While playing games in DOSbox, I've noticed that, very randomly, the sound will play back at an extremely high pitch for about a split-second. It happens very quickly, but it's noticeable, especially when it happens several times in a couple of seconds. Sometimes it happens in clusters, sometimes it just happens once and it's done for a while.

I've grown used to it, but I'm still wondering what could be causing it.

Mixer settings:
nosound=false
rate=44100
blocksize=2048
prebuffer=5

SB settings:
sbtype=sb16
sbbase=220
irq=7
dma=1
hdma=5
mixer=true
oplmode=auto
oplrate=44100

My sound card is onboard audio on a Asus A8N32-SLI Deluxe motherboard.