[LAU] inverting phase of one channel - bad idea?

[Fons Adriaensen]

On Tue, May 27, 2008 at 12:23:57PM +0200, Atte André Jensen wrote:

> Fons Adriaensen wrote:
>
>> If the delay roughly corresponds to the path difference of one
>> ear to both speakers, and you do invert, then this is a primitive
>> form of crosstalk cancellation.
>
> So the delay part is crucial and the result can be good?
>
> I don't understand how long the delay should be (although I know how fast 
> sound travels and how far apart my ears are).
>
> Supposed I'm 10 meters away from a PA (speakers 10 meters apart), what 
> should the delay be? What if I'm listening at home, 3 meters away from my 
> home stereo (speakers 3 meters apart)?

It's not supposed to work in those conditions. What you need is
two speakers that you see in an angle of about 20 degrees (so
much closer than normal), and a distance of around 2 to 3 meters.
The 'sweet spot' is quite small. Two or more listeners should
be behind each other, not besides.

The required delay is very small, around 100 us.

> What if I'm listening through  headphones?

Bad idea ! Xtalk cancellation is used to *replace* headphones,
while allowing the listener to turn his/her head w.r.t. the
speakers. Allowing this makes the image much more 'real' than
with headphones.

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

Lascia la spina, cogli la rosa.