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blargh4 t1_j5r11n4 wrote

Reply to comment by aknudskov in what information an impulse response graph provides about headphones? by MEGA_AEOIU792

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.

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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 ?

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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

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aknudskov t1_j5r9k9n wrote

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

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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.

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SupOrSalad t1_j5rc0mt wrote

This is a good article on the topic https://www.soundstagesolo.com/index.php/features/313-is-it-possible-for-headphones-to-sound-fast-or-slow

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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.

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