heres how one way to make sound on N64 :

Crazy nation trainer  (xtremeG version)



   

     [we tested button and its time to make sound!]

       lui     $t4,8031       ;make pointer to 'yes' sound

       addiu   $t4,$t4,4F10   ;80314f10 = start

       addiu   $t5,$zero,4A71 ;4A71=length

       addiu   $t6,$zero,1388 ;1388= DAC rate

       addiu   $t7,$zero,0001 ;1=BIT rate

       jal     here

       nop

    [draw yes]

......



   [we tested button and time to make 'no' sound]

         lui     $t4,8031        ;make pointer to 'no' sound

         addiu   $t4,$t4,12C4    ;803112C4

         addiu   $t5,$zero,3C45  ;3C45=length

         addiu   $t6,$zero,1388  ;DAC rate

         addiu   $t7,$zero,0001  ;1=BIT rate

         jal     here

         nop

    [draw no]



.....        

         [...initialize vid, audio]

           addiu   $t4,$zero,0000  ;[blank out sound]

           addiu   $t5,$zero,0000  ;initialize

           addiu   $t6,$zero,0001

           addiu   $t7,$zero,0001

here:      lui     $t8,A450

           sw      $t4,0000($t8)  ;start RDRAM address

           sw      $t5,0004($t8)  ;length

           addiu   $t9,$zero,0001 

           sw      $t9,0008($t8)  ;1 = enable dma

           sw      $t6,0010($t8)  ;dac rate 

           sw      $t7,0014($t8)  ;bit rate 

           jr      $ra

           nop