reinforces a sound. One example is that buzzing/rattling which happens with loud bass.

Reverb is just what you think it is. It's just the "dying out" or extension of a sound. Like you said:

the...prolongation of sound by reflection from a surface...

Whereas resonance could be defined as

the reinforcement...of sound...by the synchronous vibration of a neighboring object

In the context of sound production, resonance causes certain frequencies to become more prominent in rooms which have those natural frequencies. A large room or hall, etc. will reverberate any sound, though, because the echoes take a long time to die off.

While mixing, the line definitely blurs. You can certainly emulate resonance with EQs and reverberation. And if you're not doing any recording, you really don't need to worry about the difference.

3

Resonance and reverberation are, indeed, more or less just two aspects of the same phenomenon. The difference is whether you focus on what happens to the time-domain representation (reverb) or frequency-domain representation (resonance) of a signal. For instance, when you seed a room with a short impulse and observe how a microphone picks up a far longer sound event, you call it reverb. If you start with white noise and notice the microphone picks up one frequency more strongly than the others, you call it resonance.

However there's a big possible overlap between these two phenomena. In a nearly cubic chamber with stone walls, you get a long reverb to a short impulse – but it will be predominantly a few frequencies sticking out. You might say, the reverb is resonant. Likewise, if you design an electronic filter with particularly sharp resonance characteristics, you'll find it actually “sustains” (you might say, reverbs) the resonant frequencies.

OTOH, a constant-phase EQ changes the frequency spectrum a lot, without really altering the time response notably at all. And an echo chamber has a pretty long reverb, but no frequencies should resonate very strongly.

0

I think of reverberation as occurring inside a space, and resonance to be more object based. So a tuning fork resonates when you strike it, and if that occurs inside a room - then and the sound reverberates around that room.

0

Resonance is when you make something vibrate through the sound. If you scream at an acoustic guitar, the strings will yield a faint sound afterwards. The strings are resonating.

Reverb is a sound bouncing around inside a room.

The phenomena are related, for example, a room with parallel walls will have sound bouncing back and forth between those walls, and this will cause resonance, making the room "ring" at certain resonant frequencies.

0

I think I am sitting in a room by Alvin Lucier really captures the difference between reverberation and resonance. Objects, including rooms, have resonant frequencies where there is essentially no damping.

When you pluck a guitar string, you excite it with all (many) frequencies. The vast majority of the frequencies die out quickly and you are left with the resonant frequencies. When you clap your hands in a room, you are exciting it with all frequencies. In a dead room all the frequencies die out quickly. In a live room, the sound takes multiple seconds to die out. The frequencies that die out the slowest, are the resonant frequencies.

  • I'm sorry, but in the context of this answer as written I still don't see what turning resonance up or down would do, what metric is being changed. – temporary_user_name Jun 1 '15 at 15:31
0

I think you were actually asking a physics question but... If you're referring to the resonance knob on a filter - it increases the amplitude of the frequencies within some small range of the cutoff point. Also referred to as Q-value.

0

Your definition is correct, let me explain:

"the reinforcement or prolongation of sound by reflection from a surface..."

  • a xylophone / vibraphone. When you thunk it with the mallet / hammer the bar resonates at its natural frequency. Each bar is tuned to a different natural frequency.
  • when you press a key on a piano, nearby strings belonging to different keys may resonate in harmony.
  • when a violin is bowed, the case resonates in sympathy amplifying the sound. The case acts as a filter, different materials / shapes (and a whole host of other factors) cause the case to vibrate differently thus producing a different tone. This tone is made by resonances. Each note will cause the body to vibrate differently, and the various harmonics of the notes will be louder / quieter depending on the body's response.

"... or by the synchronous vibration of a neighboring object."

  • Now this is interesting. Very interesting. Neigbouring objects can resonate in harmony with each other, despite not being excited directly. The classic example is that of an opera singer shattering a glass because the opera singer is producing a note (or, more correctly a frequency) which excites the glass to vibrate naturally. If the amplitude from the singer is enough, it could cause the glass to vibrate beyond its elasticity allows and break. Once a "natural frequency" of an item is excited, if continued the internal vibrations in the item will continue to get bigger and bigger and bigger. Imagine swinging a rope which is tied to each end. If you time it right, with the minimum of force you can make it swing bigger loops just by a gentle twiddle at the right time. This is akin to the natural frequency.
  • Also, there are experiments where you can place two pieces of tuned wood about 1M apart, hit one piece of wood, and the other one will start resonating in sympathy.

Reverberation

Goose quacks echo, but apparently duck's don't! - Have you ever played those games where a laser shoots out, and you have to use mirrors to get the laser where you want it to score points / move onto the next level? Well, imagine the laser is the sound wave, and the mirrors are walls, people, anything. Sometimes the sound wave will be absorbed by things (that's why the weaker higher frequencies sound fine in an empty theatre, but totally vanish when it's a full-house). And, sometimes, it will bounce off shooting off in another direction. Each bounce causes a dissipation of energy though (unlike those games where the light doesn't get weaker), so the sound becomes weaker and weaker and weaker.

So, in a large environment, think a cathedral, that's why you can get large gaps between reverberation hits which you can hear, and in something smaller like a box bedroom, you hear a shorter "boxier" sound.

The really fun part is when the waves that bounce off walls and objects then smash into each other making them louder / weaker and changing the acoustics of the environment (standing waves).

Hit a basic acoustics book for more.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.