What’s That Humming Noise in My Hotel Room? Can I Get Rid of It?

Have you ever experienced a low-frequency humming noise in your house that kept you awake?

On a recent trip to Vietnam, I had one of these weird sounds in a hotel room.

I checked into the hotel and almost immediately noticed a humming noise in my room. Being the low-frequency noise “hater” I am, I thought for a moment: “OMG, I won’t be able to sleep well in here.”

hotel room low frequency humming noise

Then, however, I decided to make an effort to get rid of the hum.

It was louder close to the headboard wall and relatively more quiet at the foot end of the bed.

Touching the wall, I could feel the vibrations. The sound was real.

I pondered for a moment what might be causing it: Perhaps one of the AC compressors was on its way out or improperly mounted to an outside wall?

Looking out of the window I couldn’t find anything obvious though.

At the end of the day, it didn’t matter. I wasn’t going to make this hotel refit AC compressors. (While the staff was very friendly, I was barely able to communicate with them.)

So I focused on measuring and recording the humming noise and trying to get rid of it.

Close to the walls, I measured the hum at over 60 decibels (in the 63-Hz band), sometimes reaching >65 dB.


The room was generally quiet, otherwise I would perhaps only have noticed that noise at night.

To better pinpoint the dominant frequencies, I recorded it and looked at its frequency spectrum:

It turned out to be humming noise peaking at 50 Hz. (Note: Electricity in Vietnam is 220V/50 Hz. In the U.S., it is 110V/60 Hz.)

50-Hz Hum in a quiet room

This is what the microphone picked up close to the wall:


Would you be able to sleep peacefully with that kind of noise?

“OK,” I thought. How do I get rid of this noise?

First, I tried my Bose QC35 noise cancelling headphones.

That hum wasn’t quiet. Would they be able to make it disappear?

Well, I put on the QC35, turned them on, and—they did a fabulous job.

Despite best efforts, I couldn’t make out the noise anymore. It was gone.

Taking the headphones off, the obnoxious hum immediately came back.

So yes, these noise cancellers pushed my hum below the threshold of hearing.

Bose 1: Hum 0.

I had a solution. But, while I would definitely sleep with these headphones if necessary, I am a side sleeper, and I hadn’t even brought my special pillow.

Would earplugs work against the humming noise?

I had two pairs with me: Moldex Purafit (NRR-33)—one of my favorite foam earplugs for sleeping and Mack’s Flightguard (NRR-26) —reusable earplugs that are designed to block noise and help with airplane pressure changes.


Earplugs with a U.S. noise reduction rating (NRR) have to be tested at several frequency bands for their ability to reduce noise. Unfortunately, the relevant standard only mandates testing down to the 125 Hz band.

And companies in the U.S. usually don’t publish any results that go below the 125-Hz octave band.

So you can’t really tell from the NRR how good earplugs are going to be with a 50-Hz hum (or something even lower-pitched).

Well, I tried both types of earplugs.

I rolled up my Purafit and put them in at my standard depth (which is pretty deep for best low frequency noise reduction).

They too made the hum disappear.  If I listened very carefully, there was perhaps a trace left, but I wasn’t sure whether that was my brain imagining it. In any case, I didn’t see how that could keep me from sleeping.

Then I tried Mack’s Flightguard earplugs, and they also worked very well against that low-frequency noise. Subjectively, I couldn’t tell which earplugs worked better.

But the Flightguard have a rigid stem, which makes them less comfortable for side sleeping.

And they also don’t perform quite as well as the Purafit against other noises, so the foam earplugs were going to be my noise fighters for the night.

I slept well that night and didn’t notice any humming noise. Taking out the earplugs in the morning, the hum returned, but it had lost its “psychological teeth.”

So in conclusion: Deeply inserted Moldex Purafit foam earplugs, Mack’s Flightguard earplugs, and Bose QC35 headphones all worked against that 50-Hz hum.

I also tried a white noise machine and a pair of earmuffs against the humming noise.

I often travel with a white noise machine because I find it great for masking environmental noise in general and often use it together with foam earplugs.

The white noise machine by itself (without wearing the earplugs) wasn’t able to mask the humming noise.

This didn’t come as a surprise as the relatively small speakers can’t output pink noise or a fan masking sound with decent power at 50 Hz. And even if the machine was large enough to do the job, I am not sure I would prefer that noise over the hum.

So, while my white noise machine is of great help against mid-and-high-frequency noise, it doesn’t work against a 50-Hz hum.

I also tried a pair of NRR-24 earmuffs, which have decent attenuation at 125 Hz (the lowest frequency they are tested for). The earmuffs did reduce the humming noise, but it was still clearly present. And because the remainder of the environmental noise was very effectively muffled, it was perhaps even easier to focus on it.

Measuring disturbing low-frequency noise with a sound level meter

Many economical digital sound level meters only display dBA (=a-weighted decibels).

However, to account for the decreased sensitivity of human hearing at lower frequencies (at lower volumes), in a-weighting, sound levels for frequencies <1000 Hz are given significant downward corrections.

That is a problem if you want to detect low-frequency noise.

 31.5 Hz63 Hz125 Hz250 Hz500 Hz1000 HZ2000 Hz4000 Hz8000 Hz
A-Weighting Correction (dB)-39.4-26.2-16.1-8.6-3.201.21-1.1
C-Weighting Correction (dB)-3.0-0.8-0.2000-0.2-0.8-3.0

As a consequence, while clearly annoying me, the humming noise I experienced in my hotel room would lead to very little difference on a sound level meter displaying dBA.

The overall sound level in the room at the time of the recording was 35.7 dBA; I would say this is an acceptable noise level for a bedroom at 11:30 am, and just seeing that number I wouldn’t expect any problems.

Sound level meters that can be switched to dBC (c-weighting) or dBZ (no weighting), or additionally show un-weighted octave bands are better equipped to detect lower frequencies in a room.

NIOSH’s sound level meter app can also be switched between dBA and dBC.

Also, very low-frequency hums may peak below the measuring range of economical sound level meters (and smartphone apps). So the humming noise you perceive may be real, even if your sound level meter doesn’t show it.


At times you may not be able to find the source of humming noise that bothers you.

Even if it is at a relatively low frequency, like this 50-Hz hum, a good pair of foam earplugs may be all that is needed to save your sleep.


5 thoughts on “What’s That Humming Noise in My Hotel Room? Can I Get Rid of It?”

  1. I had a similar experience in Vietnam. Spent about ten minutes convincing staff I wasn’t crazy. They moved me to a room without the noise yay. Thanks for the excellent posts.

    • Hello Nicole,

      thank you for stopping by. Interesting that you experienced that too.
      I agree, it’s definitely best to avoid that kind of humming noise and change rooms whenever possible.

      As for me, I liked the challenge. And, people living in these dense urban apartments can’t easily move.
      Have a great day.

  2. I agree there’s lots to be learned. The noise in my case was due to a water pump on the roof sending vibrations through the wall by my headboard. Unfortunately, I had no ear plugs with me, so in the end I was glad to move rooms.

    I found it interesting to observe that the Vietnamese people seemed a lot less bothered by noise. Early morning there were all sorts of early morning delights that didn’t seem to bother anyone – Cockerels, children, loud exercise classes. For me it seemed liked that Vietnamese folk had a much higher tolerance to noise. Walking the streets of Hanoi were an assault on my senses (at times pleasant of course – smell of bun cha) but no one else seemed phased! It seemed like noisy was the norm.

    Thanks for the great posts.

  3. I have traveled to several motels priced at $100.00 or less in the past 4 years. All have had structural vibrations. Room decor has been acceptable to lovely but the noise and vibration has made stay virtually unbearable. Most recent [admin edit] lovely but no sleep. How do these businesses succeed with this pervasive problem? Buying ear plugs or Ear phones won’t stop the floor walls and bed from vibrating.

    • Hello Cassandra,

      Thank you for your feedback.

      Yes, vibrations that you feel in your bed (i.e., they are structurally conducted into your bed) will be almost impossible to get rid of. If you bed starts shaking…

      There are some remedies you can try:

      1. I have found myself moving beds away from walls so that the two are no longer directly connected. This can make a huge difference. I understand this isn’t always possible.

      2. For me, worst are vibrations conducted directly into the head.
      Sleeping on my back, which I don’t like all that much, has often helped. When my ears touch the pillow, I am much more sensitive to vibrations.

      3. A microbead pillow on top of the regular pillow can also help somewhat.

      4. Try sleeping with you head at the foot end of your bed.

      5. Finally, with low frequency noise, our senses can fool us: for example, at times we may think we feel truck rumble or humming, yet upon turning on noise cancelling headphones the “vibration” disappears or is greatly reduced.

      Ultimately, whenever possible, I vote with my feet and choose a different lodge during my next stopover.

      All the best.


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