Thick-billed Grasswrens have some of the highest-pitched songs of any Australian birds I know - so much so that many people who suffer hearing loss can't hear them at all. Combine this with their relative rarity and reclusive habits and you have yourself one difficult bird to find. On a windy day forget it! They rarely break cover, and even if they sing, such high frequency calls are very hard to locate. When recording such high-pitched pulsed sounds, the levels have to be kept quite low to avoid distortion.