> import Sound.DF

> do { o <- lf_saw 500.0 1.0
>    ; audition [] (out1 (o * 0.1)) }

> do { f <- lf_saw 4.0 0.0
>    ; o <- lf_saw (f * 400.0 + 400.0) 0.0
>    ; audition [] (out1 (o * 0.1)) }