BillFitzmaurice.info

Damm, so was I close??

Bill Fitzmaurice wrote:Close. It does so via the difference in the arrival times at the left and right ear, not volume, which would be imperceptibly slight.

My understanding is this holds true for frequecies between 120 hz - 3500hz. After that the frequencies have a short enough wavelength that your head acts like a boundry and shades (blocks) the higher frequencies from reaching the other side. At higher freqencies the volume of the sound in the ear facing the source would be much higher than the opposite ear shaded by the head and the brain starts to use that information for location. The exact frequency where this change starts to take place can be caculated by measuring the distance between the ears.

Interesting enough, around 3500hz the ears use both time arrival and relative volume for location. On the FM equal loudness curves, our ears are also most sensitive at that frequency.


In car audio to acheive perfect imaging you often see midranges in the kick panels to minimise the path length differences (arrival times) in the midrange. High frequencies (tweeters) are then imaged not by time arrival but by volume by placing the closest one off axis and the far one on axis to acheive relatively the same volume levels.

CoronaOperator wrote:
My understanding is this holds true for frequecies between 120 hz - 3500hz. After that the frequencies have a short enough wavelength that your head acts like a boundry and shades (blocks) the higher frequencies from reaching the other side.

Also, close. The different arrival times means that each ear hears the sound at a different point in the waveform phase; that's what it uses as a direction finder. Below approximately 120Hz the ears are too close together for there to be sufficient phase shift between their inputs, so the brain doesn't have adequate data to directionally locate. Larger animals, particularly elephants, don't have that problem. Above approximately 3500Hz the phase shift period is so short that the brain can't process the information fast enough. The shift period is long enough for smaller animals and birds with ears closer together to process. That's why we have trouble telling where a mosquito is but birds and bats don't.

CoronaOperator wrote:
Interesting enough, around 3500hz the ears use both time arrival and relative volume for location. On the FM equal loudness curves, our ears are also most sensitive at that frequency.

That's approxiamately the frequency that babies cry at. 'Tis a God thing.

Tom Smit wrote:

CoronaOperator wrote:
Interesting enough, around 3500hz the ears use both time arrival and relative volume for location. On the FM equal loudness curves, our ears are also most sensitive at that frequency.

That's approxiamately the frequency that babies cry at. 'Tis a God thing.

Evolution at its finest! Our success as a species depended on it a long long time ago. That particular frequency is more magical that you may think! Studies have shown that babies crying (3500 hz) also stimulates mothers milk production. Repeated exposure to that frequency also increases the breast size of adult females even if they are not the mother. In days of old if the mother died (quite common during child birth in ancient days) the baby would cry non stop and other female's breasts of the tribe would grow and take over the feeding.

On a side note; frequencies of 330 hz (harmonic of males voice) stimulate the sexual drive of females.

Disclaimer: I am not responsible what you pro audio guys with sine wave generators do with this information

Sooo .... I was planning on saving the best of the last piece of the puzzle about the magical 3500hz frequency for later. I just got off work a few hours ago and had a few wobbly pops so I am letting my guard down and am going to share the last piece of information I have now. Ready for it?

During my travels I came across a festival rider featuring national A talent performers that had many conditions for FOH engineers and one of the rules said something close to this :

(Preface, this was in a list of WRITTEN DOWN house rules posted in CLEAR VIEW of the sound engineers @ front of house.)

Rule # ???? (I don't remember) : "Guest cowboy engineers, please be a gentleman and remove your coyboy hat while in command"

I'm no country boy myself so I didn't understand the reasoning behind it. My first inclination was that this was an event that had certain customs that must be followed. When in Rome do what the Romans do right? After asking around I learned that the distance from the rim of the cowboy hat to the ears is about a quarter the wave length of 3500hz (see subwoofer placement sticky). That mean't that engineers working the mixing desk wearing a cowboy hat would hear a cancellation at 3500hz and not realizing it, boost those frequencies on the eq. That would be over compensating 3500hz making the mix unbalanced.

After that I thought that I understood that no cowboy hats at the desk made sense.

Now after some new information it all comes together.
The last piece of the puzzle is this:

#1 - the engineers @ FOH were only trying to do us boys a favor by boosting those 3500hz frequencies!

#2 - those cowboys and their magic hats that attenuate 3500hz (babies crying and significant female others telling us what to do) had the whole world figured out many years before the scolars did !

CoronaOperator wrote:
(Preface, this was in a list of WRITTEN DOWN house rules posted in CLEAR VIEW of the sound engineers @ front of house.)

Rule # ???? (I don't remember) : "Guest cowboy engineers, please be a gentleman and remove your coyboy hat while in command"

I'm no country boy myself so I didn't understand the reasoning behind it.

I don't understand the reason why country singers have to wear those stupid hats to begin with. Did their mamas never tell them that one does not wear a hat indoors? Do they think we'll mistake their songs for heavy metal or polka if they don't wear a hat? Have any of these clowns wearing cowboy hats ever ridden a horse? My guess is that the closest any of them have come to a horse was when opening a can of dog food.
FWIW I've been in the FOH for a few dozen country acts and, while many a doofus on stage felt that they had to wear a hat, I never saw one in the booth.

Bill Fitzmaurice wrote: I don't understand the reason why country singers have to wear those stupid hats to begin with. Did their mamas never tell them that one does not wear a hat indoors? Do they think we'll mistake their songs for heavy metal or polka if they don't wear a hat? Have any of these clowns wearing cowboy hats ever ridden a horse? My guess is that the closest any of them have come to a horse was when opening a can of dog food.
FWIW I've been in the FOH for a few dozen country acts and, while many a doofus on stage felt that they had to wear a hat, I never saw one in the booth.

ahhhhh.......Yankees......can't live with 'em.....can't shoot 'em.

Bill Fitzmaurice wrote:Above approximately 3500Hz the phase shift period is so short that the brain can't process the i

Does this mean it's only frequencies that are between the bass and 3500 Hz that are problematic or subject to phase shift & comb filtering?

Bruce Weldy wrote:

Bill Fitzmaurice wrote: I don't understand the reason why country singers have to wear those stupid hats to begin with. Did their mamas never tell them that one does not wear a hat indoors? Do they think we'll mistake their songs for heavy metal or polka if they don't wear a hat? Have any of these clowns wearing cowboy hats ever ridden a horse? My guess is that the closest any of them have come to a horse was when opening a can of dog food.
FWIW I've been in the FOH for a few dozen country acts and, while many a doofus on stage felt that they had to wear a hat, I never saw one in the booth.

ahhhhh.......Yankees......can't live with 'em.....can't shoot 'em.

Specially not that one.

I wore my cowboy hat on a country gig once, indoors. Everyone thought I was stylin' it. Ihave ridden a horse, does that get me a pass for the one night?

groig wrote: Does this mean it's only frequencies that are between the bass and 3500 Hz that are problematic or subject to phase shift & comb filtering?

No, because those are different phenomena that translate into frequency response that varies wildly with the listener position.

Bill Fitzmaurice wrote: My guess is that the closest any of them have come to a horse was when opening a can of dog food.

All hat and no cattle.

I wear a hat outside or whenever there is a draft, not because it looks cool but because it saves me from getting a mighty headache that may last up to a day. Should stay clear from boosting 3.5k (unless "carpenter's dreams" in vicinity), and start looking into local country acts that need an engineer or bass player

Anton,
Thank you so much for putting my posted idiom to good use

Bruce Weldy wrote:ahhhhh.......Yankees......can't live with 'em.....can't shoot 'em.

So if you're riding horses with yankees just wear a baseball cap and you should be fine.