It’s difficult to pinpoint the distance from which a dog can hear a human voice. For one thing, sound isn’t measured in distance, but rather in Hertz (frequency and pitch) and decibels (loudness). There are several variables involved that can affect the distance sound can travel, including loudness, pitch, tone and environmental factors that can either amplify or dampen the noise. Different breeds, as well as dogs of different ages, have different hearing abilities. As a general rule, dogs hear about four times better than humans.
A sound's pitch is determined by the frequency of wavelengths. This frequency is measured in Hertz, which is usually abbreviated as “Hz.” One wavelength cycle per second is 1Hz. Lower pitched sounds, like a foghorn or a bass guitar, have a lower number of Hertz, while the higher the pitch, the higher the number of Hertz. Generally, a human with normal hearing can hear sounds that are pitched between 20Hz and 20,000Hz. In contrast, dogs with normal hearing can hear pitches between 40Hz and 45,000Hz, with some breeds able to hear sounds as high as 75,000Hz. This is why dogs can hear sounds that are pitched too high for the human ear, such as a dog whistle, and why they sometimes start howling at sirens minutes before we can hear them.
How a Dog's Ears Work
A dog’s ear is made up of three parts. The outer ear includes the pinna -- the part that sticks out from the head and is covered in fur, which amplifies sound and funnels it into the ear canal. The middle ear includes the eardrum, three little bones called the hammer, anvil and stirrup, and the eustachian tube, which connects the middle ear to the back of the nose. The inner ear includes both the cochlea -- the hearing organ -- and the vestibular system that determines balance. More than 18 muscles control the movement and direction of the outer ear, allowing dogs to rotate and change the shape of their ears to better capture sounds.
Human Speech Frequency
The human voice typically falls between 300Hz and 3,000Hz, although some baritone voices can fall as low as 50Hz. Although this falls well within the range of a dog’s hearing, dogs typically hear best at a frequency of 8,000Hz. Because of this, dogs are more likely to hear higher-pitched voices, and may have an easier time hearing a female voice at a distance. This is why they are also more likely to respond to commands given in a higher-pitched tone of voice.
Age and Breed Differences
The size and shape of the pinna of a dog’s ear affects its ability to hear. Dogs with upright, erect ears, like a Chihuahua or German shepherd, generally hear better than dogs with large, floppy ears, such as a cocker spaniel. Breeds with a lot of hair around the ears, such as a poodle or Maltese, might have their hearing muffled if their ear hair isn’t properly groomed, and are sometimes prone to hearing loss from a buildup of hair and wax lodged in the ear canal. Age, of course, can affect hearing in dogs just as it can in humans. Puppies don’t begin to hear until they reach 3 weeks of age, and aging dogs are susceptible to hearing loss and deafness, with some breeds being more susceptible than others.