the musical hum of induction motors

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Cybrvanr

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Jan 23, 2005
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As i sit and write this, there's all sorts of activity going on around my house. The old GE mobile maid is washing away in the kitchen, right next to it is my Danby filled with a load of sheets. My Whirlpool compact washer is swishing away in the bathrooom closet, and directly above it, is it's dryer mate tumbling away some clothes for tomorrow. It's all music to me!

Interestingly enough, one of the most pleasing appliance sounds to me is not a washer at all, but an air conditioner. I'm not sure what exactly makes the sound of a window unit so pleasing. It could be the fact that the sound usually is connected with summer comfort, or it could be just the hum is naturally pleasing to the human ear. Maybe even the manufacturers of those things test them out to make the most pleasing sound. Just like all the washers and dryers around here running, an air conditioner sound will put me right to sleep.

I remember my grandmother's house had thru-the wall zone-line air conditioner/ heat pumps in 6 of the rooms (very modern HVAC method for 1959). Now, whenever I stay in a motel with similar air conditioners, it reminds me of staying at my grandmother's house as a young child!
 
White noise

I have to have a fan of some sort to sleep! In the summer it's a window a/c (no central air in this old house) In the winter I run a ceramic heater,on "cold setting" (no heat) The rush of the air,and the monotone of the motor puts me in zzzzzzzzzzzzzzzzzz land! I have to be VERY tired in order to sleep without either.

Rick
 
I'm not a person that needs the sound to sleep, but when I was staying with Richie and Gary recently, his guest room has a little device which you can set to make various sounds for a specific period of time. One of them is actually called "white noise", although for fun I selected the ocean waves one, which was appropriate for the venue, and it was actually very pleasant.
 
Yes-I also sleep to the sound of a fan-and like its breeze even in winter.It all started from when I lived in an apartment building-the fan drowned out the noises.At my present house-drowns out my neighbors barking dogs.Also run an air purifier-its fan helps too.
 
Recipe for a sound sleep

Looks like some of us even have to run an appliance when we are sleeping!! Talk about a bunch of addicts!!!! LOL
Well time to go upstairs and start the fan....
Goodnight all!
Rick
 
RickR, a ceramic heater, that's exactly what I do. Mine has a variable speed fan, either thermostat or manual controlled, but the temp sensor wire has a short in it and the fan only runs on full speed now. Be time for a new one soon, I suppose.
 
music

I gotta have the fan and a radio playing for me to sleep. I turn the radio on the oldies station and turn it just loud enough to be able to recognize the song that's being played.
 
Overhere airconditioners are not very common, although the last few years you see them a bit more. The main reason for this is that our climate is much milder I guess. So I'm not used to the sound of a fan at night. I sleep with earplugs in hotelrooms in the US and even then sometimes wake up when the condenser comes on. But most of the time I put the air on max cold and turn it off when I go to sleep.

On the other hand I easily fall asleep with the TV and the lights on. Thank heavens for timers on TV's!!!
 
All of our senses operate on variable thresholds and continually attempt to "normalize" input, i.e. adjust sensitivity upward or downward. The key here is dynamic range and the time it takes for an input to be normalized.

Examples of normalization include the way your eyes become dark-adapted during the night, so that e.g. a midnight trip to the bathroom is accompanied by that painful feeling of the normal bathroom light being "too bright." Also the classic case of being kept awake by a dripping faucet: the difference between the background quiet and the occasional drip, is a larger dynamic range than the fluctuations of the din of city traffic (minus horns and sirens).

For sleep, very often a critical variable is to maintain a fairly low dynamic range. White noise and "sleep sound machines" do this by adding sound which keeps your hearing thresholds from settling so low that minor background noises would pop out and keep you awake. (I've been using white noise for over 20 years, with a "depth-expanded" white noise system I built that runs off a 3-watt wall transformer, details on request.)

The sound of appliances running will achieve the same result. Regular rhythms in the sound pattern can be restful as long as they are not too punctuated with abrupt changes.

Aside from sleep, the relaxing aspect of sound also has to do with whether it's harmonious or disharmonious (relationship between frequencies), and with rhythms that are compatible with natural body rhythms. Manufacturers try to reduce the prevalence of "odd harmonics" in favor of "even harmonics," and muffle abrupt sounds to the extent reasonably possible. Washers, dryers, dishwashers, and air conditioners are typical examples.

The sound of a vacuum is one of those cases that tends to produce relatively strongly divided opinions. Loud machines with poor harmonics may be seen as "powerful," and any acoustical irritation they produce may be taken in stride as evidence of good cleaning. On the other hand, I'm willing to bet that some of the vacs that people here consider classics, have good harmonics and are relatively quiet, while offering the same suction/cleaning specs as louder machines.

In terms of overt noise pollution, some of the worst offenders are machines that combine high dynamic range with rapid change of frequency and a "random" rhythm. Gas powered leaf blowers and chain saws come to mind because in use they are constantly being revved up and allowed to wind down; the changes in pitch and volume are not predictable to the casual bystander, so they are annoying at a greater distance. On the other hand, a lawn mower that puts out an equal decibel level, is typically a more acceptable sound because it is relatively constant.
 
Acoustical design is rarely given much thought in the home, beyond the question of isolating loud noise sources, and providing musical background in living spaces. However I think this is an area that's long overdue for serious consideration, and the use of appliances as part of the natural home soundscape is a very interesting idea.

In fact it might be suggested that a home soundscape system could be developed that includes various types of recorded background soundtracks, so you could choose a different one any time you liked. For example: city (traffic and pedestrian din with occasional subway clatter and distant siren), suburb (outdoor family sounds including lawnmower and occasional passing car), rural (wind in the trees, occasional birds, mostly quiet), farm (animals, tractors, etc.), industrial (factory din with more truck traffic) etc. Then on another setting, choose the weather: calm, wind, rain, thunderstorm in distance, thunderstorm close by, snow (muffles other sounds as does a real snowstorm, occasional snow plow passing).

This rapidly lends itself to interesting variations. For example, unlikely settings such as military bases or even battle zones (sounds of marching, drills, and equipment in background, sounds of rifle range shooting; or sounds of incoming and outgoing artillery, etc.); construction sites (choose type of construction, e.g. home building, highway, skyscraper; phase of construction, i.e. excavating equipment, carpenters hammering on frame, etc.); airports nearby (large or small, different types of planes coming & going); "outer space" (perhaps a soundtrack from a space station). Ethnic themes might be added by changing the sound of background conversation noise to match various languages; also background music from relevant countries or cultures.

All of this would be fairly easy to accommodate on large-capacity hard drives. For example we presently have voicemail systems that will store hundreds of hours of messages and have dozens of "ports" for simultaneous access; this could be adapted to store sound snippets and provide channels into an audio mix. And then of course, a master volume control to set a comfortable overall level, and a tone control whose primary subjective effect would be to change the sense of "presence" vs. "distance" from the "sound source."

You could set up themes and programs and store them, adjust the mix, adjust various occasional or random sounds (e.g. add an "ice cream truck" to the suburb soundtrack a few times a week), and use the same theme or a different theme every day.

Another variation might be even simpler to implement: web-based microphones placed in public locations in various settings, so people could tune it in like "web radio" that was constantly running, and get the sounds from those areas. The desktop software would have to be designed to store a large enough sample to cover occasional gaps and glitches in transmission. And yet you could, with the click of a mouse, "be" in New York or Wyoming or Kansas, in London or Iraq or even on the space station, or in a suburb, on a farm, or anywhere else you chose.

Hmm. Home Soundscape System. I wonder if I could get someone interested in producing this...?
 
Maybe also the sound of multiple computers running together. I have a friend who's a computer nut that says he will wake up in an instant when the 4 computers running in his office suddenly go quiet during a power outage. He also says he likes the dull roar that comes from all the computers in an office server room.

I too, find that lawnmowers put out a pleasing tone too. Even more approperiate would be an example of a go-kart. One of the neighbors kids have one he drives through the woods on a nice Saturday. It has a lawnmower engine on it, but because he's speeding up and slowing down as he goes through the turns, it's not as pleasing. Outside of the changing in speed, chainsaws, leaf-blowers and weed eaters have two-cycle engines which produce more odd-order harmonics. Leaf blowers especially, since they combine the odd-order harmonics of a high speed centrifugal fan (like a household vacuum) with a high-revving two cycle engine. I have sort of found the sound of a leaf blower indicitive of autumn. The sound of one makes me think of cooler, shorter days, back to school, halloween, and stuff like that.
 
I used to have a rechargeable cordless electric lawnmower-Loved that machine-was queiter than an upright vacuum and made mowing the yard as easy as vacuuming the living room floor.Unfortunately the plastic deck wore out from the sand and pine straw-those are ABRASIVE.If it had a steel deck-bet it would still be going-was handy to use for trimming after the Snapper rider.Those 2 cycle lawn care appliances drive me NUTS-their motors are TOO LOUD and their buzzing tone is annoying.The leafblower esp.At times think they are a useless device-prefer a broom or rake.Or if I do want to blow leaves-configure one of my Kirbys as a blower and use the wand attachment on the hose to blow with-works better than the gas one and queiter too-only bugaboo is the cord.I could see the chainsaw though-it would be very difficult to cut down trees with hand saws are axes.I do have an electric chain saw and that is handy for some of those smaller trees-same with a cordless Sawzall-its even more fun to use.
 
Cybrvanr: Compuers, yes, up to a point. Today I was working on a phone system in a server room that must have been 85 dB of not-quite-white noise, which was driving me crazy because it was too loud. Your friend waking up: that's due to an abrupt change in the stimulus: abrupt silence is almost as jarring as abrupt loud.

Tolivac: Electric mowers, yes; and also electric snow throwers, which are still made in reasonable capacities. As for gas powered blowers, I'd just straight-up make the damn things illegal. Using a vac on the blower setting is clever. I used to do something like that for cleaning the garage when I was a kid.

The vacuum machines the city used to pick up leaf piles, had a low hum that was not objectionable. We used to have a lawn sweeper, push it and it picks up the leaves. Even before the sweeper, raking was a fun exercise, and always went along with fresh warm chocolate chip cookies and a tall cold glass of milk.

In California, leaves fall lightly all year and are easily swept to the curb, where the regular street sweeper picks them up on its monthly rounds.
 
Today:I would think with the advent of cordless power tool technology-If tool makers can build cordless drills and circular saws-I would think a cordless blower,weedeater,would not be a problem.I would think a cordless circular saw motor would need to be higher horsepower than the leaf blower motor would need to be-would think the cordless tool technology could make the fractional horsepower 2 cycle engine obselete.-and quiet lawn care appliances.No more noise or air pollution(from burning the fuel-oil mix in the 2 cycle motors)One lawn care contractor I had cut down some storm damaged trees in my yard-he used a Stihl backpack blower that was very quiet-he even was using it to clean my house roof while I was asleep!didn't waken me.The design of that machine was very good-both the motor(2 cycle gas) and the blower was well designed to be quiet.The throttle was on its wand handle-pretty nice.Those street sweeper machines use larger gas or deisel 4 and 6 cylinder"industrial engines" built by Ford,chrysler,or even John Deere.They turn large slow turning fans that don't generate a lot of noise becuase they are very large and turn slowly.Any vacuum cleaner that can be configured as a blower could be made to blow leaves-the TriStar can be configured to do that.You just may need to use and extension cord along with the vacs cord-just be sure to use a large guage extension cable-14ga wire or larger.When I used to man a commercial transmitter plant years ago-2 FM transmitters and one AM transmitter-their blower noise would make a drone that would make you drowsy-than the sound of a silence senser(program loss) or an overload relay tripping-that would wake you up again!
 
range and power

I think the big problem with making a fractional-horsepower blower, weedeater, or the like is not necessarily giving a lot of power, but providing power over the continuous time frame the device is in use. A cordless drill can provide some enormous power, but you are only operating it for a few seconds at a time. A leaf blower is typically asked to run for an hour or more to clean up a yard, even though it does not need an enormous amount of horsepower.

Now, there have been some rechargeable electric lawn mowers on the market recently that work quite well. These have a 3 HP electric motor, powered by two deep-cycle batteries about the size of automobile batteries. The mowers are HEAVY with those batteries in them, but they do just as good of a job as the gas power mowers. I imagine a leaf blower with enough batteries to get the job done would be quite heavy!

Now, one of the things that interests me very much so is electric automobiles. I've always found it odd that the electric car has not caught on. Yes, you are facing the same range issue that a leaf-blower or weed eater would, but the trick behind an electric car is that it is "re-filled" every night. The Saturn Impact had a range of 125 miles. I don't know of too many people that would exhaust this range in a single round trip to work. (The 6 gallon fuel tank gave my old Honda Civic range that was not much better than that!) With battery technology becoming so good lately, combined with motor control technology, electric cars are really feasable. Especially if you consider the fact that you don't need to worry about tuneups, oil changes, radiator coolant, air filters and all the other periodic service a gasoline car needs. Maybe that's the reason the car companies don't want them to catch on...they're too reliable to give return business with "service after the sale" needs.

Now, a more feasable fun thing to do with electric propulsion is drag racing! Yep, that's right, you don't need your earplugs for this motorsport! Drag racing electric cars is a pretty neat concept because enormously powerful cars can be put down the track since they are only running for a 1/4 mile at a time. Range is not that much of an issue. Some of the electric dragsters have times that will put a gasoline powered vehicle up for a good run!

National Electric Drag Racing Association

The National Electric Drag Racing Association (NEDRA) exists to increase public awareness of electric vehicle (EV) performance and to encourage through competition, advances in electric vehicle technology.
www.nedra.com
 
Yes,I used to own and use the rechargeable electric lawnmower.during the 70's and early 80's GE used to make an electric lawn tractor-the "Lectric-Trac"Occasionally tractor collectors run into them today.There was a lawnmower dealer in forestville,MD that used to sell them.they were in a small storefront-so if you wanted one-they ordered it for you.it could be obtained with a lawn mower deck,snowblower and a rototiller and dozer blade.In the demo video showed at the store they showed the GE tractor connected drawbar-drawbar with a 12 gas tractor. the GE tractor was rated for 10hp.that GE one was dragging the gas one all over the feild where they demoing it!. Was impressive.The gas tractor driver was trying to shift gears,etc and the GE tractor just hummed along dragging its opponent.And the machine was SO quiet--just the gentle whirring sound of the mowers blades and the slight hum of the tractor motor.the machine was heavy from all of its lead-acid batteries. Can't remember the runs times.Would love to have one!!Oh yes one mower builder makes a rechargeable push mower with a removable battery pack.You could have more than one battery-one is charging and the other is being used.I would think the Variable Frequency AC drives that have revolutionized the electric traction in the RR industry could be applied to cars!!Both GE and GM electro Motive division now build AC traction locomotives.Instead of a DC motor these loco's now use AC motors coupled to the solid state VFD drive controllers.What you mentioned about electric cars reduced maintenance over fossil fuel models is the big reason oil companies and car companies don't want to switch.the technology has been with us for years.That electric drag racing site certainly could inspire more interest in electric vehicles-introducing them in the sporting way is good.and this could inspire folks to come up with new designs! Wouldn't it be interesting to make up an electric drag vehicle that uses an overhead wire(like an electric locomotive) or run from a third rail like a subway train-that would be something to see and --not hear-just the whine of the electric motors and gentle hum of the transformer and VFD drive.when I used to ride the Wash DC Metro subway system-their subway cars use VFD traction-you can hear the VFD change frequency as the train passes-either accerating or slowing down you can hear the sound of its VFD drive.And you had better not put any magnetic media such as tapes,or computers over the traction motor drives-they generate a VERY strong varying magnetic feild-I saw a few paper clips on the floor over one almost stand on end as the train was speeding up or slowing down!!.
 

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