Month: January 2023

Does My Ultrasonic Humidifier Hurt My Dog’s Ears?

Does My Ultrasonic Humidifier Hurt My Dog’s Ears?

ultrasonic humidifier with a white base and a clear blue plastic top

No, Your Ultrasonic Humidifier Doesn’t Hurt Your Dog’s Ears

The mechanism in an ultrasonic humidifier has a frequency much too high for dogs to hear. Ultrasonic humidifiers use frequencies ranging from approximately 1,600,000 Hz to 3,000,000 Hz. Dogs can hear up to 45,000 Hz. The sound produced by this very high-frequency device is profoundly out of hearing range for both dogs and humans.

Although sounds outside our hearing range can in some cases damage humans’ ears and possibly dogs’, I’ve seen this documented only for extremely low-frequency sounds (Kugler et al., 2014), not high.

Humans tend to assign a glamour around the fact the dogs can hear in a higher frequency range than we can. Maybe it’s mysterious because we don’t know what’s going on up there? We feel like anything could be happening since we can’t hear it! Whatever the reason, there is a ton of misinformation online about dogs’ responses to high-frequency noises. I’m tackling this myth about ultrasonic humidifiers first.

This post includes a lot of discussion of sound frequency; if you need a review of the concept, check out my post that includes an explanation. Also, you will see me writing out the numerals for frequencies in this piece rather than using the common scientific shorthand. For instance, I will write 1,600,000 Hz instead of 1.6 MHz. I want the magnitude of the numbers to be clear to all readers.

What Is Ultrasound and Can Dogs Hear It?

Ultrasound is defined as sound higher than 20,000 Hz. That base frequency is the approximate upper limit of human hearing.

But the term “ultrasound” has two common usages, and this causes confusion.

One usage is to refer to frequencies in the range immediately above the limit of human hearing. Sometimes an upper limit of this “lower” ultrasound is given as 25,000 Hz or 40,000 Hz. Dogs can hear in this range. I’ve also seen “low-frequency ultrasound” defined as up to 100,000 Hz.

That’s the first usage, and you can see it’s a little fuzzy.

The other usage of “ultrasound” refers to very high-frequency sound in the millions of Herz. These are the frequencies of ultrasound often used in medicine and industry.

These two usages often result in people worrying that dogs can hear up in the millions of Herz range, but they can’t.

Dogs with normal hearing can definitely hear sounds above 20,000 Hz, as in the first usage. Their hearing range tops out at about 40,000–45,000 Hz (Heffner, 1983). They can’t even come close to hearing sound with frequencies of a million Herz.

For a complete comparison of dogs’ hearing with that of humans, check out my blog post on the topic.

What Frequencies Do Ultrasonic Humidifiers Use?

ultrasonic humidifier with a white base and a clear blue plastic top with mist coming out of it

Ultrasonic humidifiers have a vibrating plate that creates ultrasonic waves ranging from 1,600,000 to 3,000,000 Hz (Al-Jumaily & Meshkinzar, 2017; Yao et al., 2019; Yao, 2016).

The function of ultrasound in humidifiers is to atomize the water in the tank into tiny droplets, creating a mist.

In general, the higher the frequency of the ultrasonic vibration, the smaller the droplets produced.

To reiterate, the ultrasound frequencies used by humidifiers are far too high for dogs to hear. A humidifier using a 1,600,000 Hz mechanism is operating at a frequency 36 times the upper limit of dogs’ hearing.

We are not even talking about the same ballpark.

Can Ultrasound Cause Damage to Dogs’ Ears?

It could, in the lower range of ultrasound I’ve discussed. But such a sound would rarely be encountered, and it wouldn’t be coming from a humidifier.

The important factors in causing ear damage are the sound pressure level (SPL) experienced by the individual and the duration—not the frequency. So higher frequencies are not intrinsically worse for dogs’ ears. A noise in the ultrasound range would need to be very loud to cause damage, just as is the case in other ranges of the sound spectrum.

Ultrasound in the lower range can also be damaging if it is focused by a medical or industrial instrument. For example, ultrasound around 25,000 Hz is finely targeted to break up kidney stones in humans. This is a frequency dogs can hear, but what are the odds of a direct, focused exposure to a dog’s ear?

Neither of these cases apply to humidifiers because of the difference in frequency range, and would rarely be encountered by humans or dogs in day-to-day life.

I haven’t found any literature indicating that ultrasound in the millions of Herz would cause ear damage to dogs or humans. I’ll be looking further to make sure, but my guess is that it’s not something to worry about, for two reasons. First, it would be rare to encounter a loud sound source in that frequency range. That takes some extremely specialized equipment. Second, sound waves at ultra-high frequencies dissipate and attenuate (roughly, they scatter and get quieter) very fast as they travel through air.

In a future post, I will review possible sources of psychological irritation from ultrasound. There are indeed sounds in the lower ultrasound range that your dog might hear and find irritating or scary even though they don’t damage his ears. I’ll discuss ways to detect sounds in this range in your home. I’m not including these topics here because they don’t relate to the ultrasound frequencies humidifiers use.

tan dog wearing hearing protection: Mutt Muffs

Consumer Cautions about Ultrasonic Humidifiers

If you read up on the safety of ultrasonic humidifiers, you will find lots of cautions about the fact that they can aerosolize mold, bacteria, and even minerals in water (Environmental Protection Agency, 1991; Yao et al., 2019; Dietrich, Yao, & Gallagher, 2022). These cautions actually made me start cleaning out my humidifier more often and I plan to get distilled water to use instead of tap water.

In the safety instructions, you will not find any cautions about the ultrasounic waves.

Why Did I Even Write about This?

Search the title of this post in Google and you’ll see. There is so much misinformation online about dogs and high frequencies. This post is just a start. Next, I’ll be discussing the erroneous belief that somehow, all sounds with frequencies in the upper half of dogs’ hearing range are intrinsically annoying, painful, or harmful to them.

Copyright 2023 Eileen Anderson

Other Dogs and Sound Posts

Impulse Sounds and the Startle Reflex: Why Some Dogs Fear the Clicker Sound

How to Soundproof a Dog Crate

• Review of Pawnix Sound Cancelling Headphones for Dogs: Unlikely to Work as Described

• My webinar on dogs and sound: Sound Decisions

• How to Tone Down That Plastic Collar Click (and Why)

• How I Taught My Dog to Love the Sound of Velcro

• Using Sound Masking to Protect Your Dog from Loud, Scary Sounds

• Are Dogs Ever Irritated by Sights, Sounds, or Smells?

• 6 Ways to Prepare Your Dog for Fireworks

References

Al-Jumaily, A. M., & Meshkinzar, A. (2017). On the development of focused ultrasound liquid atomizers. Advances in Acoustics and Vibration2017.

Dietrich, A. M., Yao, W., & Gallagher, D. L. (2022). Exposure at the indoor water–air interface: Fill water constituents and the consequent air emissions from ultrasonic humidifiers: A systematic review. Indoor air32(11), e13129.

Environmental Protection Agency. (1991). Indoor Air Facts No. 8: use and care of home humidifiers.

Heffner, H. E. (1983). Hearing in large and small dogs: Absolute thresholds and size of the tympanic membrane. Behavioral Neuroscience97(2), 310.

Kugler, K., Wiegrebe, L., Grothe, B., Kössl, M., Gürkov, R., Krause, E., & Drexl, M. (2014). Low-frequency sound affects active micromechanics in the human inner ear. Royal Society Open Science1(2), 140166.

Yao, Y. (2016). Research and applications of ultrasound in HVAC field: A review. Renewable and Sustainable Energy Reviews58, 52-68.

Yao, W., Gallagher, D. L., Marr, L. C., & Dietrich, A. M. (2019). Emission of iron and aluminum oxide particles from ultrasonic humidifiers and potential for inhalation. Water research164, 114899.

When a Dog Suffers a Trauma

When a Dog Suffers a Trauma

The scene is the back interior of a car. There is a bowl of cat food in the foreground. In the back is a dog crate with a distressed brown dog looking away.

Here’s a photo that breaks my heart. Clara the bold, refusing to leave her car crate, even to eat some cat food.

This is what happened.

Early in December, I took Lewis and Clara to the house my sister is going to move into so they could mess around while I cleaned house. It was raining and dreary. There were leaves layered on the lawn and on the steep driveway.

Clara always jumps into the car on her own, but I help her get out. It’s the same routine we’ve had since she was a little pup. After I open her crate door, she comes to the back driver’s side door where I am standing and walks into my outstretched arms, and I lower her down. We do this even though she is 45 pounds, because my SUV floor (on top of the folded seats) is too high for her to jump down from safely, especially at her age.

A red Subaru Outback is parked on an inclined concrete driveway covered with leaves. An arrow points to an area on the concrete just below the back door on the driver's side.
The arrow marks the place I put down Clara after I lifted her from the car. The driveway was wet as well as leafy.

So on this day, she came out of her crate and came to the car door. I beckoned, and she stepped into my arms. I lifted her down. When I put her down on the wet driveway, she slipped and fell onto her side. She didn’t appear to be injured, but the fall was traumatic. She scrambled up, jumped back into the car, and dove into her crate.

I coaxed her out, and she stood there with her back legs trembling, as she does when scared. I couldn’t tell for sure, but she seemed unhurt. Then she scooted back into her crate again and wouldn’t come out.

Clara used to retreat to a crate as a puppy when she was scared or overwhelmed.

Coaxing Her Out of the Crate

I drove back home with both dogs (Lewis had never gotten out of his crate). When I got into the garage, I opened Clara’s crate door, but she wouldn’t come out. I let Lewis out and took him into the house, closing the car door before we went. I didn’t want Clara to try to get out on her own in case she ventured out of the crate.

I returned to the car and tried to coax Clara out. She wasn’t having any of it. She crouched in her crate, looking petrified. I got ahold of her collar, but she was a dead weight, and I didn’t want to resort to force in any case.

I went in the house and came back with two bowls of cat food. The ultimate treat. I planned to put one bowl near her crate, and another on the floor outside the car.

The scene is the back interior of a car. There is a bowl of cat food in the foreground. In the back is a dog crate with a distressed brown dog lying in the crate, backed up from the opening, looking at the camera and ignoring the food.

I set a bowl down in front and a little to the side of her crate. She didn’t budge. I had to hold back tears. She wouldn’t come out for cat food. I left for a bit, shutting the car door. When I came back, she was still in her crate, the cat food untouched.

I left again, for a little longer. When I came back, she was in her crate, but the cat food was gone. She had come out and gone back in again. I was simultaneously relieved and heartbroken. She would come out and eat when I was gone, but not when I was there. Ask anyone who takes in fearful foster dogs. That’s how she was acting, creeping out to eat the food when I was gone, then scuttling back into her safe place. I appeared to be associated with the trauma.

I brought cat food again and left it. Each time when I came back, she had eaten it. She started hanging out in the front of her crate with slightly more relaxed body language. Finally, on about my fifth try, she came out to eat the cat food while I was still there. As desperate as I was to get her out, I didn’t grab her. I let her have the cat food, then she went back into her crate, as I figured she would. This gave me confidence to proceed, though.

I needed a new way to help her out of the car. She didn’t know how to do it on her own by taking a step on the floor of the car, and I was sure she wouldn’t walk into my arms. I decided to use my Klimb, a sturdy, low platform designed for dog activities, as a landing pad. I opened the rear hatch, took Lewis’ crate out, and put the Klimb next to the back of the car. Clara has experience Jumping down onto the Klimb already. I bought it as a step off my bed for disabled Zani, and Clara has used it as well. We do all sorts of training and husbandry on the Klimb, too. It is conditioned as a happy and safe place.

I set up the Klimb. I put the bowl of cat food down near Clara’s crate and she came out and ate. As she did that, I again refrained from grabbing her, but I closed the crate door so she couldn’t hurry back in. She tried a couple of times to get back in her crate, then she walked to the rear where I was waiting. I tapped the Klimb and cued her to jump down on it, and she did! I had yet another bowl of cat food ready. She gobbled it happily, jumped off the Klimb, and went into the house. The timing was great. My partner Ruth had just finished having lunch and had saved a couple of pieces of hot dog for Clara, as she always does. Clara slipped straight into one of her happy routines.

Back in the House

Clara didn’t act scared of me. What a relief—I had been fearing the worst. I have always been her safest anchor in the world. I was safe again, outside the car situation. I had no idea how she would react when we tried the car again.

Over the next couple of days, Clara got excited and asked to come along every time I went somewhere, which made me hopeful.

The traumatized reaction was atypical for Clara. She is physically bold and has never been afraid of objects or unstable surfaces. I was deeply upset by this development. I wanted and needed to help her feel better about exiting the car. Riding in the car is the doorway to lots of enrichment and fun for her, besides being a necessary life skill.

I have seen this kind of large fear response to an event only a couple of times with dogs, and I have learned to take it seriously. I needed to make a careful plan. It’s human nature to minimize this kind of thing in our minds, to assume the dog will “get over it.” It would have been natural for me to try the next day to “see if she would get out of the car the normal way.” I didn’t. I might have tried to change the situation a little, go somewhere different with a better landing area, and assume Clara “would understand that this was different and wouldn’t be scared anymore.” But I’ve finally learned that fear doesn’t work like that. I fought my impulses and made a plan that changed the picture a lot for Clara, because who knew what part of the situation her fear had already generalized to?

Addressing the Fear

The view is through the open rear hatch of a Subaru. There are two dog crates with a Klimb dog platform fitting vertically between them.
Klimb between crates: the front bottom leg is removed

I successfully rehabilitated Clara’s fear and she can again exit the car.

I abandoned the old method of lifting her down. Not only was it now associated with her fall, but I have a shoulder problem and the process causes me pain, too.

With encouragement from Marge Rogers, I figured out that I could fit the Klimb in my car along with both crates. It fits vertically between them if I unscrew one of the bottom legs. I purchased the Klimb’s custom nonslip cover. I had been using a square of yoga mat, but wanted the extra security of the better fit.

Our new method was the same way I got her out that first day: step down onto the Klimb, then down to the ground. But I didn’t want to always have to get her out the back. I needed to have the option to put the Klimb next to a door as well.

Here is the plan I made and carried out. You can see most of it in the video embedded below.

1. With Lewis’ crate removed, I cued Clara to get into and out of the car via the Klimb placed in back. I reinforced generously, especially for coming out. I used either spray cheese or Stella and Chewy’s dehydrated raw food for every step.
2. Next, I cued Clara to get into and out of the car via the Klimb placed next to the passenger side door, which she has never used before.
3. First with Lewis’ crate removed, then with it present, I cued Clara to get into and out of the car via the Klimb placed next to the driver’s side. This is her lifelong exit location from the car, and was the most likely to have fear attached to it, so we worked up to doing it last.
4. Finally, we took it on the road. We went somewhere fun. She was happy to jump out via the platform.

A Klimb dog platform is sitting on the level part of a mostly inclined driveway next to a red Subaru. The Klimb is placed next to the back door on the driver's side as a step for dogs when they get out of the car.
The Klimb goes flush next to the car and the car door opens over it. Perfect!

Designing a Training Plan for One Dog

I tailored this plan with Clara’s history and capabilities in mind. I’m not suggesting this as a method for anyone else.

Luckily, Clara was not scared of getting into the car, being in the car, or riding in the car. Just getting out. So I needed to take an operant approach. I would have made a different plan (and likely a longer one) if either of the latter two had scared her. I would have used a classical conditioning-based method.

Here are some reasons why my approach worked for Clara, but might have been a bad idea for some dogs.

1. It involved jumping onto a small surface. It would have been a different and longer process if Clara hadn’t already been comfortable with the Klimb. She has had lots of good experiences on there, including jumping down onto it as well as up. She grew up in an agility household and got plenty of practice jumping on and off a variety of things.
2. My method involved a bit of luring or targeting as I beckoned her onto the Klimb the first few times. For some dogs, that would have been too much pressure. It’s not a good idea to lure a dog toward something that scares them. Again, Clara’s comfortable with the Klimb.
3. The area behind my car in the garage was a tight place to work. You’ll notice it in the video. Clara was exiting the car straight at the closed garage door, which was very close. She had to jump down and immediately halt her forward motion. A bigger dog, or a dog lacking her physical ability might have had a hard time. But she coped fine. I made this choice because leaving the garage door open would’ve had its own set of problems.

For those who would like some more general instructions for a dog who may not be used to getting onto a stool or platform, here is a video by the wonderful trainer Donna Hill with step-by-step instructions on teaching a dog to enter and exit a car using a step stool.

Video of Training Steps for Getting Out of the Car

The great thing about a dog who loves to go places in the car is that going to a fun location becomes the large, terminal reinforcer. I’m still using higher value reinforcers for moving on and off the platform, but I’m gradually fading them to lower value as she becomes fluent with this new system. You can see in the video that she is interested in the environment as soon as she exits the car.

Might Clara’s Reaction Be Related to Cushing’s Disease?

Clara was diagnosed with Cushing’s disease last May (2022). Her original symptom was extreme hunger. Her case is mild so far, and she is not on medication yet. But over the summer, she started exhibiting some weird fears.

I suspect those fears, and her high-magnitude response to a onetime fall, are related to the Cushing’s. This disease causes dogs to have an overabundance of cortisol in their system. Not a great situation for a dog with fears and who had such a hard start in life. Her recent anxiety and fears could also be early symptoms of canine cognitive dysfunction. Cushing’s may raise the likelihood of that condition as well (da Silva, 2021).

My vet and I are trialing some meds. The thought of Clara having added fear and stress in her life makes me feel sick. I’ll do anything in my power to help her. In the meantime, I’m relieved Clara is comfortable getting out of the car again. We dodged a bullet. I’ll be keeping the Klimb in there for good.

Reference

da Silva, C. C., Cavalcante, I., de Carvalho, G. L. C., & Pöppl, Á. G. (2021). Cognitive dysfunction severity evaluation in dogs with naturally-occurring Cushing´s syndrome: A matched case-control study. Journal of Veterinary Behavior, 46, 74-78.

Copyright 2023 Eileen Anderson

Photos copyright Eileen Anderson. The photos of Clara frightened in the car were digitally altered by a Photoshop specialist to remove a whole lot of white dog hair that was sticking to the fabric on the back of the rear seats. I don’t mind telling you about it, but I’m glad I didn’t have to let you see it!

Copyright 2021 Eileen Anderson All Rights Reserved By accessing this site you agree to the Terms of Service.
Terms of Service: You may view and link to this content. You may share it by posting the URL. Scraping and/or copying and pasting content from this site on other sites or publications without written permission is forbidden.