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


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

Apr 01, 2010

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.