;*************************************   BINAURAL BEATS   ****************************************
; AN IMPORTANT ISSUE IN THE STUDY OF SOUND LOCALIZATION CONCERNS THE EAR'S ABILITY TO PROCESS
; PHASE DIFFERENCES IN THE EARS. ONE WAY TO STUDY THIS PHENOMENON IS TO PRESENT TWO SINUSOIDS OF
; SLIGHTLY DIFFERENT FREQUENCIES, ONE TO EACH EAR. AT LOW FREQUENCIES THE SOUND MAY APPEAR TO 
; FLUCTUATE OR BEAT SLOWLY AT A RATE EQUAL TO THE FREQUENCY DIFFERENCE BETWEEN THE TWO TONES.
; NOTE THAT THESE "BINAURAL BEATS" ARE QUITE UNLIKE THE PHYSICAL BEATS THAT CAN BE HEARD BY A SIN-
; GLE EAR. THERE, THE SMALL DIFFERENCE IN THE TWO FREQUENCIES CAUSES THE PHYSICAL STIMULUS TO WAX 
; AND WANE IN INTENSITY; IF THIS FLUCTUATION IS SLOW ENOUGH, IT IS EXPERIENCED AS A BEATING SENSA-
; TION. WITH BINAURAL BEATS, HOWEVER, THE INTERACTION BETWEEN THE TWO TONES OCCURS BECAUSE OF 
; SOME KIND OF INTERACTION IN THE NERVOUS SYSTEM OF THE INPUTS FROM EACH EAR.
; ONE MIGHT EXPECT THAT THESE BINAURAL BEATS WOULD OCCUR ONLY AT LOW FREQUENCIES, SINCE AT HIGHER
; FREQUENCIES IT IS DIFFICULT TO IMAGINE THAT THE NERVOUS SYSTEM CAN PRESERVE THE TEMPORAL STRUC-
; TURE OF THE WAVEFORM AT EACH EAR, A CONDITION THAT MUST BE MET FOR THEIR INTERACTION TO BE NOTICE-
; ABLE. THIS CONJECTURE IS SUPPORTED BY QUANTITATIVE MEASUREMENTS (LICKLIDER, WEBSTER, AND HEDLUN, 
; 1950). THEY FOUND THAT THE BEST BINAURAL BEATS  OCCURED AT FREQUENCY SEPARATIONS OF ABOUT 30HZ NEAR
; 400HZ AND MUCH SMALLER FREQUENCY SEPARATIONS AT THE HIGHER FREQUENCIES. NO BINAURAL BEATS ARE EVI-
; DENT ABOVE 1500HZ. TOBIAS (1965) FOUND THAT MEN APPEAR TO PERCEIVE BINAURAL BEATS AT HIGHER FRE-
; QUENCY THAN WOMAN, BUT THIS NEEDS MORE EXPLORATION.
; IN THIS DEMONSTRATION A 250HZ TONE IS PRESENTED TO THE RIGHT EAR, WHILE 251HZ TONE IS PRESENTED TO
; THE LEFT EAR.   
;*****************************************   HEADER   *************************************************


sr             =         44100
kr             =         4410
ksmps          =         10
nchnls         =         2 
 
 
 instr         1

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB 
 ifreq         =         p5                       ;P5 = FREQUENCY
                                                  ;P6 = PANNING FUNCTION FOR SIGNAL

 k1            linen     iamp,.05,p3,.05         
 a1            oscili    k1,ifreq,1             
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin