#lang racket 
  
(require portaudio 
         ffi/vector) 
  
(define pitch 426) 
  
(define sample-rate 44100.0) 
(define tpisr (* 2 pi (/ 1.0 sample-rate))) 
(define (real->s16 x) 
  (inexact->exact (round (* 32767 x)))) 
  
(define vec (make-s16vector (* 88200 2))) 
(for ([t (in-range 88200)]) 
  (define sample (real->s16 (* 0.2 (sin (* tpisr t pitch))))) 
  (s16vector-set! vec (* 2 t) sample) 
  (s16vector-set! vec (add1 (* 2 t)) sample)) 
  
(s16vec-play vec 0 88200 sample-rate)