The Most Important Spec Sheet: The Human Ear - Page 2

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Quote:

Originally Posted by bigshot 

I think it would be useful to assemble a spec sheet for human hearing, outlining the thresholds of human perception. That way people can put published specs in context. Feel free to suggest specs and link to citations, and I'll assemble them to this top post. I'll start it out...

DYNAMIC RANGE

Peak volume 130 dB (threshold of pain)
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/earsens.html
 

I think it's rather misleading to think of the dynamic range of human hearing in the same way we do a piece of electronic gear.

Yes, we can hear down to the thermal noise floor of the air itself, and up to the threshold of pain at 130dB. But NOT AT THE SAME TIME.

Just being exposed to relatively low levels of ambient noise reduces our threshold of hearing. If put into an anechoic chamber, it takes time for your ears to acclimate before you can get down to the lowest threshold. Now consider what it's like when listening to music at modest levels.

Bill Waslo had an interesting challenge a while back. He had a number of files, some of which contained just the music of a particular snippet of music. Some had some Sousa band playing at I believe 70dB down. The challenge was to use ABX to determine which files had the Sousa band included. I don't believe anyone has scored statistically significant on that challenge.

But what it demonstrates is that the effective dynamic range of human hearing is considerably less than 130dB.

se

I guess Sousa bands / marches are just that unmemorable and unnoticeable.  

Quote:

Originally Posted by Steve Eddy 

 

I think it's rather misleading to think of the dynamic range of human hearing in the same way we do a piece of electronic gear.

 

Yes, we can hear down to the thermal noise floor of the air itself, and up to the threshold of pain at 130dB. But NOT AT THE SAME TIME.

 

Just being exposed to relatively low levels of ambient noise reduces our threshold of hearing. If put into an anechoic chamber, it takes time for your ears to acclimate before you can get down to the lowest threshold. Now consider what it's like when listening to music at modest levels.

Yes, the ear can alter it's accoustic profile and can be thought of as having a sort of gain adjustment. http://hyperphysics.phy-astr.gsu.edu/hbase/sound/protect.html#c1  The DR is cited 120db for old people... their anvils and stirrups and what not stiffen up and can't reduce the amplitude of waves, so they reach the pain threshhold sooner. So, yes, technically you can't hear 30db/130db simultaneously. But I'm at a loss to think of a number that could be used in replace of pain threshold. 

BTW, is there any way to bargain on that 30db noise floor? Can we find out the max recommended level for a recording studio and go with that number? Granted nobody lives in an anechoic chamber, but 25db seems easily attainable, and 30db is more than 2x as loud as that.  

But sounds, even noise, can be heard under a "noise floor", so there can be some argument about usable range under the noise floor.  A further issue is that the noise floor of a listening room isn't a white / pink / whatever idealization.  Some noise sources aren't constant.  There are almost always some tonal spikes that bring up the overall reported dB figure.  That means that a trough in the response, outside of those peaks, may be at a fairly low level.

In terms of usable dynamic range, masking effect of the music itself is often more relevant.

Quote:

Originally Posted by mikeaj 

 

 

Does anybody have the references on distortion audibility?  These seem to be a bit over the map as well.  Furthermore, under what circumstances are these tested?  Some levels quoted are far below what transducers can manage.  e.g. If you're using a test signal with 0.05% THD (5th harmonic only) @ 1 kHz test tone vs. 0.01% through transducers with 0.1% THD, what does that really mean?

They are, the audibility varies greatly with program material. The lowest with pure tones is around 1%.

Interesting find for jitter reference, 1974 BBC study placed the figure at 35ns above 2khz for 95% of the population. It appears that subsequent surveys are within an order of magnitude of that figure.

As for the spec sheet itself, "The Human Ear" is a little misleading for a title, the final limiting factor is neurological. Also, should one consider the extremes of the curve, the outliers who can hear above 20khz and have perfect pitch?

Quote:

Originally Posted by bigshot 


Subtract the noise floor of a quiet room from the treshold of pain and you come up with a pretty fair maximum possible dynamic range... 100dB.

Well then, it should be pretty trivial for you to tell which of Bill's files have the Sousa band playing at just -70dB.

http://www.libinst.com/diffmaker_example_files.htm

Scroll down to "...and a listener challenge."

se

Quote:

Originally Posted by mikeaj 

I guess Sousa bands / marches are just that unmemorable and unnoticeable.  

Yeah, they don't exactly spin my beanie either.

se

Quote:

Originally Posted by mikeaj 

But sounds, even noise, can be heard under a "noise floor", so there can be some argument about usable range under the noise floor.

Yeah. But in the context I'm speaking of, the music you're listening to is the "noise." The question being, how far down below the music can you hear?

se

Quote:

Originally Posted by Steve Eddy 

 

Well then, it should be pretty trivial for you to tell which of Bill's files have the Sousa band playing at just -70dB.

 

http://www.libinst.com/diffmaker_example_files.htm

 

Scroll down to "...and a listener challenge."

 

se

I'm not very confident, but this is my crack at it: 

Quote:

Originally Posted by bigshot 


Remember, we're talking about specs for regular people playing their stereo. A whisper quiet library setting is about the best one could hope for in a normal living room with central air.

Audiophiles are faced with a million theoretical exceptions. That's what makes spec sheets so indeciferable to them. It just leads to overkill. I'd like to keep these specs reasonable and straightforward so someone can hold them up against the specs for an amp or DAC and actually be able to put them into context of what they actually might be able to hear.

ok, ok, I understand the goals. I'll desist.

Quote:

Originally Posted by bigshot 


Remember, we're talking about specs for regular people playing their stereo. A whisper quiet library setting is about the best one could hope for in a normal living room with central air.

Audiophiles are faced with a million theoretical exceptions. That's what makes spec sheets so indeciferable to them. It just leads to overkill. I'd like to keep these specs reasonable and straightforward so someone can hold them up against the specs for an amp or DAC and actually be able to put them into context of what they actually might be able to hear.

I think that the noise floor with a pair of IEMs and a pair of closed headphone's with average isolation should be noted as well, since several people do listen with those here.

Almost forgot, a couple of links for HD: http://www.audioholics.com/education/acoustics-principles/human-hearing-distortion-audibility-part-3, http://www.alpsadriaacoustics.org/archives/Full%20Papers/Furdek_Harmonic%20Distortion%20Perception%20Threshold.pdf