Sound waves vibrating at frequencies higher than humans can perceive are known as ultrasound. For the average person, sound becomes silent above 20 kilohertz (kHz). The ability of cats to hear these inaudible sound waves confirms that the feline auditory system is radically different from our own. A cat’s most acute sense is its hearing, which has been finely tuned over millennia to detect these high-pitched signals.
The Feline Hearing Spectrum
A cat possesses one of the broadest hearing ranges of any domestic mammal, spanning from low to extremely high frequencies. While human hearing stops around 20 kHz, a cat’s upper limit extends much further, sometimes reaching 85 kHz. This range is significantly greater than that of canines, whose hearing generally peaks around 65 kHz. The cat’s extensive range, running from approximately 48 Hertz up to 85 kHz, provides an advantage in detecting subtle environmental cues.
The Evolutionary Purpose of High-Frequency Detection
The cat’s ability to detect ultrasound is a direct result of its history as a specialized predator of small rodents. Rodents communicate using ultrasonic vocalizations (USVs), which are silent to the human ear. For example, distress calls in rats occur around 22 kHz, and mouse communication ranges from 30 kHz up to 120 kHz. The cat’s hearing range overlaps perfectly with these ultrasonic signals, allowing them to pinpoint concealed prey.
The external ear, or pinna, is controlled by approximately 30 individual muscles. These muscles enable the cat to rotate each ear independently by up to 180 degrees, functioning as directional sound funnels. This mobility aids sound localization, especially in the high-frequency range, helping the cat determine the direction and elevation of the source. By comparing slight differences in the time and intensity of the sound reaching each ear, the cat accurately maps the location of a faint squeak. This precise acoustic triangulation allows the cat to ambush prey, relying on sound even when visibility is low.
How Ultrasound Affects Cats in a Human Home
In a modern home environment, a cat’s sensitive hearing can become a source of irritation due to numerous hidden ultrasonic sources. Many common household electronic devices unintentionally emit high-frequency noise within the cat’s hearing range. These sources include poorly insulated computer power supplies, older television sets, fluorescent light ballasts, and sensors in some smart-home hubs.
The most deliberate source of ultrasonic noise is the electronic pest repeller, designed to emit frequencies in the 20 kHz to 65 kHz range to deter rodents. While effective against pests, these devices are highly aversive and stressful for the pet cat living in the same space. Prolonged exposure to continuous ultrasonic frequencies can be distracting, causing a cat to become anxious, agitated, or actively avoid certain rooms. Awareness of these silent sounds is important for maintaining a comfortable environment for a pet with a sensitive auditory system.