[pianotech] Do fourths beat faster?

[Ron Nossaman]

I've gotta wonder what planet I'm on this week when something 
like this comes up. In a decent aural tuning, where the 3rds, 
4ths, 5ths, 6ths, octaves, 10ths, 12ths, double octaves, 
17ths, and even triple octaves all fall into some reasonably 
sane relationship, the 4ths and 5ths beat at pretty much the 
same speed, respectively, throughout the scale. The 
determination of this is a result of listening rather than 
math and theory. Remember listening? Hands? This would be in 
the coin of the realm, or what nominally passes for ET. Do any 
of you actually produce tunings that have 4ths and 5ths 
audibly increasing in beat rate as you go up scale? If so, how?

Eternally mystified,
Ron N