Can someone please explain why 'the bass' sounds better further away

[gjones]

[quote name='TimR' timestamp='1371342524' post='2112849']
But what does that have to do with anything. That's only relevant in a standing wave and just means that there will be nodes when the room is a multiple of whole, half, quater, etcl number of wavelengths long.

It has much more to do with room size and where you're standing than just being further away from your cab.
[/quote]

It would work if you were in a field or in the desert.

EDIT: on a windless day.

Edited June 16, 2013 by gjones

[TimR]

[quote name='gjones' timestamp='1371345856' post='2112854']


It would work if you were in a field or in the desert.

EDIT: on a windless day.
[/quote]

No. It is important to understand the nature of longitudinal waves and what the 'sine wave' represents.

First on a google search presents a very good explanation of a free sound wave.

http://www.physicsclassroom.com/Class/sound/u11l1c.cfm

[bremen]

[quote name='gjones' timestamp='1371331625' post='2112741']


[color=#282828][font=helvetica, arial, sans-serif]I was told by a sound engineer that because bass frequency sound waves are so long (measured in metres rather than centimetres), that they have to be further away from the speaker before they form fully and you can hear them correctly.[/font][/color]

[color=#282828][font=helvetica, arial, sans-serif]Nice webpage with diagrams so you can envision the sonic waves doing their thing,[/font][/color]

[url="http://hyperphysics.phy-astr.gsu.edu/hbase/sound/diffrac.html"]http://hyperphysics....nd/diffrac.html[/url]
[/quote]

If this is true*, how come bass sounds so good in headphones, where the source is just a couple of centimetres from the eardrum?

* it isn't. Where's Bill when we need him?

[discreet]

[quote name='bremen' timestamp='1371392087' post='2113248']
Where's Bill when we need him?[/quote]

I'm reasonably sure he will tell you that it's down to The Boundary Effect.
[url="http://www.soundonsound.com/sos/1995_articles/dec95/boundaryeffect.html"]http://www.soundonso...daryeffect.html[/url]

Edited June 16, 2013 by discreet

[TimR]

[quote name='bremen' timestamp='1371392087' post='2113248']


If this is true*, how come bass sounds so good in headphones, where the source is just a couple of centimetres from the eardrum?

* it isn't. Where's Bill when we need him?
[/quote]

Psycoacoustics also plays a part. The headphones don't actually produce the lowest frequencies. Your brain just makes it up because you hear the higher harmonics 2xf 3xf etc. so you know the fundamental should be present. It's known as the missing fundamental.

[Beer of the Bass]

[quote name='bremen' timestamp='1371392087' post='2113248']
* it isn't. Where's Bill when we need him?
[/quote]

I don't think I've ever seen him post outside the Amps & Cabs section, so he may not have seen this thread.

[gjones]

I once told a guitarist that sound engineers find bass much more complicated and difficult to get a good sound with than guitar. He just looked at me and laughed.

[lurksalot]

[quote name='TimR' timestamp='1371403824' post='2113436']
Psycoacoustics also plays a part. The headphones don't actually produce the lowest frequencies. Your brain just makes it up because you hear the higher harmonics 2xf 3xf etc. so you know the fundamental should be present. It's known as the missing fundamental.
[/quote]

I never really thought about that , and i had been using headphones for mixing. I reckon distance is irrelevant if the production of the music (and the bass part of it,or only the bass) is apprecited in a suitable listening environment

[51m0n]

[quote name='iconic' timestamp='1371223439' post='2111425']
I'm not stupid, many may argue that statement but I've got letters behind my name should I choose to use them (I think and they don't all end in T?) I'm a member of the Institute of Mechanical Engineers don't ya know.....which means I can go and sit in the library at Birdcage Walk should I take the fancy but....

.....near field, far field, 'inside the wavelength'....it's all very conflicting, the fact remains it [u][i][b]does[/b][/i][/u] sound better a few feet away than in front of the speaker.....but can anyone explain the reasoning, in simple speak to a dumbass like myself.....acoustics wasn't on the sylabus at college for a mech' eng'.

thanks in advance.
[/quote]

It's exactly the same with all sound sources. If you are within the near field distance then the various parts of the source: ie on a DB the entire body becomes various parts the produce different aspects of the total sound, on a bass speaker the tweeter the port and the driver(s) are acting as single point sources to the mic. Each one produces a part of the sound and getting the mic in exactly the right place to recreate the balance of the sources together as heard from outside the near field distance is almost imporssible to do exactly.

This is being confused slightly with Critical Distance. This is the distance away from the source where the reverb level from the surrounding space equals the level from the source. In other words the amount od sound reaching the microphone having bounced off the boundaries to the space you are in is the same as the amount of sound reaching the microphone directly from the source. In almost aqll cases this sounds like poop in a recording.

If you are using an omni mic you shouldnt get further away than 1/3 of the critical distance, a cardiod mic changes this to about 1/2 of the critical distance.

In the same way audience beyond half the critical distance in a room experience the sound of a band quite differently from audience within this area, any concept of stereo from the band is so muddied by reflection as to be worthless, and unless the room has a short and very even RT-60 they wont hear bass in a tight and refined way. Hint, you arent playing somewhere with a short and even RT-60 time (time taken for the reverb to die down by 60dB if you are wondering) - unless you are in a seriously properly treated studio live room. In fact most venues have a pretty pants critical distance too since they have no absorption other than meat, and that is a very variable and uncontrolled absorption methoid at best
.

[bremen]

[quote name='TimR' timestamp='1371403824' post='2113436']


Psycoacoustics also plays a part. The headphones don't actually produce the lowest frequencies. Your brain just makes it up because you hear the higher harmonics 2xf 3xf etc. so you know the fundamental should be present. It's known as the missing fundamental.
[/quote]

Headphones certainly do produce the lowest octave, mine do anyway! Sealed circumaural phones go down virtually to dc if you shave your head :-)

[TimR]

[quote name='bremen' timestamp='1371472278' post='2114194']


Headphones certainly do produce the lowest octave, mine do anyway! Sealed circumaural phones go down virtually to dc if you shave your head :-)
[/quote]

Manufacturers quote silly figures. Sennheiser say their pro 330s go down to 8hz. In reality the 3dB point is closer to 110, which is already half volume at low A. Your brain is very clever at putting in the things you know should be there but you can't detect.

Edited June 17, 2013 by TimR

[51m0n]

[quote name='TimR' timestamp='1371479021' post='2114320']
Manufacturers quote silly figures. Sennheiser say their pro 330s go down to 8hz. In reality the 3dB point is closer to 110, which is already half volume at low A. Your brain is very clever at putting in the things you know should be there but you can't detect.
[/quote]

Errr, I can tell the difference between something below 110Hz being there and not, my brain is pretty good at doing that, has been fo r agood while now, there is no reason whatsoever to believe headphones dont put out that bottom octave. I have, let me see, three pairs of headphones that categorically do, a pair of Sennheiser HD575 a pair of Studiospares M1000 and some RCA earbuds. They really do put out the low octave, all are different but none of them are 3dB or more light below 110Hz.

Edited June 23, 2013 by 51m0n

[stevie]

There's a simple explanation. 51mon is on the right track.

When you are close to your speaker you are standing off-axis and you only hear part of your sound: you do not hear the higher frequencies because the dispersion pattern narrows at higher frequencies. Go a few metres from your cab and you hear more HF because you are not so far off-axis. In other words, high frequencies beam and you have to be in the beam to hear them. Importantly, higher frequencies are responsible for the definition of your sound.

Once you get further away, what you hear is a combination of direct and indirect sound. The further back you go, the more indirect sound you hear until you arrive at a position where what you are hearing is virtually all indirect sound (bounced off from the walls, ceilings, etc.). Because the off-axis output of a general purpose bass cab rolls off above 1000Hz, its 'power response' or reverberant field response contains very little information above that frequency. Its sound will therefore change in the far field and will become muddy. Yes, that's you (unless you're going through the PA).

This is one of the key arguments in favour of using a small diameter midrange driver (or horn loading) to improve the off-axis response. Either that, or go through the PA, which is likely to have been designed with a useful power response.

[bremen]

[quote name='TimR' timestamp='1371479021' post='2114320']
Manufacturers quote silly figures. Sennheiser say their pro 330s go down to 8hz. In reality the 3dB point is closer to 110, which is already half volume at low A. Your brain is very clever at putting in the things you know should be there but you can't detect.
[/quote]

51mon and I can tell the difference between 40Hz and 80.

So can you. Try sticking a 110Hz high pass filter on while listening on headphones (or half-decent speakers).

[TimR]

The bass will sound better in good headphones due to the proximity effect. They don't need to be powerful in the low range like speakers do.

If your headphones can produce the low end, and I'm only suggesting there are many that don't produce high volumes at low frequencies, many do, then your brain will fill in the missing bits and the proximity effect will take care of the lower volume.

[bremen]

[quote name='TimR' timestamp='1372012077' post='2120656']
The bass will sound better in good headphones due to the proximity effect. They don't need to be powerful in the low range like speakers do.

If your headphones can produce the low end, and I'm only suggesting there are many that don't produce high volumes at low frequencies, many do, then your brain will fill in the missing bits and the proximity effect will take care of the lower volume.
[/quote]


I thought the proximity effect was something that happened with cardioid mics - how does this apply to headphones?

Anyway, the reason I brought the subject of headphones up was to challenge the myth that sound waves take some distance to 'form'. The distance between headphone driver and eardrum is about, what, - 50mm? That's the wavelength of a 6.8kHz tone, and whether or not headphones reproduce the bottom octave they certainly deliver a few octaves below 6.8kHz!

[TimR]

http://www.soundonsound.com/sos/1994_articles/mar94/headphones.html

I think the 'myth' is bought about because people are visualising sound waves as a snapshot of ripples on a pool. They seem to think that they're standing on a peak or in a trough depending in how far away from the speaker they are. This is only true if the sound wave is reflecting off a wall that is a certain factor of the particular wavelength in question away from the speaker. That's a very big oversimplification.

Really it's as most posters have said. Beaming, dispersion, room size and boundary effect. Not waves taking time to develop.

Edited June 23, 2013 by TimR