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In Reply to: RE: The elephant in the room is... posted by Duke on August 24, 2014 at 13:56:14
I've heard this logic before:
" The ear/brain system does not even detect the presence of bass energy from less than one wavelength. At low frequencies, the wavelengths are so long that they've encountered one or more room surfaces by the time we even begin to detect them (and it takes several wavelengths before we can hear the pitch, by which time the room is even more deeply involved). So in most home listening rooms, we literally cannot hear the low bass apart from the room."
How do headphones reproduce bass with such a small distance between driver and eardrum?
Follow Ups:
"How do headphones reproduce bass with such a small distance between driver and eardrum?"I hope it doesn't sound like I'm saying rooms can't support bass energy because their dimensions are less than one wavelength. If so, please tell me what I said that gave that impression, so I can reword it.
What I'm talking about in the paragraph you quoted is that it takes some time before the ear/brain system registers bass energy (how much time depends on the wavelengths), and by the time that happens, those long wavelengths have bounced around the room somewhat (assuming typical home listening room sizes). So you inevitably hear the room's effect on the speaker(s) bass output because your ears can't process the bass energy quickly enough to avoid the room's effects.
To answer your question, the ears register and hear the pressure of the bass energy against the eardrum whether the "room" is a headphone or a football stadium.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 08/24/14 08/24/14 08/24/14
So if you have a pair of headphones that has good bass, you should be able to detect room problems when comparing them the sound of you speakers. I think I am going to give that a try, since I recently picked up a pair of Sennheiser HD555 headphones that have very good bass. Thanks!Dave
Edits: 08/28/14
"So if you have a pair of headphones that has good base, you should be able to detect room problems when comparing them the sound of you speakers."
I'm not sure even good headphones are a reliable reference for bass quality. In the recording studio, headphones are notorious for NOT allowing the engineer to set the levels of the bass instruments properly.
I speculate that not only is the tactile aspect of bass necessary for reference quality, but also that the inherently slower decay of bass energy in a room may contribute to pitch differentiation. Obviously we don't want the decay to be too slow, but headphones may go too far the other way.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
So you saying that headphones are not the ultimate reference because you would erroneously perceive the pitch of an anomaly due to the slower decay of bass energy in a room. I will keep that in mind when I compare. That given, headphones still could be useful in detecting the presence of an anomaly even if there are inaccuracies in its presentation. Of course how a room sounds can ultimately only be judged by how it sounds. I was looking at purchasing a sound level meter, but that has its problems too. It appears there is no simple solution.
Dave
Where pitch and timbre are concerned you can't hear it in the true sub bass frequencies, ie., below 35Hz. That information comes from the bass and higher frequencies. It's not easy to test that out, as you need not only the usual sine wave generator etc. but also speakers capable of both high output and extremely low THD, otherwise what you're hearing when you play a 25Hz tone and you can discern pitch is harmonics. But if you have horn loaded subs with an Fc of 30Hz or lower you can test them in your backyard and distinctly hear where the sound transforms from indistinguishable rumble to actual pitch, in the 35-40Hz region. It's just as enlightening to play 15Hz at 100dB and not hear a thing, with only the reading of the meter telling you that the sound is there.
By the same token chances are you can't find phones with low enough THD below 35Hz at a high enough output level to hear only the fundamental and not harmonics as well.
It took me a while to digest this, before I could comment. I think you are saying inside a normal room all you will hear is ruble below 35Hz. With headphones, you will have the same result, but it is from THD. So the headphone comparison is only valid above 35hz. Interesting what you say about a horn sub outdoors. Someday I should order the plans and build a Tuba ...
Dave
> I think you are saying inside a normal room all you will hear is ruble below 35Hz.
Yep. It doesn't seem that way, but only because it is an exceedingly rare situation where you'd have frequencies lower than 35Hz with no accompanying harmonics providing pitch and timbre information.
A big ten-four on that!
If "audiophiles" would actually open a book (not to be confused with a magazine or brochure) and learn about the harmonic structure of various instruments, they'd learn that most of what they're hearing when they listen to the very low tones on, say, a tuba or bass violin (string bass) or pipe organ, are the first couple of overtones, not the fundamental. The first overtone (second harmonic) is almost always at a much higher level than the fundamental.
This is one of the reasons why I keep recommending Harry Olson's "Music, Physics and Engineering". It's a treasure trove of knowledge needed to gain a basic understanding of sound, musical instrument sound characteristics, how sound behaves in rooms, and more.
:)
Some of us who listen to headphones on a regular basis in the home environment think that you are correct, and some of us who use "open-backed" headphones might go so far as to employ the use of a subwoofer. Seems like a weird idea at first, but those who have tried it know about that sense of viscerality and that slightly more natural sense of LF "decay".
Edits: 08/26/14 08/26/14 08/27/14
I agree with you, except for the part about a subwoofer seeming a little weird. ;) Our bodies are pretty sensitive to low frequency sound, so there's a good reason why headphone listening can be improved by using a subwoofer (or, as I like to call it, a woofer).
On the other hand, I find headphone listening to be very unnatural - regardless of the recording technique, and only do it when I'm making a recording and need to monitor the sound, or at home when other people want to get some sleep!
:)
Headphones listening is something of an "acquired taste", I think. But it must be admitted that more and more people are acquiring headphones and that this trend will most likely continue on for quite some time. I hope that more people will learn how to make the most of their headphone listening experience.
"that has good base,"
"HD555 headphones that have very good base."
Credibility immediately goes out the window when one can't even spell the word which is the topic of the discussion.
Thank you for the correction. I have edited the post. Unfortunately there are some words that I routinely mistype. As long as the mistype is a real word, spellcheck won't detect it.
Dave
Funny...when I typed spellcheck in the subject line as a single word spell check detected it for me, just as it has again in this sentence.
Yeah, if I remember correctly, at mid frequencies, say 500 or 1000 Hz, it takes about three cycles to perceive the pitch of a tone. Shorter durations are merely perceived as a "click".
Now I've got to go find that, to make sure I've got it right. It's in a book around here somewhere.
:)
> How do headphones reproduce bass with such a small distance between driver and eardrum?
+1. The theory of 'wave propagation' is total myth. It's source is a real effect, boundary cancellations, where the combination of speaker, boundary and listener position can cause low frequencies to be highly attenuated close to the speaker, but not attenuated further away. Laymen with no understanding of phase and boundary reflections came up with the notion that one had to be a certain distance away from a source to hear it. It's nonsense.
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