Antecedent: Eric is grinding our kitchen knives against the knife sharpener.
Behaviour: I cover my ears with my hands and sing to myself while chattering my teeth.
Consequence: The metal grinding noise is blocked (negative reinforcement).I shutter even writing about this one. I hate the sound of metal rubbing on metal. It's horrific. It hurts. I can't even stand watching it because the anticipation of the sound I know it makes causes me to tense up. To ease that feeling, I have learned a repertoire of behaviours to block that noise out - covering my ears, leaving the space entirely, singing or humming to myself (although it's often a shrill "eeeeeeeeeeeeek" that gets the job done), sucking on my cheek or chattering my teeth together to create additional noise. I cannot sort cutlery without doing a combination of these things. I work with individuals who have very real sound aversions. They might have aversions to the announcements over the PA system, the school bell ringing, the sound of large trucks going by, appliances when turned on etc. Even the pitch of someone's voice can be aversive. It may be common for them to cover their ears, but I am also finding many of the individuals create additional noises as perhaps another way to block the noise. If it is successful, they are going to do it again the next time that awful noise is present. It may seem insolent or that they are being disruptive on purpose, but I hope you now take time to consider what else is going on in the environment. Pay attention to the sounds going on around you. Any one of them could be the antecedent to their behaviour.