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aknudskov t1_j5qy47h wrote

This measures how fast a membrane moves in response to a signal, right?


blargh4 t1_j5r11n4 wrote

Well, moreso how the sound decays. You stimulate the driver with a very short electrical pulse, and see how it responds and how fast different frequencies decay.


aknudskov t1_j5r1s62 wrote

Yeah that is where I was going with it at first but I guess the first part shows the initial response too. Interesting. I would say this implies to show how fast/responsive a speaker is. I wager a planar magnetic would have a much tighter graph than an hd-600 as an example. Something that sounds "muddy" would have a much longer timeframe shown right ?


FastGecko5 t1_j5r7f2n wrote

Isn't "mud" as we usually talk about it a product of the frequency response? Namely too much boost in the 200-500Hz range


aknudskov t1_j5r9k9n wrote

I always thought it was the membrane vibrating too long /shrug


audioen t1_j5srj6c wrote

I answered earlier to OP directly at top-level comment, but I want to answer this one directly. The impulse response is the same thing as the frequency response, it is just time-domain characterization of the system, whereas frequency response is the frequency domain equivalent, though we are usually not shown the complex number nature of the frequency spectrum where phase information of the sound is encoded because we do not hear phase directly and the phase plot doesn't relate to anything we can intuitively understand.

If the speaker membrane moves slowly back to neutral position after an impulse has excited it, that would show up as a decaying plot, and in frequency response would look like a low-pass filter. One way to understand it is to think that system isn't fast enough to reproduce waveform that cycles in and out of phase within that decay region, so if the wavelength is short relative to the impulse's decay time, it cancels with prior versions of itself that are decaying in the impulse, resulting in little output.

In this case, the impulse drops gradually rather than instantly, suggesting that there is some low-pass filtering effect, but also overshoots and goes below zero, which suggest to me that it has could have high pass filtering characteristic, too. For low frequencies, whose wavelength is long relative to the impulse, the negative parts of the impulse subtract from the positive side, and reduce output for low frequency. The fact impulse also returns to the positive side suggests it also contains a resonating component, though. If wavelength is the same as the impulse's ringing around zero level, then it will be amplified by the impulse response.

Finally, if impulse response is ideal, and system's frequency response is perfectly flat, and phase is linear, the entire impulse response is just a single spike with perfect silence surrounding it forever. The ideal impulse indicates that whatever the signal wants to do, the system can reproduce without altering it.


SupOrSalad t1_j5rc0mt wrote


lr_science t1_j5sor2a wrote

interesting article, but for some reason it stops right before the point where I would EQ the cheap cans to bring back the frequencies they’re lacking. isn’t it the most obvious next step to do this and see if that makes them sound faster? and then the next question would be: do all headphones sound identical once the FR is equalized between them? my guess would be no, and the next question is what measurements or graphs would explain the remaining differences.


Titouan_Charles t1_j5sja2p wrote

The membrane will only vibrate at the speed of the signal it is given, so a Planar will replay 1000Hz the same way a dynamic Wil lvibrate 1000Hz. They both play the same source. What we can observe here are the decay, reflections, resonances involved with the headphon'es design (closed back, ported back, good seal/sound leak from the pads, etc) and this affects the sound signature significantly.