How do horses respond to different human voices? When we are grooming a horse and talking softly, does the horse understand what we are communicating? Do they pick up on the way our voice sounds and not just our words?
Most horse owners will tell you that their horses know when they’re being scolded or when they’re being praised based on tone. Some will even say their horse has a preference for a high- or low-pitched voice. But is there any proof?
Jill, an 11-year-old Percheron mare, has her turn in the round pen.
Dr. Katrina Merkies at the University of Guelph in Ontario, Canada and Agrocampus Rennes in France performed a study to find out if different manners of speaking in humans made any difference in horse behavior. Their subjects were eight draft horses. Each horse was turned loose in a round pen for five minutes while researchers documented baseline statistics about their gait, head height, and ear and body position in relation to a human standing by the pen. The horses’ heart rates were also measured.
Horse Talk: Do you know how to calculate a horse’s heart rate? Count the number of beats in 15 seconds, then multiply by 4 to get beats per minute (bpm).
Data was collected in 5-second intervals during the control and baseline treatments, and in 1-second intervals for the duration of the sound treatments.
Horse wearing Heart Rate Monitor (HRM).
1. How many times was data recorded per minute in the 5 minute baseline period?
2. How many times was data recorded per minute during the sound treatments?
3. How many times was data recorded over the entire 5 minute baseline period?
4. If you wanted to calculate the mean heart rate for each horse during the 5 minute baseline period, how would you do this?
Once those measurements had been recorded to determine a baseline for each horse, 10 seconds of a recorded human voice was played while a human familiar to them was positioned near the pen. The voices were classified as a pleasant voice, low tone; pleasant voice, high tone; stern voice low tone; stern voice, high tone.
When no human or sound was present, the horses tended to keep their head at the lowest position, and all of the subjects raised their head when the human or sound was present. The voices categorized as pleasant was more likely to cause the horses to position their bodies toward the human.
The greatest effect on heart rate occurred when the stern, low voice was played. The chart to the right shows the heart rate range for the 5 minute baseline period for each horse and the heart rate range exhibited by each horse when the stern-low voice was broadcast.
You be the scientist!
The normal resting heart rate for an adult horse is 32 to 44 bpm.
5. Which horse seemed the most relaxed during the baseline period?
6. Which horse seemed the least comfortable during the baseline period in the round pen?
Derby, the only Clydesdale horse participating in the study.
7. Which horse showed the greatest stress when listening the the stern-low voice?
8. Which horse showed the least stress?
The researchers concluded that the heart rate elevation caused by the stern-low voice, may indicate that horses recognize a scolding tone.
You can see how varied the heart rates were for each of the horses in the study. This is why horse owners are taught to know their horse’s individual normal resting heart rate. Like people, some horses are more easy going and relaxed than other horses. This will show up in their heart rates.
Would you like to watch a video of one of the sessions?
“We’ve shown that horses do in fact display different physiological and behavioural responses to different tones and voice,” said Katrina Merkies of the University of Guelph. “So horses are able to discriminate between different tones or qualities of voice. However, it’s not clear if the horse is interpreting or responding to the tone of voice alone, or if it’s looked at in combination-both tone of voice and the human’s body language. Which is the more obvious clue to the horse? That certainly warrants further study.”
Calculating a horse’s heart rate is covered in detail in the Level 1 workbook.
Think about the time you spend with horses. How might different experiences effect a horse’s heart rate? What happens to your horse’s heart rate when she is loaded onto a trailer? Is she stressed or is it no big deal? What about riding in a show? Does your horse get as nervous as you do? Conduct your own research and share it with everyone here on Horse Lover’s Math!
Do Horses Understand Our Tone of Voice? Answers
1. How many times was data recorded per minute in the 5 minute baseline period?
Answer: There are 60 seconds in 1 minute. 60 ÷ 5 = 12. Data was recorded 12 times per minute during the baseline period.
2. How many times was data recorded per minute during the sound treatments?
Answer: Data was recorded 60 times per minute during sound treatments.
3. How many times was data recorded over the entire 5 minute baseline period?
Answer – Using the answer to question 1, we know data was recorded 12 times per minute.
Step 2: 12 (number of times data was recorded per minute) x 5 (minutes) = 60. Data was recorded 60 times in the 5 minutes.
4. If you wanted to calculate the mean heart rate for each horse during this baseline period, how would you do this?
Answer: Add up each of the recorded heart rates and divide by 60.
Math Talk – Calculating an average: add up all the numbers, then divide by how many numbers there are.
5. Which horse seemed the most relaxed during the baseline period?
Answer: Billy. His heart rate fell mostly within the normal range for an adult horse with the high end only 5 bpm outside the normal resting rate.
6. Which horse seemed the least comfortable during the baseline period in the round pen?
Answer: Derby, his heart rate range was the highest.
7. Which horse showed the greatest stress when listening the the stern-low voice?
Answer: Superman. He had the greatest increase in heart rate, jumping from 57 bpm at the high end to 107 bpm.
8. Which horse showed the least stress?
Answer: Billy. His heart rate range remained the same.
Common Core:
4.OA.A.3 – Solve multistep word problems posed with whole numbers and having whole-number answers using the four operations
4.MD.A – Convert time units
4.MD.B Represent and interpret data.
5.MD.B – Represent and interpret data.
6.SP.A.3 – Calculate mean, median, mode, and range
Photos:
All photos courtesy of Dr. Katrina Merkies.
