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[Frank Koenig]

When my buddy and I go to the cabin the in Sierra foothills we've taken to watching movies and TV series in the evening on my laptop. (Thank covid and POSSIBLY the improved quality of such entertainment). There are two old sofas, symmetrically disposed around a coffee table, one of which is distinctly less comfortable than the other. There also is an installed sound system, that the laptop feeds via Bluetooth, with speakers high on one wall.

The trouble is that the sucky sofa faces the speakers so last time we decided to sit in the good sofa and let the sound come from behind. (The laptop sits on a carboard box on the coffee table.) At first it was a little weird, as expected. But we both strongly observed that after about 10 minutes the dialog, sure as shit, sounded like it was coming from the little people on the screen. This reminds me of the famous experiment where the subjects wore image-inverting glasses and after a day or two everything appeared right-side-up. Now and then, in the movie we were watching, there would be a bit of hard-panned foley, like someone slamming a door on one side of the room. This instantly blew the illusion with the sound coming from behind and one side. After they went back to talking the dialog would, in a sentence or two, revert to coming from the screen. Crazy thing the brain.

--Frank

[Steve-White]

It's exactly like the inverted vision experiment.  Hearing, like eyesight is matrix'd in the brain as is vision.  It's learned, mapped, processed and the "program" can be adjusted.

We each have our subjective perception of the physical world.  You and I agree that red is red, yet what you see and what I see as red isn't the same.

When I first started live mixing it was almost overwhelming.  Then with time and practice I could isolate each component, hum from the guitar, ringing drum head, etc.  Now listening is different than before, it can't be "undone' - I listen to the music, but can also pick out each instrument or voice.

[Scott Helmke]

I've got a weird psychoacoustic thing, not sure if it's just me that gets it.

At the end of a piece of music, when it's fading out or the last notes are fading out, it often sounds like the whole thing goes sharp. 

Weird, eh?

[Keith Broughton]

I've got a weird psychoacoustic thing, not sure if it's just me that gets it.

At the end of a piece of music, when it's fading out or the last notes are fading out, it often sounds like the whole thing goes sharp. 

Weird, eh?

I have had similar experiences.
Sometimes, after mixing a loud band, when I play the break music, it sometimes sounds off pitch.
As for the OP comment, I would imagine if you turned your head, the "front sound source" illusion would be broken.
It's amazing what the brain does to give us a sense of "reality". Maybe it's all an illusion! Maybe we are in the Matrix 

[John Roberts {JR}]

That is the heavy lifting that our brains do, trying to make sense of sensory input.

JR

[Tim McCulloch]

I've got a weird psychoacoustic thing, not sure if it's just me that gets it.

At the end of a piece of music, when it's fading out or the last notes are fading out, it often sounds like the whole thing goes sharp. 

Weird, eh?

Most all 'natural' pitch sources that require a physical, vibrating object will go sharp as they decay.  You can hear it with a piano very easily, same with a single string pluck on a guitar or viol.

You can easily see it on a device like the old Conn Strobe-Tuner.

[Ivan Beaver]

It is part of the reason a lot of Churches use IMAG (Image magnification) but putting the Pastor on large screens.

When you can see a persons mouth move (assuming not to much out of sync), it is easier to understand what they are saying, even if you are not a lip reader.

And for the same reason, it is harder to understand when the lips and sound are out of sync by a fair bit, unless you close your eyes.  It is confusing information.

[Frank Koenig]

As for the OP comment, I would imagine if you turned your head, the "front sound source" illusion would be broken.

Yes. I found this to be true. It then takes a few seconds of watching the moving mouths for it to drift back in. -F

[Frank Koenig]

Most all 'natural' pitch sources that require a physical, vibrating object will go sharp as they decay.  You can hear it with a piano very easily, same with a single string pluck on a guitar or viol.

Might this be because we disproportionately perceive the higher modes, which are inharmonically sharp, as the sound decays?

[John Roberts {JR}]

Most all 'natural' pitch sources that require a physical, vibrating object will go sharp as they decay. 

Plucked string instruments, and struck drumheads in my experience are generally somewhat higher pitch (sharp?) when first struck due to transiently higher string/drumhead tension. This higher pitch is short lived and note frequency stabilizes pretty quickly as mechanical components relax. Longer term decay tails AFAIK have relatively stable pitch.

You can hear it with a piano very easily, same with a single string pluck on a guitar or viol.

You can easily see it on a device like the old Conn Strobe-Tuner.

This phenomenon was explored at length by guitar synth developers decades ago.

There is a phenomenon with some wind instruments when overtones can be triggered by higher pressure playing.

===

Instruments that make complex sounds (like drums) can sound different as volume decays and Fletcher-Munsen preferentially hears mid range components.

JR

[Scott Helmke]

Might this be because we disproportionately perceive the higher modes, which are inharmonically sharp, as the sound decays?

That's my best guess so far. If the fundamental drops out I definitely tend to notice the effect.  Happens on recordings most of the time.

[Lee Douglas]

Reminds me of listening to a familiar song on the radio out really low volume (barely audible) and then turning it up and realizing your brain has been "hearing" it in the wrong key the whole time!

[Art Welter]

There also is an installed sound system, that the laptop feeds via Bluetooth, with speakers high on one wall.

 Now and then, in the movie we were watching, there would be a bit of hard-panned foley, like someone slamming a door on one side of the room. This instantly blew the illusion with the sound coming from behind and one side. After they went back to talking the dialog would, in a sentence or two, revert to coming from the screen. Crazy thing the brain.

--Frank

Frank,

Our perception of sound location being directly "in front" or "behind" results from the reduction of high frequency sound entering the ear canals blocked in the "shadow" of the ear's pinna, while the shape of the pinna's convolutions creates vertical frequency related differences.

From what I've read, wireless Bluetooth has at least 32ms delay, so your brain must re-map the "too late" dual source audio to the moving lip "source" regardless of the actual sound coming from behind. The impulse response of the hard-panned single-source door slam gets the old "hunter (or hunted) brain" going again, as it stops believing the illusion and locates the source via L/R intra-aural time difference as well as the frequency response differences between the first arrival and room echos.

The hearing aids I'm using (Phonak-P90) have a latency of only around 6ms, quite low considering all the detection algorithm, EQ and dynamic processing with two A/D conversions. Now while riding my bike I can hear birds tweeting, but can't pinpoint their location unless I stop- the 6ms delay between the unamplified sound below 3kHz and amplified HF directly inserted in the ear canal messes up the brain's location mapping.

Fortunately, I'm not reliant on small bird hunting for my sustenance 

Art

[Keith Broughton]

There is a phenomenon with some wind instruments when overtones can be triggered by higher pressure playing.

So THAT's why the sax is always sharp
It really is interesting how the brain works with sound (and other sensory inputs) and if I had a life do over, I would go into the study of psychoacoustics.

[Mike Monte]

So THAT's why the sax is always sharp

When a sax player tunes it is done with a "straight tone" (no vibrato) firm embouchure.
When a sax player performs with vibrato it is usually done as a "jaw vibrato" where the player loosens and re-tightens his "embouchure" (jaw, mouth, lip grip on the mouthpiece) with each pulse.
The relaxing of the embouchure makes the pitch go flat at the bottom most part of the vibrato thus the overall pitch with vibrato will sound flat.  To compensate for this sax players usually tune a bit sharp so that when he/she uses vibrato the pitch is in the pocket (intonation-wise).
or
maybe it could be that the sax player you referenced is a hack  

[John Roberts {JR}]

So THAT's why the sax is always sharp
It really is interesting how the brain works with sound (and other sensory inputs) and if I had a life do over, I would go into the study of psychoacoustics.

The classic example is flute when played pianissimo (low volume) it makes a nearly pure sine wave, blow louder and generate more overtones.

JR

[Steve-White]

So THAT's why the sax is always sharp
It really is interesting how the brain works with sound (and other sensory inputs) and if I had a life do over, I would go into the study of psychoacoustics.

Which would have been a very fascinating career.

Allow me to add a twist to consider.  I've worked with German Shepherds in K9/Protection work since 1973.  At first it was about "training" and of course the capability of the dog itself.  Police, military or executive level personal protection work isn't something that's "trained into" that dog, it's developing the capabilities that the dog already possesses in large part and associating with commands.

Every dog is different, each develops in a unique fashion.  They are not trained automatons that follow commands.  There is a relationship and bond between handler and dog.  For instance doing a narcotics search or tracking we watch the dog's body language and know if it's "on" or "off" of the scent or trail.  As well when the dog alerts in a bite mode.  Always trust your dog.

What's the correlation to this topic?  Back to the trained dogs each being unique and not being an automaton that follows specific commands with fully predictable behaviors - yes when commanded to sit they sit.  But, when commanded "Find him" or "Find it" or "Seek" or "Get him" it's a whole different ball game - then the dog is somewhat on autopilot.

Over the years I've realized it's not just a "Trained Dog" you get - what you really get is access to the dogs faculties - hearing, scent, sight and aggression - they are an extension of the handler and the relationship is symbiotic.  It's amazing.  The team part, for example would be during a search for contraband in a building or area where the handler directs the dog where to look.  Or, when searching for a bad guy hiding or lost person to guide the dog into the wind for airborne scent.

Having access to a nose that's ~5000 times more acute than mine is quite an experience.

[John Roberts {JR}]

Over the years I've realized it's not just a "Trained Dog" you get - what you really get is access to the dogs faculties - hearing, scent, sight and aggression - they are an extension of the handler and the relationship is symbiotic.  It's amazing.  The team part, for example would be during a search for contraband in a building or area where the handler directs the dog where to look.  Or, when searching for a bad guy hiding or lost person to guide the dog into the wind for airborne scent.

Having access to a nose that's ~5000 times more acute than mine is quite an experience.

Dogs are now being used to detect covid with high 90 percentile accuracy.

JR

[Dave Garoutte]

Isn't "Weeep Weep Weeep" the Psycho acoustic effect?

[Steve-White]

Isn't "Weeep Weep Weeep" the Psycho acoustic effect?

Possibly more "Psycho" than acoustic...

[ProSoundWeb Community]