Abstract: A sound-limiting device is provided, that includes an earplug body of a resilient elastomeric material, and that has a first portion whose shape corresponds generally to the shape of the vertical canal of a dog's ear canal, and a second portion sized and configured to flex through the elbow region of the dog's ear canal and into the horizontal canal. A spring element can be encapsulated in the first portion of the earplug body, and configured to apply a spring bias radially outward from an axis extending a length of the earplug body. The spring element is of a shape memory alloy having a transition temperature that is below a normal body temperature of a dog. The device can also include a sound conditioning element configured to produce a signal that is audible to an animal wearing the device.