Explain This Audio Illusion For Me

[easysurfer]

I've been seriously thinking about getting a new chamber vacuum sealer as the one I currently have I think runs too loud. While operating, if I'm not wearing ear protection the noise soon gives me a headache. It's so loud, I can even hear the machine running when I'm out in the hallway outside my condo unit.

I had an ah-ha moment as I have a decibel meter app on my phone. So as comparison, I decided to measure the noise of the chamber sealer in comparison to my old original Foodsaver.

I run the chamber sealer and measure, only about 68 decibels. Not that loud. I then measure the old Foodsaver at that is over 70 decibels. What gives? Is my mind playing tricks on me?

My ears can tolerate the old Foodsaver but not the chamber without ear protection. What gives?

My theories are:

1) the Foodsaver being a smaller machine, the noise is more concentrated so though higher decibel actually less noise overall

2) the issue isn't so much decibels as duration as the chamber runs about 30 seconds each time whereas the old Foodsaver runs about 10 seconds.

Your thoughts?

 

[joeea]

Do both sounds have the same pitch? Pitch matters when considering tolerance.

 

[easysurfer]

Do both sounds have the same pitch? Pitch matters when considering tolerance.

Different pitch. The old Foodsaver is more distinct. The Chamber is more like the hum of a pump (as the machine is a non-oil chamber sealer, which is louder than oiled ones).

 

[samclem]

There are several different units used to measure sound/noise. Some "decibel" scales are calibrated to closely match the response of the typical human ear, others are wildly different. I don't recall much more than that, but a search online (and through your app's documentation) should provide more info.

 

[Spock]

did you measure dB in the same location as you normal run the chamber?? The original location might have been resonating....

 

[Walt34]

There are several different units used to measure sound/noise. Some "decibel" scales are calibrated to closely match the response of the typical human ear, others are wildly different. I don't recall much more than that, but a search online (and through your app's documentation) should provide more info.

To make things worse, it gets a lot more complicated than that.

Back in the 1990's when I was active with radio control airplanes powered by small two-stroke engines, the club (and the county, which owned the flying site, a closed landfill) started getting noise complaints. Conveniently the club's president at the time was a sound engineer and we all learned a lot about sound, how it travels, and very importantly to the club, how it is perceived by the listener. It turns out that high-pitched sounds like those made by a model airplane are perceived as much more annoying than a lower-pitched sound made by a source such as a lawn mower that is even louder.

A couple of things to know: The dBa scale most commonly used is logarithmic in scale, so that a sound measured at 70 dBa is many, many times louder than one at 68 dBa. (I'm lousy at math so someone better at it can elaborate on that part.)

Your cell phone is a lousy sound meter. Even an el cheapo from Radio Shack or Harbor Freight will be lots more accurate because they are designed to be sound meters. Your cell phone is a terrible sound meter for the same reason that a cheap point 'n shoot camera will take better photos - it was designed to be a camera, not a phone.

This part might actually be useful. You're probably running your vacuum sealer on a kitchen counter which is acting like a drum and amplifying the sound from it. Try putting it on top of a stack of newspapers or a folded blanket to absorb the sound vibrations. You'll probably notice a huge difference. If it doesn't have rubber "feet" on it, buy some and try that. They're cheap and easily available.

 

[ERD50]

There are several different units used to measure sound/noise. Some "decibel" scales are calibrated to closely match the response of the typical human ear, others are wildly different. I don't recall much more than that, but a search online (and through your app's documentation) should provide more info.

That is "A" weighting, which mimics the human response.

But that is not even close to explaining this. You cannot describe a sound, and how annoying it is, with a single number representing its volume or spectrum.

Clearly, the sound of someone chewing with their mouth open would be drown out by a Symphony Orchestra at full crescendo. And the chewing would barely register even on a sensitive dB meter. But one is annoying, the other pleasing (to most).

Harmonics have a lot to do with it. A dissonant chord on a piano may have you leaving the room. A louder, but a consonant chord,may be pleasing.

-ERD50

 

[easysurfer]

did you measure dB in the same location as you normal run the chamber?? The original location might have been resonating....

Yes, I did.

 

[easysurfer]

A very interesting discussion.

I guess the sound isn't too loud at least as no one has knocked on my door and complained. I do run the machine during non quite hours like not before 10 am or later than 8 pm to not disturb any neighbors.

 

[NW-Bound]

That is "A" weighting, which mimics the human response.

But that is not even close to explaining this. You cannot describe a sound, and how annoying it is, with a single number representing its volume or spectrum.

Clearly, the sound of someone chewing with their mouth open would be drown out by a Symphony Orchestra at full crescendo. And the chewing would barely register even on a sensitive dB meter. But one is annoying, the other pleasing (to most).

Harmonics have a lot to do with it. A dissonant chord on a piano may have you leaving the room. A louder, but a consonant chord,may be pleasing.

-ERD50

+1

I can take a music CD, put it in my 75W/channel HiFi stereo and crank it up to the point the "overload" LED starts to blink. And it is so loud dust starts to fly off bookshelves, as I have high-efficiency loudspeakers at 98 dB/W. And it still sounds good.

Put the same CD in a boombox, and turn it to reasonably loud. With just 2-3W/channel power driving little 3" speakers, it can drive you bonkers. The distortion is just so bad.

And that's why people can go deaf listening to loud music. A portable boombox will not make you deaf, but will drive you insane.


PS. Many modern loudspeakers have efficiency of 88 dB/W. At 75W of drive, they sound as loud as my speakers at 7.5W, or 1/10 the power. A change in 10dB of sound level is a factor of 10X in power.

 

[easysurfer]

To make things worse, it gets a lot more complicated than that.

Back in the 1990's when I was active with radio control airplanes powered by small two-stroke engines, the club (and the county, which owned the flying site, a closed landfill) started getting noise complaints. Conveniently the club's president at the time was a sound engineer and we all learned a lot about sound, how it travels, and very importantly to the club, how it is perceived by the listener. It turns out that high-pitched sounds like those made by a model airplane are perceived as much more annoying than a lower-pitched sound made by a source such as a lawn mower that is even louder.

A couple of things to know: The dBa scale most commonly used is logarithmic in scale, so that a sound measured at 70 dBa is many, many times louder than one at 68 dBa. (I'm lousy at math so someone better at it can elaborate on that part.)

Your cell phone is a lousy sound meter. Even an el cheapo from Radio Shack or Harbor Freight will be lots more accurate because they are designed to be sound meters. Your cell phone is a terrible sound meter for the same reason that a cheap point 'n shoot camera will take better photos - it was designed to be a camera, not a phone.

This part might actually be useful. You're probably running your vacuum sealer on a kitchen counter which is acting like a drum and amplifying the sound from it. Try putting it on top of a stack of newspapers or a folded blanket to absorb the sound vibrations. You'll probably notice a huge difference. If it doesn't have rubber "feet" on it, buy some and try that. They're cheap and easily available.

Was thinking the same about the cell phone perhaps not being a good sound meter. Yes, vacuum sealer is on kitchen counter. There are rubber feet. The machine isn't vibrating on the counter as the thing (small for a chamber) weighs about 60 lbs.

 

[Walt34]

The machine isn't vibrating on the counter as the thing (small for a chamber) weighs about 60 lbs.

That it weighs about 60 lbs. is why it is transmitting the sound so well to the counter which in turn is vibrating. The rubber feet help, but they're already compressed somewhat by the weight. Do try the folded blanket, that should help, perhaps dramatically.

 

[easysurfer]

That it weighs about 60 lbs. is why it is transmitting the sound so well to the counter which in turn is vibrating. The rubber feet help, but they're already compressed somewhat by the weight. Do try the folded blanket, that should help, perhaps dramatically.

I didn't say anything about the sealer or counter vibrating. I think that was assumed by you .

Main reason for the noise is just maintenance free, non-oil chamber sealers make more noise than ones that require oil. If I had a large place (countertop not obstructed by overhanging cabinets) and could lift about an 85lb machine up to a counter or stand, I would have got a bigger machine.

Thanks for the suggestions, but I'll probably just stick to using ear protection as I still contemplate a quieter sealer as I really don't wish to have a blanket under the machine. I do understand where you are going though with the idea.

 

[easysurfer]

Just for grins, I didn't use a blanket but put under each foot one of those moving sliders to give some padding and raised the sealer up a tad. Then took my phone with the app to measure. Increased the decibel reading to about 72. Oh well ... just for grins .

 

[NW-Bound]

I've been seriously thinking about getting a new chamber vacuum sealer as the one I currently have I think runs too loud. While operating, if I'm not wearing ear protection the noise soon gives me a headache. It's so loud, I can even hear the machine running when I'm out in the hallway outside my condo unit.

I had an ah-ha moment as I have a decibel meter app on my phone. So as comparison, I decided to measure the noise of the chamber sealer in comparison to my old original Foodsaver.

I run the chamber sealer and measure, only about 68 decibels. Not that loud. I then measure the old Foodsaver at that is over 70 decibels. What gives? Is my mind playing tricks on me?
...

You gave me an idea, and I just did it.

I was about to change the oil in my car, and decided to switch from 5W30 oil to 10W40 because this car now has 170K miles on it. I expected to hear the difference with the thicker oil, and decided to quantify it.

Using an app on my smartphone, I measured the engine noise at 16" in front of the bumper. It's 80dB with the old oil and 78dB with the new oil. Ta dah!

Isn't science great?

PS. A difference of 2dB is small and would be easily missed. In fact, a difference of 1dB is barely perceptible to a human ear.

Yet, a difference of 3dB is twice the audio power. Yes, a factor of 2x.

 

[easysurfer]

You gave me an idea, and I just did it.

I was about to change the oil in my car, and decided to switch from 5W30 oil to 10W40 because this car now has 170K miles on it. I expected to hear the difference with the thicker oil, and decided to quantify it.

Using an app on my smartphone, I measured the engine noise at 16" in front of the bumper. It's 80dB with the old oil and 78dB with the new oil. Ta dah!

Isn't science great?

PS. A difference of 2dB is small and would be easily missed. In fact, a difference of 1dB is barely perceptible to a human ear.

Yet, a difference of 3dB is twice the audio power. Yes, a factor of 2x.

Glad that worked out for you. I decided to (at least for now) just stick with my current chamber sealer and the current set up (using ear protection while operating).

Out of courtesy to neighbors a few doors away, I still won't run the sealer around bedtime hours. Other than that, I'll be happy to run the machine loud and proud .

 

[ls99]

The annoyance factor also depends on the OP ear's frequency respose. Not everyone hears tha same frequencies with similar intensity. Ex military or police often have a notch around 600 hz, ears being close to small arms firing.



There are cheap/free audio spectrum analyzer apps available for cellphone/media players. Try to get one and check the frequency responses of the two devices. Bet one has some frequencies with much higher intensity in the annoyance range. Also OP will discover what frequencies are annoying.



I have an analyzer app on my old Ipod touch, it is fun to be in a public place and watch the noise spectrum. In cafe's when refrigerators or coffee griders run, the evidence for the annoyance is visible