Don Pearce wrote:
On Sat, 02 May 2009 13:42:31 GMT, (Don Pearce) wrote:

On 02 May 2009 13:17:54 GMT, John Phillips
wrote:

On 2009-05-02, Jim Lesurf wrote:
In article , Rob
wrote:
Dave Plowman (News) wrote:
You bandy words like 'depth' etc without knowing what they mean.
Doesn't it (depth) just mean some sort of spatial representation of
sound? Like an instrument at the front, another a couple of feet behind,
a vocalist over there on the left, towards the back?
...and with a layout that was intended by those making the recording or
broadcast, and that - for relevant types of music - gives the same audible
layout as you would have experienced in the hall. Not just " blur out the
sense of location depth."
I have recently been thinking about the factors that lead to good depth
perception in stereo systems. I suspect there are depth cues which
can come from mono systems:

- amplitude (relative: quieter = further away)
- timbre (absolute: less HF = further away)

And stereo cues:

- image width (absolute: narrower = further away)

I am wondering if reflections matter, either "original" ones from the
recording venue or introduced ones from the listening room (which may
blur the originals).

Don mentioned 'speaker toe-in earlier. Since the frequency response of
'speakers off-axis tends to fall off at HF faster than at LF I suspect
toe-in matters somewhat in achieving good timbral depth perception.
The big depth cue in recordings, and which can be adjusted fairly
realistically even in close-miked multitrack, is the ratio of direct
to reverberant sound. Most reverb synthesizers (I use a convolution
reverb, which accepts impulses recorded in real spaces as the source),
and with that I can go from 100% direct to 100% reverb. You can
actually hear the player moving back and forth in front of you as you
change it.

d


Here's how it works. Quick speech recording, played against a constant
reverb impulse (a local church, in fact), repeated five times with the
ratio of direct and reverberant sound changed each time - final one is
reverberant only.

Obviously greatly exaggerated for illustration.

http://81.174.169.10/odds/depth.mp3

d

Which is a similar sensation I'd experience when valves are in the
amplification chain. I know (before you start!) that that doesn't
compute. It gives me a very believable notion of instruments (etc) and
spatial perspective.

Rob