The effects of sound and music on our patients and workplace (Proceedings)

Sound is an important part of an animal's surroundings, and should be considered when taking a history on an anxious or reactive pet. Many owners don't realize the significance of sound in their homes, and most veterinarians are not cognizant of the sonic environment their hospitalized patients are exposed to.

Sound consists of waves of energy. How fast a wave is traveling, or its frequency, is measured in hertz (Hz). One Hz is defined as one wave cycle per second. Humans hear frequencies of 20 – 20, 000 Hz, and dogs hear between 40 – 65,000 Hz.

Loudness is measured in decibels (dB):

Hearing damage occurs at 100dB, but can also be caused by prolonged exposure to levels above 85dB.

Psychoacoustics is the discipline that studies the perception of sound in humans. This includes how we listen, our psychological responses, and the physiological impact of music and sound on the human nervous system. Bioacoustics is the study of sound in animals. It looks at how animals communicate, as well as the positive and negative effects of sound in their environments.

Much of the discipline of psychoacoustics is based on the principles of resonance and entrainment. Resonance describes the effect of one vibration (or frequency) on another, i.e., the vibration of sound causing a change in the frequency of a vibration of a cell, muscle, organ, etc. Entrainment is the process by which periodic rhythms cause major body pulse systems (heart rate, brain waves, and breath) to naturally speed up or slow down.

Pattern identification is another component of psychoacoustics, and is related to the complexity of sound. When a new pattern is introduced, the focus of the brain turns to this sensory input. This is termed active listening. Once the pattern has been processed, the brain returns to a passive hearing state. This is an instinctive process which also occurs in animals, called the orienting response

The orienting response is a survival mechanism, and is especially important in prey animals. The ear pinna on dogs, cats and horses allow the reception of sound to occur on a much more sensitive level than in humans. We have all witnessed the sudden arousal of an animal when an unusual or loud sound is heard. While the orienting response can have a positive effect on the animal's survival, there are also negative consequences to it. As animals have been domesticated, and housed in unnatural environments, they have been exposed to sounds that may continually activate their orienting responses. Even though the environmental sounds may not elicit overt fear, the ongoing instinctive reaction to sudden noise can interrupt the animal's relaxed state.

Different animals show different sensitivities to all types of environmental input. Several species of laboratory animals have been studied for sensitivities to sound. One study in dogs showed transient increased in blood sugar following 5 – 10 minutes of sound exposure at 80 dB. There was individual variation among dogs, with reactive dogs exhibiting the most significant change.

Noise pollution is a growing problem in human society, and has been linked to a decrease in immune system function. While no specific research in this area has been done in dogs or cats, studies in mice, rats and humans suggest that immune compromise may be a possibility. As the field of immune research advances in both humans and animals, clarification on the role of noise pollution can be obtained. When we consider that the average American household watches seven hours of television daily, and with the increasing use of electronic gadgets and gaming devices, noise pollution could be a real influence on our veterinary patients' health and well-being. With clients asking questions about behavior in 45% - 90% of visits to the family veterinarian, we should consider what affect noise pollution has on these statistics.

If you have a patient that is reactive or anxious, consider gathering an "environmental history". You may want to ask about television habits, construction in the area, and whether or not the family lives on an ambulance run. Clients can also participate by taking their own sonic inventories. Have them spend a few minutes at different times of the day paying attention to the sounds in their home. They should also note their animal's reaction to those sounds. Noises that clients have become accustomed to may be a source of anxiety for their pets.

A sonic evaluation can be taken in your veterinary office, grooming facility or boarding kennel. Note the noise level surrounding the animals. You may be surprised to discover how often a dog or cat jumps when a cage door is slammed, the clippers are running, or the vacuum is sweeping up hair. Staff members yelling across the room, and intercoms blaring can elicit continual orienting responses by your patients. Be aware of the environment your patients are being exposed to, especially when they are recovering from surgery or a severe illness.

Most veterinary offices play music that suits the staff, however, many of us don't consider the effect on our patients. A noisy kennel can easily compound the stress of an already anxious boarder. Lastly, you may want to consider what effect an unhealthy sonic environment has on staff and work productivity. Creating an environment that supports well-being, rather than causing discord, may be a very cost-effective management decision.

Psychoacoustic principles have been well established in humans. Multiple studies on the effect of music on animals have been published, with a recent study done by Wells et al showing that classical music is the preferred calming sound source in dog shelters. Anectodal evidence from concert pianist Lisa Spector revealed that certain pieces of classical music produced a difference in the behavior of dogs. For example, when she played certain pieces, a highly energized puppy would calm down within one minute and stay that way for the duration of her playing. When caring for an ailing, elderly dog, the sound of wind caused stress. Lisa noticed that when she introduced piano into the environment, the dog relaxed.

What is not known, however, is whether the same human oriented psychoacoustic principles of resonance, entrainment, and pattern identification apply to domesticated animals. While domesticated animals possess more highly tuned hearing than their human guardian's, we do not know if their cerebral function allows them to recognize sonic relationships (i.e., intervals, harmonies and fast or slow external rhythms).

Original Research

The purpose of our study was to investigate multiple types of classical music on the behavior of dogs in kennel and home environments. The music was chosen and arranged according to the principles of entrainment and harmonic complexity. Although brain wave frequencies are consistent among breeds of dogs, heart rates vary according to size. The tempos used in this project were based on an average size dog. The project was divided into two pilot studies:

Pilot I

The purpose of Pilot I was to test four types of classical music to determine if entrainment and pattern identification took place:

R1 – solo piano with simplified arrangements at 50-70 beats per minute

R2 – piano trio with simplified arrangements at 50-70 beats per minute

T3 – solo piano with more complex arrangements at 60-80 beats per minute

T4 – piano trio with more complex arrangements at 60-80 beats per minute

These CDs were tested in home and group environments. Kennels included 3 humane societies, 2 boarding facilities, 2 guide dog training facilities and 1 veterinary hospital. The guardians and kennel help were instructed to start the music, then fill out a questionnaire at 30 minutes. In the home setting, they were asked to rate whether their dog stayed the same, became more anxious, became calmer or went to sleep. In the kennel setting, they reported the percentage of dogs in that group that exhibited those behaviors. They were requested to continue playing the music for the remainder of the hour. This was repeated 10 days in a row for each CD. The sequence of the CDs was randomly varied, to avoid being played in the same order at each facility.

Kennel Observation

Results for the kennel environment show some interesting trends. Despite the stress of a kennel environment, upwards of 70% of the dogs became calmer with the R1 and R2 discs. (There was one outlier in the group day 4-10 data. If that is removed, the overall calm percentage approaches the 78% mark.) Most of the groups show only a 50% range with the T3 disc.

Home observation

The same pattern seen in the kennel environment is far more visible in the home group, although the numbers of subjects was much smaller. The R1 disc in this environment showed an overall average of 85% becoming calm, and over half went to sleep. Perhaps the lower stress in the home vs. the kennel environment was a factor. R2 percentages, however, were not as high. Once again, T3 produced values in the 50% range.

Pilot I summary

The purpose of Pilot I was determine the efficacy of external rhythm and pattern identification on canines in the kennel and home environment. Four types of classical music were tested. The results suggest that all classical music does not have the same effect on behavior in dogs. Varying the instrumentation and tempo can produce marked differences in results, with slower tempos and simpler sounds have a greater calming effect.

Pilot II

The purpose of Pilot II was to determine if music arranged according to psychoacoustic principles would have an effect on specific anxiety issues in dogs, such as fear of thunderstorms, separation and fireworks. Upon review of the data from Pilot I, it was decided that R1 CD showed the most consistent results for calming dogs in both the kennel and home environment. Because many guardians turn the radio on for their pets when they leave home or when a thunderstorm is approaching, another CD of standard classical music (C1) was chosen for comparison. C1 CD was a compilation of frequently played music that had not been psychoacoustically arranged. The music was taken from the play list of a San Francisco classical radio station.

Ten dogs with anxiety were entered into Pilot II. Their specific anxieties were as follows:

Other dogs or children/strangers in the environment (3 dogs)

Visitors in the home environment

Thunderstorms

Riding in the car

Excessive need for attention – pawing at guardian

Separation anxiety (2 dogs)

Fireworks

The guardians were asked to play the music for 20 minutes, then rate if the music caused a reduction in duration or intensity of 15 behaviors associated with anxiety. These included panting, pacing, trembling, barking, shining, drooling, hiding and general anxiety as perceived by the owner. Ratings were based on a scale of 1 to 5, with 1 being strongly disagree, 2 disagree, 3 neutral, 4 agree and 5 strongly agree. They were instructed to circle not applicable (NA) if their dog did not exhibit a particular behavior.

Results

When adding up all the behaviors elicited by the 10 dogs, a total of 60 behaviors were recorded for R1 CD and 59 for C1 CD. R1 CD results revealed that 10% were recorded as strongly disagree or disagree, 20% were neutral and 70% were agree or strongly agree. C1 CD results showed that owners scored strongly disagree or disagree for 34% of the behaviors, 31% of behaviors were scored neutral, and only 36% were scored as agree or strongly agree.

The guardians were also asked if their pet laid down or went to sleep, and if they themselves felt calmer while listening to the music. Interestingly, 60% of the guardians felt calmer when R1 was played, but only 20% of them reported a calming effect with C1. As for lying down or sleeping, there were no differences between the two CDs. Most of the dogs laid down (8 for R1 and 9 for C1), but only 1 in each group went to sleep. These results suggest that any classical music will help a dog calm enough to lie down, but R1 CD addresses specific anxiety behaviors more effectively.

Pilot II Summary

70% of anxiety behaviors were reduced with R1 CD and 36% of anxiety behaviors were reduced with C1 CD. Both CDs calmed the dogs enough to make them lay down, however, it appears that the R1 music, with slower tempos and simple arrangements and sounds, is more effective in reducing anxiety.

Future Projects

Further studies would be helpful in ascertaining the mechanisms of entrainment with dogs. Continuous monitoring of heart and respiration rates and brain waves would allow us to understand the physiologic effects of music arranged according to psychoacoustic principles. Also, understanding whether there are differences in breed and species size would be clinically relevant. Pets such as cats, pocket pets (hamster, guinea pigs, etc) and horses may not respond in the same manner as dogs. This work may be useful in reducing stress in farm animals, which has repercussions that extend beyond behavior to public health.