psychoacoustics, how do we determine distance?

[PV Audio 5,000+ posts]

Yeah, but that's still different than hearing someone clap a 1/4 mile away with your eyes closed (let's assume the sound perceived by your ear is 50dB). If you somehow had a stereo that you could cart in without being heard and perfectly reproduces sound and play that same clap but at a lower intensity (keeping it 50 dB), you'd be able to tell that the clap is right next to you. If the same amount of stimulus is given to the eardrum, how is it that we know where it's coming from and how far away it is?

And **** you thadman for making me curious as **** about this //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[PV Audio 5,000+ posts]

Shit like this fascinates me. For example, consider that sound is only air being moved via vibration from a surface. You snap your fingers and the flesh of your palm reflects the vibration through the air and to your ear. But what about your average cellphone? I read a study where a celluar phone's speaker can be heard from up to 1/3 a mile away in normal conditions (don't ask for a source for that because it was in a magazine that I bought in March, popular science I think). How is it that that tiny speaker is able to move air in all directions for you to be able to hear it distinctly over other sounds which might have similar frequency?

 

[newusername 10+ year member]

I posted about this on DIYMA. I recommend buying Brian Moore's book: An Introduction to the Psychology of Hearing. I can't recall the chapter this is discussed in, but can post it later. The book is relatively affordable (under $100) and is considered one of the marquee psychoacoustic books available.

 

[joetama 5,000+ posts]

I'm going to have to go to the library after I pay my late fees... //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

When you think about sound being a slight vibration in the air molecules and being able to hear a cell phone ringer 1/3 away from a phone. That is just amazing...

So, I assume that we have ruled out sound pressure as a factor in knowing distance. Sound Pressure does help sound go farther, but louder doesn't sound closer... Or does it?

Could it be directivity? Because, the farther away from a sound source you are the wider the pattern is...

 

[newusername 10+ year member]

Sound pressure plays a part if you can interpret how much sound pressure is supposed to exist at the source. This is why interpreting distance works much better for human speech than for typical sounds. Echo effects make things easier, but our ears really do **** at distance localization.

 

[thadman 10+ year member]

Shit like this fascinates me. For example, consider that sound is only air being moved via vibration from a surface. You snap your fingers and the flesh of your palm reflects the vibration through the air and to your ear. But what about your average cellphone? I read a study where a celluar phone's speaker can be heard from up to 1/3 a mile away in normal conditions (don't ask for a source for that because it was in a magazine that I bought in March, popular science I think).

1/3 of a mile? Wow. I'm interested also. Assuming 6dB loss for every doubling of distance, the direct signal should be down about 50dB before reaching the ear and the intensity of the reflections really depends on your environment (if it was winter, the snow will absorb most of the wavelengths whereas if it was summer in the city they'd reflect off the buildings). How low was the noise floor? How loud was the original signal? What did they consider "able to be heard"? above the noise floor? measurable? slightly above the threshold of hearing?

Do you still have the article? You willing to scan it?

How is it that that tiny speaker is able to move air in all directions for you to be able to hear it distinctly over other sounds which might have similar frequency?

The cell phone should be omnidirectional as a result of its size. I'm not sure exactly how large the radiating surface of the cell phone speaker is, but its probably somewhere in the

 

[PV Audio 5,000+ posts]

Sound pressure plays a part if you can interpret how much sound pressure is supposed to exist at the source. This is why interpreting distance works much better for human speech than for typical sounds. Echo effects make things easier, but our ears really do **** at distance localization.

That is EXACTLY what keeps ****ing me up though. Someone screaming at you from a mile away might only be as loud as a whisper, but you know that the sound is extremely loud (assume you can't see the person) and extremely far away because your mind knows that something that sounds like that is only produced at high intensity levels. You can't yell quietly, so how would you know that they're far away even if you played that same sound at the same level right next to you?

 

[PV Audio 5,000+ posts]

1/3 of a mile? Wow. I'm interested also. Assuming 6dB loss for every doubling of distance, the direct signal should be down about 50dB before reaching the ear and the intensity of the reflections really depends on your environment (if it was winter, the snow will absorb most of the wavelengths whereas if it was summer in the city they'd reflect off the buildings). How low was the noise floor? How loud was the original signal? What did they consider "able to be heard"? above the noise floor? measurable? slightly above the threshold of hearing?
Do you still have the article? You willing to scan it?

The cell phone should be omnidirectional as a result of its size. I'm not sure exactly how large the radiating surface of the cell phone speaker is, but its probably somewhere in the The article itself really had nothing to do with audio, it was about some new infrared cellphone that only allows people wearing a wireless headset to hear the "ring". Something like that, and they used that figure to talk about how obnoxious the sound is.

 

[joetama 5,000+ posts]

Something else to think about...

If someone yells at you from 1/2 a mile away you are only going to hear the peaks in the audio signature.

While if they whisper in your ear at the same volume you would no only hear every part of the audio signature but you would hear them breathing, and if they were near enough to you could even hear their heart beat...

 

[PV Audio 5,000+ posts]

Something else to think about...
If someone yells at you from 1/2 a mile away you are only going to hear the peaks in the audio signature.

While if they whisper in your ear at the same volume you would no only hear every part of the audio signature but you would hear them breathing, and if they were near enough to you could even hear their heart beat...

Okay, bad example //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif
Same situation, but with a single tone. Even if you hear it faintly, you'd be able to tell if it was far away.

 

[joetama 5,000+ posts]

Well you still would only be able to hear a lesser signal...

 

[T3mpest 10+ year member]

I'd bet most of the ability to judge distance is due to common experience. Neither inter-aural time differences or interaural intesity differences would provide good distance localization cues. You need a bit of both to get a rough guess though. A sound that is attenuted to 60db's from a distance of 500 feet won't have the same frequency content as one that is quieter at a closer distance. The high frequency content would be filtered out. Having seen how far away on object that has that level of filtering would allow the brain to quickly compare, giving you an intuitive guess, at least outdoors. Echoes would make this a bit easier as well. The echo's strength wouldn't be as depenent on the distance from the source. As far as I know this is the only real answer. It's why the human's are so bad at determining distance, we don't have any built in adapations to do so, it's simply rough estimates due to previous experience. Using tones in a controlled environment, I doubt we could do it at all //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif No echoes, and no previous knowledge of how loud it should be.

All in all humans are probably worse at judging depth than they are azimuth cues or height.

 

[joetama 5,000+ posts]

I think that humans are better at depth than you credit...

We can't exactly determine 'that sound is 4ft 3 in away' but we can pretty accurately determine 'that sound is coming from the other side of the tracks' or 'that animal is on the other side of the mountain'

 

[T3mpest 10+ year member]

I think that humans are better at depth than you credit...
We can't exactly determine 'that sound is 4ft 3 in away' but we can pretty accurately determine 'that sound is coming from the other side of the tracks' or 'that animal is on the other side of the mountain'

again, mountains have echoes and sounds in a environment with train tracks are likely to have been heard before as a reference. Tones in a controlled evironment, doubt it.

 

[goodstuff 10+ year member]

//content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif He's asking probably the only brilliant question I've ever seen on this forum, and you have to come in and post some useless bullshit to make yourself feel more important? It's a theoretical question, and unless you have full knowledge of the Sabin levels of different materials and how that relates to distance from your ear, why wouldn't you see if someone else knows? I sure as hell would like to know the answer.

x2. Just shut up.

On a more intelligent note you may find this thread interesting:

http://www.diymobileaudio.com/forum/showthread.php?t=5664

Not a member there myself...but the op werewolf seems to be on the same level as you in terms of discussion.