Why do we feel Bass and how does it affect us?

gene

gene

Audioholics Master Chief
Administrator
Have you ever watched a bombastic movie in a theater with a heavy-duty bass system and felt as battered as the film's hero afterward? Ever wondered how a kick drum sound could cause that 'chest punch' sensation? Did you know that at a low enough frequency, high-amplitude sound may even be able to breath for you?

In this article we look at how bass is felt rather than heard, and, after reviewing some of the research that has been done in this area, we investigate the points at which low frequencies go beyond sound and become a tactile sensation in an experiment of our own with willing volunteers.

We caution readers NOT to try these experiments at home.



Read: Bass: the Physical Sensation of Sound

Please be sure to share your tactile bass stories with us here.
 
Last edited:
Klipschhead302

Klipschhead302

Senior Audioholic
Until I went to our local theater that upgraded to IMAX I haven't been too impressed with how theaters sound. Sitting in my living room with dual subs in the sweet spot you can feel the right parts pound you from the floor boards on up into your legs to your chest, during the depth charge scene my father in-law said his vision blurred (reference level or higher). That blew me away, other movies have had similar impact, gotta love it. :)
 
TLS Guy

TLS Guy

Seriously, I have no life.
Have you ever watched a bombastic movie in a theater with a heavy-duty bass system and felt as battered as the film's hero afterward? Ever wondered how a kick drum sound could cause that 'chest punch' sensation? Did you know that at a low enough frequency, high-amplitude sound may even be able to breath for you?

In this article we look at how bass is felt rather than heard, and, after reviewing some of the research that has been done in this area, we investigate the points at which low frequencies go beyond sound and become a tactile sensation in an experiment of our own with willing volunteers.

We caution readers NOT to try these experiments at home.



Read: Bass: the Physical Sensation of Sound

Please be sure to share your tactile bass stories with us here.
Gene I think you are a frustrated physiologist.

I'm glad you used only short bursts of low frequency sound.

Much of what you found out relates to high frequency jet ventilation technology.

Of all the vital organs to take a hit from severe insults the lungs are top of the list. Severe sepsis, trauma, burns and a myriad of insults trigger the adult respiratory distress syndrome, known as ARDS. In addition respiratory failure is the biggest challenge in the care of premature infants.

The upshot if this is that in ICUs the world over, mechanical positive pressure ventilation is required. Mechanical ventilation becomes required when there is an imbalance of lung compliance and respiratory effort. All shortness of breath has at its core a decrease in lung compliance unless the is neuromuscular failure, in which case there is still imbalance between force and compliance.

Now in normal respiration there is negative intrathoracic pressure in inspiration, and positive pressure on expiration. The negative phase is important in maintaining cardiac filling. Once mechanical ventilation is established, then on inspiration intrathoracic pressure is positive.

Under severe condition the lungs get stiff and boggy, and the pressure required gets to the point where the pressure is damaging and barotrauma starts to occur which can make recovery impossible. In addition positive end expiratory pressure is required to prevent the alveolar sacks where oxygen exchange takes place form collapsing.

In severe cases all this leads to a check mate situation. Peak airway pressures over 36 cm of H2O, plateau pressures over 30 cm of H2O and mean pressures over 16 cm H2O are associated with increasing lung damage or baratrauma as it is known.

In order to overcome this high frequency jet ventilation has found a place. In severe cases extracorporeal oxygenation can be tried, known as ECMO.

Now the high frequency jet ventilation in audio terms is low frequency in audio terms.

Frequencies employed vary from 1 Hz to 30 Hz and rates as high as 50 Hz have been tried.

The idea is to provide gas exchange without lung movement.

This also has application in ENT procedures where a tube though the vocal cords would make the procedure impossible. The canula can be placed in the supraglottic region, but the surgeon must keep the airway open. It is also used in delicate lung surgery where the lungs need to be still.

So where does all this link up with what you found?

Now the loudest sound that can be reproduced without distortion in free air is 194 db. That is because the rise and fall of pressure is one atmosphere. That is 1033 cm of water. That is a high pressure, but not enough to cause lung and other injuries. Serious injuries occur at 3 psi or around 15,000 cm H2O. Pressures over 9 psi or 45000 cm of H20 are almost uniformly fatal. So I don't think you will blow out a lung with a sub!

You started your test at 95 db and increased to 101db and then 112 db. So 95 db is 1.125 pascals or 0.0115 cm of of H2O. 101 db would be 2.24 Pascals or 0.02 cm of H2O. 107 db would be 4.48 Pascals or 0.0457 cm of H2O.

The lung, aorta, Carotid bodies of the carotid arteries, are full of baroceptors and so that likely explains why the deep base sounds are felt. There would be some ingress and egress of air in and out of the lungs.

In order for low frequency sounds to cause significant ventilation you would have to be at the 155 db spl point which would result in pressures of 1000 pascal or 10 cm of H2O.

I would expect that to have significant physiological effects on the subjects depending on frequency.

From studies of jet ventilation frequencies above 3 Hz are associated with increasing trapped gas volumes in the lungs. As a consequence and in addition airway pressures rise. Optimal frequency is open to debate but frequencies of around 1.7 Hz seem most popular.

So subjecting volunteers to spl of 150 db and higher at frequencies over 20 to 30 Hz range could be very hazardous and result in significant trapped air volume in the lungs, with consequent rise in intrathoracic pressure and reduction in cardiac output.

So Gene, I think you were wise to limit the spl where you did.

Changing gears the optimum speaker loading for these tests has been debated and transmission line loading favored for these studies. I note John Wright was referenced in my researches at TDL back in the sixties, when he constructed TL loudspeakers able to produce significant spl down to 7 Hz.

Personally I'm convinced that TLs do produce the best quality bass, and do it without fuss.
I noted a number of investigators have used TLs and actual organ pipes. The TL after all is a specialized Gadeckt organ pipe and couples to the space with the same attributes.

What I have noticed here is that it is not just movies that are impressive. These lines are in fact even more dramatic than the Twin Cites top Atmos theater in the bass. The thing that distinguishes these is how you get the chest and body vibrations at very low volume. Even in very soft passages you feel your chest and internal organs vibrate even when an organist just touches a low pedal softly and gently.

When I was at the Temple Church for my niece, wedding, in one piece Roger Sayer held a soft sustained deep pedal for a period of time. Everybody felt it and many where surprised. My wife looked at me and acknowledged these speakers sound exactly the same and produce just this effect.

A couple of nights ago I was playing a Gothic CD of the Wannamaker Grand Court Organ. It was around 11 PM and I had the volume well notched back. Much to my surprise, my nine your old grandson came up and said his bed was shaking! He was sleeping in the floor below, but not directly under this studio, which is over the garage.
 
DrJohnRead

DrJohnRead

Enthusiast
This research provides a wonderful insight into prior specialized findings on 'hearing' as a whole of body experience. Most who have been to live concerts know this to be the case. Audiophiles and listeners of good stereo and home cinema systems can begin to appreciate the much wider experience that 'listening' involves. Can we banish forever discussion of 'hearing' based purely on ear frequency curves now? Listening and hearing are far more potent biomechanical experiences that involve the whole body according to frequency and volume. This research including the informal tests conducted (well done team) show the patterns of sensation receptivity across the body and their variability.
I find this eye opening research that raises more questions than it answers. Can Berklee College of Music and similar music appreciation institutions please encourage research by students in these areas. We have so much more to learn here.
Best piece I have read on audio for a very long time. Thanks guys.
 
S

shadyJ

Speaker of the House
Staff member
Very erudite comment TLS Guy, thanks for posting that!
 
S

shadyJ

Speaker of the House
Staff member
This research provides a wonderful insight into prior specialized findings on 'hearing' as a whole of body experience. Most who have been to live concerts know this to be the case. Audiophiles and listeners of good stereo and home cinema systems can begin to appreciate the much wider experience that 'listening' involves. Can we banish forever discussion of 'hearing' based purely on ear frequency curves now? Listening and hearing are far more potent biomechanical experiences that involve the whole body according to frequency and volume. This research including the informal tests conducted (well done team) show the patterns of sensation receptivity across the body and their variability.
I find this eye opening research that raises more questions than it answers. Can Berklee College of Music and similar music appreciation institutions please encourage research by students in these areas. We have so much more to learn here.
Best piece I have read on audio for a very long time. Thanks guys.
Agreed, there should be serious research done on how sound waves effect the body and not just the ear from the perspective of music appreciation. Most of the existing research on the tactile experience of sound are done for industrial and military applications and also research for assisting the profoundly deaf. This would make a great project for someone's thesis.
 
Eng-399

Eng-399

Audioholic Intern
Great write up James I really enjoyed reading the article! It was a lot of fun doing this test with You and everyone that day!
The subs measure flat down to 13hz. in the room and there's 4 more subs Nearfield behind the last row of seats that we had off for the test. The last time we had the spl meter out it was pegged at 129.1 db. I think if everything was turned up the bass in there should be around 133 db. The future plan for the room is to add 4 more subs Nearfield which would bring it to 8 subs behind the last row and upgrading to better 18's up front with sanway clone amps to power them. My lcr keeps up with the bass in the room and with all the bass it makes it feel like your right there in the movie. The HT room is a lot of fun!!! things bass can do to you...
 
Last edited:
TLS Guy

TLS Guy

Seriously, I have no life.
Great write up James I really enjoyed reading the article! It was a lot of fun doing this test with You and everyone that day!
The subs measure flat down to 13hz. in the room and there's 4 more subs Nearfield behind the last row of seats that we had off for the test. The last time we had the spl meter out it was pegged at 129.1 db. I think if everything was turned up the bass in there should be around 133 db. The future plan for the room is to add 4 more subs Nearfield which would bring it to 8 subs behind the last row and upgrading to better 18's up front with sanway clone amps to power them. My lcr keeps up with the bass in the room and with all the bass it makes it feel like your right there in the movie. The HT room is a lot of fun!!! things bass can do to you...
I would not play at 133 db very long. That is 89 pascals or 0.9 cm of water.

140 db is 200 Pascals which is 2 cm of water. That will start having physiological effects and rise quickly at that point with frequencies above 3 Hz.
 
Klipschhead302

Klipschhead302

Senior Audioholic
I would not play at 133 db very long. That is 89 pascals or 0.9 cm of water.

140 db is 200 Pascals which is 2 cm of water. That will start having physiological effects and rise quickly at that point with frequencies above 3 Hz.
If I measure 128db at the listening position with a Radio Shack meter with the system cranked, how accurate would you say that might be? I have a lot to learn, so be gentle with your response. o_O
 
Irvrobinson

Irvrobinson

Audioholic Spartan
Great write up James I really enjoyed reading the article! It was a lot of fun doing this test with You and everyone that day!
The subs measure flat down to 13hz. in the room and there's 4 more subs Nearfield behind the last row of seats that we had off for the test. The last time we had the spl meter out it was pegged at 129.1 db. I think if everything was turned up the bass in there should be around 133 db. The future plan for the room is to add 4 more subs Nearfield which would bring it to 8 subs behind the last row and upgrading to better 18's up front with sanway clone amps to power them. My lcr keeps up with the bass in the room and with all the bass it makes it feel like your right there in the movie. The HT room is a lot of fun!!! things bass can do to you...
Frankly, I don't believe you. I've tested my system at 100db at 25Hz, and it was starting to make me nauseous after about 10 seconds. 129db would probably be absolutely disorienting. Were you in the room when you ran this test?
 
TLS Guy

TLS Guy

Seriously, I have no life.
If I measure 128db at the listening position with a Radio Shack meter with the system cranked, how accurate would you say that might be? I have a lot to learn, so be gentle with your response. o_O
The Radio Shack meters never claimed to be calibrated. Tests of these units have found 12 db discrepancies, between units.

I very much doubt you achieved 128 db. If you got to 100 db I would be surprised. What equipment were you testing?
 
Klipschhead302

Klipschhead302

Senior Audioholic
Frankly, I don't believe you. I've tested my system at 100db at 25Hz, and it was starting to make me nauseous after about 10 seconds. 129db would probably be absolutely disorienting. Were you in the room when you ran this test?
Frankly, I don't care if people believe me, I make no claims of absolute accuracy, which is why I asked. I was sitting in the listening position. I can't find the 128db video, here is the 124db video. As I stated, UNSCIENTIFIC.

At the levels measured, the experience was extremely intense.

 
Last edited:
Klipschhead302

Klipschhead302

Senior Audioholic
The Radio Shack meters never claimed to be calibrated. Tests of these units have found 12 db discrepancies, between units.

I very much doubt you achieved 128 db. If you got to 100 db I would be surprised. What equipment were you testing?
Well, even if off 12db, that's still 112db, I'm not here to brag, but if they're off that much why are they so highly recommended?

The system is a Marantz SR5003, Klipsch RF-82's and dual MFW's in two corners of the room.

Here is a 6 year old picture, the speakers and subs haven't changed from when I took this. The rest of the gear, like the Blu-Ray, TV and DVR have been replaced.



Here is an even older picture, but it shows the placement of the subwoofers properly.

 
S

shadyJ

Speaker of the House
Staff member
Frankly, I don't believe you. I've tested my system at 100db at 25Hz, and it was starting to make me nauseous after about 10 seconds. 129db would probably be absolutely disorienting. Were you in the room when you ran this test?
Irv, the highest 25 Hz test signal hit 110 dB but it only lasted for 5 seconds, and also came in pulses, not a continuous tone. Eng-99's system does hit 129 dB, but that is with complex movie content and all channels blazing away. The subs alone wouldn't be able to do that at a single deep bass tone, but they can hit pretty hard. This was measured with a calibrated Galaxy CM-140 SPL meter.
 
N

nickboros

Audioholic
Very interesting article. I found the experiment that was performed on the 9 individuals in a somewhat scientific manner to be the most interesting part. The deep bass region has a pressure sensation on the head and ears. The midbass had more of an effect on the chest, especially between 50 and 60 Hz. We can boost that region slightly to get that "chest punch" that most of us like.

Then we get to something that I was not really aware of before, the upper bass region from 100 to 200 Hz is where we feel the bass throughout the entire body. One solution that was proposed was making sure the main speakers were larger speakers that are up to the task of pressurizing the space in these frequency range. Wouldn't a better solution be to just cross the subwoofer over higher? Of course one would want 2 or 4 subwoofers to make sure the bass is uniform and we don't have one subwoofer now being localizable, but it seems like the subwoofer would be much more up to the task in this range than the main speakers. Or getting a pair of midbass modules (Hsu or Rythmik have these) to handle 80 Hz to 200 Hz and then hand it over to the main speakers at 200 Hz. Is there any downsides to this approach?
 
Irvrobinson

Irvrobinson

Audioholic Spartan
Irv, the highest 25 Hz test signal hit 110 dB but it only lasted for 5 seconds, and also came in pulses, not a continuous tone. Eng-99's system does hit 129 dB, but that is with complex movie content and all channels blazing away. The subs alone wouldn't be able to do that at a single deep bass tone, but they can hit pretty hard. This was measured with a calibrated Galaxy CM-140 SPL meter.
Thanks, now that sounds a lot more realistic.
 
Eng-399

Eng-399

Audioholic Intern
When we took that measurement it was with everything going in the room I should of been more specific about that. So I don't know exactly what frequency we got the reading of 129db. There's 8 subs in there total not just the 4 that are posted in the picture. When playing the movie live die repeat (EOT) the first 20 second clip is a 10-20 HZ bass note and when playing it feels like wall above is going to come down on you and my door in the room slaps the door molding so hard I'm worried about causing damage to the room. I wish I would of metered that and see how loud the subs play during that part. We had underworld awakening playing during the fight clip at the end of the movie.
All of the sub amps have limiters set on them to at 1150 watts so nothing is clipping. I'm working on upgrading the subs at this time and also adding 4 more subs Nearfield on top of the 4 that are already in place.
The whole test was a lot of fun and I'm glad I was able to see how bass effects the human body. Thanks James for doing the test in my room.
 

Attachments

Last edited:
TLS Guy

TLS Guy

Seriously, I have no life.
Very interesting article. I found the experiment that was performed on the 9 individuals in a somewhat scientific manner to be the most interesting part. The deep bass region has a pressure sensation on the head and ears. The midbass had more of an effect on the chest, especially between 50 and 60 Hz. We can boost that region slightly to get that "chest punch" that most of us like.

Then we get to something that I was not really aware of before, the upper bass region from 100 to 200 Hz is where we feel the bass throughout the entire body. One solution that was proposed was making sure the main speakers were larger speakers that are up to the task of pressurizing the space in these frequency range. Wouldn't a better solution be to just cross the subwoofer over higher? Of course one would want 2 or 4 subwoofers to make sure the bass is uniform and we don't have one subwoofer now being localizable, but it seems like the subwoofer would be much more up to the task in this range than the main speakers. Or getting a pair of midbass modules (Hsu or Rythmik have these) to handle 80 Hz to 200 Hz and then hand it over to the main speakers at 200 Hz. Is there any downsides to this approach?
Once you get out of the 60 to 80 Hz range then the system needs to be totally integrated in design with custom crossover. Even in the lower range a custom crossover is best.

If you start using mid bass modules etc you will have all sorts of horrid band pass gain issues and a mess, that will not sound good at all.

For all these reasons I integrated my design. And yes, you do need more power from 80 Hz to 400 Hz then from 20 to 80 Hz to properly reproduce music.

An awful lot written here about subs, the need for them and how to use them is pure bunk. In fact there is no other topic on this forum that contains more misinformation.

Much more attention needs to be given to the other speakers, especially the front three rather then the sub.

If you spend time here you will think that the sub is considered the most important speaker. Good speakers do not miss a sub, period.

I think a lot of this comes about because most speakers are awful and 1000 fold or more harder to design and build than a sub.

Most people are just turning up the sub and covering a multitude if ills. It never fools me.

There seem to be lots of good subs. Good main speakers rare, and good centers almost non existent. That is the problem, not lack of subs.
 
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top