Exercising and Enhancing the Senses - Hearing

Dogs’ ears come in many shapes and sizes — long and short, floppy and erect, and all variations in between. Dogs’ ears are surprisingly mobile. More than eighteen muscles control the pinna, or earflap, alone, which allows the nuanced movements that make dogs’ ears so expressive and so good at picking up sounds. Dogs move their ears to communicate how they are feeling. They also move their ears to facilitate hearing. Every dog owner will recognize the “pricked ears” of a dog who is suddenly attentive. The up and open ears allow dogs to best capture sound. The ear muscles also allow dogs to turn their ears like a periscope to follow the direction of a sound. If we watch a dog’s ears for cues, we can likely gather information about our surroundings that we would have missed. Marc used to watch his dogs’ ears when hiking around their mountain home, which they of course shared with all sorts of wild animals. When there were cougars, black bears, or other potential predators around, the dogs’ ears perked up and their noses often tilted upward. Marc took these responses as signals that it was time for all to head home immediately to avoid a possible confrontation.

Dogs have far more sensitive hearing than humans and can detect much quieter sounds. Their sense of hearing is about four times as sensitive as ours, so what we hear at twenty feet, a dog can hear at about eighty feet.1 They also hear a lot of things we don’t because they can hear higher-frequency sounds. From available data, scientists suggest that dogs hear in frequencies as high as 67,000 cycles per second (also called hertz), while humans hear frequencies up to 64,000 cycles per second.2 This means there are some sounds that are inaudible to us but quite available to our dogs. For example, they can hear the high-pitched chirping of mice running around inside the walls or in the woodpile. Also, some of the electronics in our homes emit constant high-frequency sounds we don’t notice but which can be distressing to dogs.

Relatively little systematic research has been done on how dogs use sound and hearing in their interactions with the world and in their encounters with people and other dogs. We know that dogs make a lot of different sounds, including growls, barks, whines, whimpers, howls, and pants, but scientists don’t fully understand how these different vocalizations function in interactions with others. And we also don’t know which aspects of vocal communication have evolved specifically to facilitate social interactions with humans. For instance, dogs are the only canid species to bark frequently, but perhaps surprisingly, we still don’t know all that much about what dogs are trying to say with their barks. Preliminary data also suggest that dogs seem to “laugh.” During play, dogs will emit a kind of forced exhalation called the “play pant,” which seems to be used to initiate play and to signal during play “this is still play, and not a fight.”3 It will be fascinating to see how research into canine vocal communication evolves.

Many people use verbal commands or vocal signals to communicate with their dog. As we mention in the section on sight, dogs may pay more attention to gestures than they do to spoken commands, and they may get confused when our visual and auditory signals don’t align. Researchers have also found that dogs listen not only for certain words but to tone of voice, and intonation may be more important in how dogs read a signal than the actual word spoken. Using fMRI techniques, researchers at a dog cognition lab in Hungary scanned the brains of dogs as the dogs listened to recordings of their trainers’ voices. The trainers used praise words (such as “well done”) and neutral words (such as “however”) and spoke them in a high-pitched “good dog” voice and in a neutral voice. The results of this study showed that dogs used their left hemisphere to process the words, and their right hemisphere to process the intonation, or emotional content, of the words, which is how human brains process speech. When praise words were spoken with a praising intonation, the reward center of the brain was activated, but not when praise words were spoken with neutral intonation. In other words, dogs listen to the words and the emotional content of our speech, and the emotional content has more salience.4

Unlike other senses — particularly smell and taste — where pet dogs often suffer from a lack of sensory stimulation, hearing can entail the opposite problem. Dogs often suffer from too much noise or from exposure to sounds that they find aversive or frightening, which constitute serious freedom inhibitors. Of course, we should try to give our dogs the freedom to hear and communicate with sounds, but we also need to think about the overall soundscape and protect dogs from noises they don’t like.

BARKS AND GROWLS: THE LANGUAGE OF DOGS

Barks and growls are two of the most common dog vocalizations, and they are used to communicate with both other dogs and humans. Vocal communication in dogs is extremely complex and not very well understood. In her analysis of dog vocalizations, German ethologist Dorit Feddersen-Petersen notes that even the meaning and function of barking is controversial. Some scientists consider barking a highly sophisticated acoustic form of expression, while others think barking is “noncommunicative.”5 Dog barking is difficult to study for a whole variety of reasons, including the fact that dogs come in a huge variety of shapes and sizes. There are big differences in the length of the vocal tract and thus in the sound quality of vocalizations. Just think of the difference between the bark of a Great Dane and of a Yorkie. Are they even speaking the same language?

Feddersen-Petersen believes that barks have definite communicative significance, and dogs use them to convey information about motivation and intention. Dog barks have a mixture of what scientists call “regular” (or harmonic) and “irregular” (or noisy) acoustic components. While wolves vocalize using noisy components only, dogs use a whole range of harmonic and noisy forms in various mixtures. Different breeds of dogs seem to have evolved unique vocal repertoires, ones based on the human environments in which they have lived. Assessing the meaning of a bark — or more accurately, a string of barks, since barks are rarely singular — is challenging and requires looking at the context and whether the bark elicits a response from a social partner (either a dog or human). It may be that barking and other vocalizations have evolved particularly to facilitate dog-human social interactions.

One way to get to know your dog better is to make an ethogram focused solely on the various barks, growls, and other sounds they use in your company and in the company of other dogs. Can you distinguish between different kinds of barks — such as sharp and high-pitched; low-pitched; coming in a steady stream or in short bursts, and so on — and can you identify what may have triggered the bark? For example, was it the postal delivery person walking by, another dog barking in the distance, or impatience because you are slow getting your shoes on for the morning walk? After studying the vocal sounds of your own dog, watch other dogs in your neighborhood or at a dog park.

Barking is a key part of the natural behavioral repertoire of dogs and is likely an important means of communication. Letting our dogs be dogs means letting them talk with one another, which means letting them vocalize. Of course, barking is often treated as a problem, and “excessive” barking — which is always defined by humans — can become a very serious issue for dog owners. A barking dog can be incredibly annoying to us and perhaps to other dogs and animals. Excessive barking is a common reason for dogs being relinquished to shelters, and it can be one of the more frustrating aspects of dog ownership. While some barking is normal, too much barking can be a sign of boredom, frustration, or stress. Trainers and dog psychologists can often help identify underlying issues that might drive excessive barking. If dog barking really bothers you, it’s probably best not to get a dog.

Sometimes people deal with a dog who barks too much by having the dog’s voice box surgically removed. In one particularly shocking case of “problem barking,” a couple in Oregon was ordered by a court to have the voice boxes of their six dogs removed because they had failed to control the dogs’ barking over ten years.6 “Debarking” — or “bark softening,” as some euphemistically (and offensively) call it — involves severing the vocal cords and is, simply put, seriously harmful to dogs. The procedure permanently eliminates one of the dog’s main means of communication, which qualifies as a severe freedom inhibitor. Severing the vocal cords is never the best response to barking behavior, and a dog who has been subjected to this horrific procedure can no longer really function comfortably as a dog.

In addition to barking, dogs often growl. Whereas barks are often used to communicate at a distance, growls are generally low volume and used in close communication. Different kinds of growls carry distinct meanings and have different emotional content. For example, during play, including during tug-of-war between dogs or between a dog and a human, a dog may growl quite loudly, without showing any teeth, but this is usually meant as part of play and not to signal genuine anger or aggression. Growls produced as serious warnings will likely be low-pitched and come either from the chest or mouth, with varying levels of bared teeth. Research has shown that dogs growl “honestly” in serious encounters (the “size” of the growl accurately reflecting the size and aggression-level of the dog), but they show more variability in their growling when they play. Even when dogs growl during play, it almost never leads to fighting (less than 2 percent of the time).7 Dogs can reliably distinguish between a prerecorded “food growl” and a “stranger growl” and respond appropriately.8

Whatever else growling may mean, it clearly can be used as a serious warning or signal of potential aggression, so we need to pay very close attention to the rest of a dog’s body language when a dog growls. Humans are not always very skilled at reading the intention of dog growls, though people with more experience around dogs are better at distinguishing between playful and aggressive growls, and women appear to do better than men.9 As with all the senses, it’s important to become dog literate and learn as much as you can about your dog’s growls. Along with a “bark ethogram,” consider also making a “growl ethogram” for your dog.

WHINING AND WHIMPERING: A CALL FOR HELP

Two other common types of vocalization are whimpering and whining. These are distinct vocal communication patterns, although they are sometimes hard to distinguish and many people lump them together as “crying.” Whining tends to be louder and higher-pitched, while whimpering is quieter and lower. Whimpering usually means that a dog isn’t feeling well and is sick, nervous, or in pain. The communicative function of whining is not as clear.

A 2017 study on the relationship between dog vocalizations and separation-related anxiety is a good example of the kind of research we need to better understand and help our dogs. Excessive barking is typically considered one of the main symptoms of separation-related disorder (SRD) in family dogs, but in this study, Peter Pongracz and his colleagues wanted to confirm whether dogs with separation anxiety vocalize their distress through barking, through whining, or by using both vocalizations. Pongracz’s team found, contrary to popular belief, that dogs with separation anxiety were more likely to whine than to bark, particularly at the departure of their human, and that “early onset and abundance of whining may serve as a reliable tool for diagnosing SRD.” Whines and barks likely reflect different inner states. Another interesting finding from Pongracz’s study was that a dog’s age was the most influential factor in determining onset and abundance of barks during a short separation. Younger dogs barked sooner and more than older dogs.10

One common myth about “crying” in dogs is that dogs always whimper when they are in pain. While it is true that dogs in pain will sometimes whimper, they don’t always vocalize their distress. A lack of whimpering does not mean a dog isn’t in pain, since sometimes dogs only whimper when pain has progressed to an intolerable level. At that point, just as in humans, the cause of the pain has often progressed to a point where it is more difficult to treat. With any injury or medical problem, the ideal is to notice pain early and address the cause quickly with appropriate care or medications. There are two lessons here: 1) If your dog is whimpering, it’s possible that something is seriously wrong, so please seek the advice of a veterinarian; and 2) don’t rely on vocalizations alone to determine whether your dog is uncomfortable. Be sensitive to other behavioral cues, such as body posture and mobility, and investigate any suspected problems right away.

BABY TALK AND YOUR DOG

Nearly everyone has either done it or seen it done with a dog. Someone kneels down, vigorously rubs a dog’s face and head, and starts cooing and babbling: “What a sweet boy! Aren’t you a sweet boy? Look at those sweet little paws! Who loves their baby, huh?” Dogs often feel like furry, excitable children, and so we use “baby talk” with them, or as scientists call it, “infant-directed speech . . . characterized by higher and more variable pitch, slower tempo and clearer articulation of vowels than in speech addressed to adults.”11

Is this a problem? Do dogs like it or care, or do they simply tolerate it because they have no choice? And why exactly do we engage in this bizarre behavior?

A study published in 2017 tried to shed some light on pet-directed speech. The researchers learned that although people are more likely to use baby talk with young puppies, they also consistently use this speech pattern with older dogs. For their part, young puppies were more drawn to baby talk than normal human speech, while older dogs seemed to ignore it.12

Thus, with dogs, it seems like we sometimes prefer to treat them like children, no matter how old and mature they are. Does baby talk harm dogs? Probably not in itself. Since it nearly always expresses our affection, many dogs probably enjoy it to one degree or another. Then again, older and other dogs may find it grating and confusing, much like human adults would if spoken to that way. Observe your own dog to see what their reaction is, if anything, to this type of speech.

However, animal ethicists aren’t so keen on baby talk because they say it may reinforce a tendency to “infantilize” dogs and ignore their intelligence and agency as individual beings with specific, dog-related needs, such as the need to run free with other dogs. Similar to when people dress up dogs in pink tutus or tartan sweaters, baby talk may encourage people to treat dogs like toys or dolls, as unaware objects to play with, rather than as subjective, sentient individuals.

TURN DOWN THE VOLUME: PROTECT YOUR DOG’S HEARING

With the senses of smell and taste, we’ve discussed how sensory deprivation can be a serious freedom inhibitor. The opposite is more often true with hearing. Our world can at times be very loud and noisy, and certain sounds can be very distressing to our canine companions, so an important freedom enhancer is to respect a dog’s need for quiet and to avoid auditory overload. We might like to turn AC/DC or Spinal Tap up to eleven, but it is likely that screeching, feedback-filled rock music is actually painful to a dog’s ear. If you like to play loud music — or if you do anything that creates very loud, high-pitched noise, like running a vacuum cleaner or using power tools — always make sure your dog has a place to go that is protected from the sound.

Above all, pay attention to a dog’s behavior for signs that an environment is too painfully noisy for them, for whatever reason. For instance, Jessica once attended a summer Gin Blossoms concert at an outdoor venue in Fort Collins, Colorado. In theory, it was an ideal venue to bring a dog, and people were spread out on blankets and folding chairs in the grass. However, perhaps because the concert was outdoors, the sound was turned up so loud that the music was actually distorted, and Jessica had to cover her ears with her hands and leave early because the sound was physically painful. She wasn’t alone. About fifteen feet away from her was a couple with their dog, who was clearly agitated, with his ears pulled back, tail down, and panting. His owners seemed totally oblivious to the dog’s discomfort and showed no intentions of leaving.

Just as with people, it’s also likely that dogs can suffer permanent damage and hearing loss from long-term exposure to extremely loud noises. There has been no research into noise-related canine hearing loss, but plenty of research confirms the effects on human hearing, and there’s no reason to think that a dog’s ears are any less sensitive to damage. It’s well known that hunting dogs can experience noise-induced hearing loss. Even the sound of a single gunshot or explosion, if it occurs too close to a dog, can rupture the eardrum or damage the inner ear. Further, ear infections can also cause permanent hearing loss if not treated properly.

We owe it to our dogs to pay close attention to all the sounds we expose them to and to do what we can to protect their long-term health. However, perhaps the easiest hearing-related freedom enhancer you can provide for your dog is to silence their dog tag. If dogs could talk, that might be their number-one noise complaint. The constant jingling of the tag on their collar gets in the way of listening to the world around them, particularly when they are walking, running, or playing, and this keeps them from fully using their acute sense of hearing to experience their surroundings. Tag silencers — little neoprene covers that hold the tags together — are a cheap intervention that will be greatly appreciated by your dog.

BE SENSITIVE TO NOISE PHOBIAS

Many dog guardians know that certain sounds send their canine companion into a tizzy fit. Some of the common culprits are fireworks, gun sounds, and thunder. Indeed, studies suggest that nearly half, and perhaps as many as three-fourths, of all family dogs are afraid of certain noises and will show at least one behavioral sign of fear when exposed to them.13 These behavioral signs include trembling, shaking, panting, salivating, hiding, and peeing or pooping in the house. These fear responses are often called noise phobias, particularly when the fear is related to a specific stimulus (such as a thunderstorm) and when the behavioral response is extreme, such as scratching through a wooden door trying to escape.

People may chuckle when they pop Bubble Wrap and their dog trembles in fright, but noise phobias are no laughing matter. The trembling is a sign of acute stress, and stress, as we know, is bad for your health. When people get genuinely scared, they sometimes joke that it “just took a year off my life!” Well, there is some truth to this, and we should take these fears seriously. Our dogs deserve it.

To help reduce the chance that noise phobias will develop, we can avoid exposing puppies to frightening sounds, and we can socialize puppies to a wide variety of sounds. There’s some evidence that early exposure to a frightening sound increases the risk of developing a related phobia, so as much as possible, protect puppies from sudden or loud noises. Then, some people also find that gradual desensitization to a scary sound can help prevent phobias and, in some cases, help a dog move past their fears. As part of their puppy socialization classes, the Humane Society of Boulder Valley (Colorado) includes a gradual exposure to the sound of fireworks. A very soft recording of fireworks popping is played in the background while the puppies are given a constant stream of treats and praise. Each week the volume is increased just a bit. The puppies don’t even notice the fireworks because they are so interested in getting treats and playing with the other puppies.

Despite these efforts, dogs may still develop aversions to certain sounds, and we must do our best to protect our friends from them. In addition, noise sensitivity can be an indicator of pain, so when dogs show fear or anxiety with loud noises, a visit to the veterinarian may be in order.14 In extreme cases, dogs with noise phobias may need to see a behavioral specialist. Prescription medications may help relieve anxiety in some dogs, and they could be used prophylactically in situations where people cannot control the source of a noise, such as thunderstorms and July Fourth fireworks.15

DOGS NEED YOU, NOT THE RADIO

Sometimes when a dog must be left alone for long periods of time, people turn on the TV or radio, hoping that this will comfort or “entertain” the dog the way it might a person. However, this may not actually be doing a dog any favors. It’s unlikely that television images — even of jumping squirrels — music, or an audiobook will be inherently interesting to them. If anything, the noise of a TV or radio might interfere with a dog’s ability to hear outside sounds, which might be more important. Most dogs consider it a vital part of their job to protect their family and their home, so they may prefer to spend their day listening to “natural” sounds from outside, which are likely more interesting, stimulating, and enriching.

Leaving a radio on all day won’t hurt a dog (unless the volume is too loud), and indeed, some dog trainers and veterinarians report that certain kinds of music and recorded sounds can have a calming effect and may have some application in treating separation anxiety and noise phobias.16 But all in all, TV, radio, and music aren’t substitutes for human interaction. The best treatment for separation anxiety, loneliness, and boredom is to not leave a dog alone for long periods of time.

by Marc Bekoff and Jessica Pierce.

Note

1. Beth McCormick, “Fido Can Hear You, but Is He Really Listening?” Starkey Hearing Technologies, November 1, 2017, https://www.starkey.com/blog/2017/11/can-my-dog-understand-me.

2. George M. Strain, “How Well Do Dogs and Other Animals Hear?” Deafness in Dogs & Cats (Louisiana State University), last updated April 10, 2017, https://www.lsu.edu/deafness/hearingrange.html.

3. P. R. Simonet, M. Murphy, and A. Lance, “Laughing Dog: Vocalizations of Domestic Dogs during Play Encounters,” paper presented at the meeting of the Animal Behavior Society, Corvallis, OR, 2001.

4. A. Andics et al., “Neural Mechanisms for Lexical Processing in Dogs,” Science 353 (September 2016): 1030–32, http://science.sciencemag.org/content/353/6303/1030.

5. Dorit Feddersen-Petersen, “Communication — Vocal: Communication in Dogs and Wolves,” in Encyclopedia of Animal Behavior, ed. Marc Bekoff (Westport, CT: Greenwood Press, 2004), 385–94.

6. Aimee Green, “Owners Must Surgically ‘Debark’ Loud Dogs, Court Rules,” Oregonian, August 31, 2017, http://www.oregonlive.com/pacific-northwest-news/index.ssf/2017/08/owners_must_surgically_debark.html.

7. Bekoff, “A Dog Companion’s Guide,” chap. 9 in Canine Confidential.

8. Tamás Faragó, “Dog (Canis familiaris) Growls as Communicative Signals” (PhD thesis, Eötvös Loránd University, Budapest, 2011), http://teo.elte.hu/minosites/ertekezes2011/farago_t.pdf.

9. Tamás Farago et al., “Dog Growls Express Various Contextual and Affective Content for Human Listeners,” Royal Society Open Science 4 (May 17, 2017): 170134, doi: 10.1098/rsos.170134.

10. Peter Pongracz et al., “Should I Whine or Should I Bark?: Qualitative and Quantitative Differences between the Vocalizations of Dogs with and without Separation-Related Symptoms,” Applied Animal Behaviour Science 196 (November 2017): 61–68, doi: 10.1016/j.applanim.2017.07.002.

11. Tobey Ben-Aderet et al., “Dog-Directed Speech: Why Do We Use It and Do Dogs Pay Attention to It?” Proceedings of the Royal Society B 284 (January 11, 2017), http://rspb.royalsocietypublishing.org/content/284/1846/20162429.

12. Ibid.

13. Emily Blackwell, John Bradshaw, and Rachel Casey, “Fear Responses to Noises in Domestic Dogs: Prevalence, Risk Factors, and Cooccurrence with Other Fear Related Behaviour,” Applied Animal Behaviour Science 145 (2013): 15–25, https://www.appliedanimalbehaviour.com/article/s0168-1591(12)00367-x/abstract. See also Katriina Tiira, Sini Sulkama, and Hannes Lohi, “Prevalence, Comorbidity, and Behavioral Variation in Canine Anxiety,” Journal of Veterinary Behavior 16 (2016): 36–44, https://pdfs.semanticscholar.org/a3de/432e01cbfbc60c17a662219d6262344b2451.pdf.

14. “Dogs with Noise Sensitivity Should Be Routinely Assessed for Pain by Vets,” Phys-Org, March 20, 2018, https://phys.org/news/2018-03-dogs-noise-sensitivity-routinely-pain.html.

15. M. Korpivaara et al., “Dexmedetomidine Oromucosal Gel for Noise-Associated Acute Anxiety and Fear in Dogs: A Randomised, Double-Blind, Placebo-Controlled Clinical Study,” Veterinary Record 180, no. 14 (April 8, 2017), https://www.ncbi.nlm.nih.gov/pubmed/28213531.

16. “Research,” iCalmPet, accessed September 8, 2018, https://icalmpet.com/about/music/research.