The cat's outer ear (pinna) is connected by 27 muscles and can rotate 180 degrees to scan the environment or to direct its attention to a particular source of sound. Cats can detect higher frequencies than dogs (e.g., a mouse's ultrasonic squeak). They can discriminate with 75% accuracy between two sound sources separated by an angle of only 5 degrees. The direction of the source of sound can also be calculated by the cat sensing differences in the time of arrival and intensity of sound received by the two ears. Rodents don't have more than a sliver of hope of escape when this little tiger is on the prowl!