The mechanics of hearing | Music And Perception (Music + Audiophile Forum)

The mechanics of hearing Sept 10, 2019 10:19:53 GMT 10 Audiophile Neuroscience likes this

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Post by sandyk (RIP Alex, 1939 - 2021) on Sept 10, 2019 10:19:53 GMT 10

Sept 9, 2019 18:21:11 GMT 10 Audiophile Neuroscience said:

In real life you get one set of inter-aural differences for left and right ear for the various cues (in level, time, frequency) per sound source. With stereo sound reproduction there are two sets of inter-aural differences for left and right ear, as created by left and right speaker. So its not the natural way we perceive real sound objects.

There is the experience of some that eliminating this 'cross talk' between stereo channels ie preventing left channel stereo info from reaching the right ear and vice versa will result in better localisation and overall a more natural and life like sound. The reasoning would appear to be that it is closer to simulating how a real sound source is perceived ie returning to one set of inter-aural differences for the various cues.

STC is the expert on such matters. If understanding the effect is like headphones but playing outside, not inside of the head.

Nonetheless, By manipulating the mix of sounds in stereo reproduction (and whatever else sound engineers do like EQ) a very convincing illusion of multiple sound images on a soundstage can be created. Using the stereo phantom central image as example, perception of location relates to amplitude and delay panning (with phase also affected but differently for each frequency). Psychoacoustically the brain perceives that the image is located away from the time delayed speaker and towards the not time delayed speaker and similarly for loudness differential. As I understand it, this is then further influenced by room and speaker interactions. Omnidirectional speakers in rooms with lots of early reflections will produce a larger image that will float between the speakers and tend to stay fixed irrespective of whether you get up and move around the room according to Art Noxon (acoustics engineer and Master Physics).

This is exactly what I heard with mbl radialstrahler speakers in an untreated room (sandyk (RIP Alex, 1939 - 2021) may have heard these at Dennis' place?). In most acoustically treated rooms which dampen first reflections and with more directional speakers (like mine), when you get up and move to the left or right the image and stage shift smoothly to the left or right. In problem rooms, the image collapses to the loudspeaker that is closest to you.

Usually for me the central image is at about the level of the plane of the speakers.The vocal in some recordings push out a bit forward of the speakers. This might be in recordings that have some midrange "presence" boost in the Eq? I think Barry Diament bdiament explained that sometimes due to direct and reflected sound combining in an untreated recording booth, a dip in midrange can occur and the engineer unnecessarily compensates by boosting the mids. When played back it sounds brighter and edgier than it should. He didn't mention pushing the image forwards.

David

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"All music is folk music. I ain't never heard no horse sing a song." -
- Louis Armstrong

Hi David

I remember these problems well , with all the finger clicking by Dave trying to get the best positioning in that room.

I presume that is the occasion you were speaking of ?

Regards

Alex

The mechanics of hearing Sept 10, 2019 12:36:44 GMT 10

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Post by Audiophile Neuroscience on Sept 10, 2019 12:36:44 GMT 10

Sept 9, 2019 19:25:25 GMT 10 STC said:

You are actually getting three sets of cues. If you take an example of a trumpet at 15 degrees to the left, both speakers would need to produce the sound so that the image emerges at that location. If you turn off the right speaker, the image would be coming from the left speaker (330 degrees) and if you turn off the left speaker the image will be at 30 degrees.

As you can see in the absence of one speaker, you are localizing the point of sound where it originally emerges without difficulties because all the cues confirms to spatial hearing. However in stereo, your brain is fighting between two localization and chooses the third phantom image. For a person who experience stereo for the first time would find this to be very unnatural. The multiple images also corrupts the solidness of the phantom image and buries other information which will be too low to be standing out on its own.

Here is an example, how s stereo system will never be able to retrieve the correct information from the recording using the conventional stereo playback method. In this video if you were to use headphones, you would clearly hear the male and female were separated to the right and left. Use headphones and you would clearly hear the separation. However, no matter how costly or high end is your system, it would never be able to produce the separation as good as headphones due to crosstalk.

This my early attempt to do crosstalk for normal stereo speakers set at 60 or so degrees. The effect is about 30 percent or so compared to true Ambiophonics method but you would generally get an idea. If you wish to experiment this with your high end system, forward me you fovourite track and I would process them for you to do A/B yourself with your high end system. The video contain Famous Blue Raincoat for comparison.

p.s. I am limited to very few samples due to copyright and finding the correct examples.

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Okay thanks ST, fascinating. I am going to come back to this next week when I get some time to devote to doing some relaxed listening tests
David
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"All music is folk music. I ain't never heard no horse sing a song." -
- Louis Armstrong