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Discussion » Statements » Rosie's Corner » I know these are not the same thing. A toaster is silent while it toasts. A microwave is noisy while microwaving. WHY?
RosieG

I know these are not the same thing. A toaster is silent while it toasts. A microwave is noisy while microwaving. WHY?

Why can't motors be silent? Gas or electric or whatever.

Engines on a jet. NOISY.

Leaf Blowers are NOISY

Is noise non-eliminatable?

Why do dentist's drills make so much noise?

Why can't jackhammers break concrete with breaking your eardrums?

Why do you hear streetsweepers and trash trucks?

SILENCE.  A goal or a fantasy?

Posted - August 23, 2020
Tags : None

Responses


  • 44690
    Noise/sound is the mechanical vibration of air molecules at frequencies inside hearing range. Engines, motors, blowers etc all do that. Toasters don't. We cannot silence them by their very nature.
      August 23, 2020 7:43 AM MDT
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  • 113301
    Oh. How we are physically made makes it impossible unless of course one is hard of hearing. So noiseless is impossible then? Oh wait a minit. They put SILENCERS on guns E. Could they do that? They put Mufflers on cars but you still hear them. How is a silencer on a gun different from a muffler on a car and could you muffle a blower to achieve silence?? Thank you for your reply! :)
      August 23, 2020 7:50 AM MDT
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  • 44690
    Gun silencers reduce the speed of the bullet below the speed of sound. Un-suppressed bullets are much faster, thus you hear the shock wave they, and the gunpowder make.
      August 23, 2020 8:39 AM MDT
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  • 113301
    I had no idea that a silencer had any affect at all on the bullet speed. Of course I have no clue about anything related to guns. You know what I'm going to ask why are silencers legal? I assume they are right? Thank you for your reply E! :)
      August 23, 2020 8:42 AM MDT
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  • 16895
    If you could see infrared, toasters would be blinding.

    Kettles hiss before they whistle.
      August 23, 2020 7:47 AM MDT
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  • 113301
    So you're saying it's the PHYSICAL PROPERTIES of the thing itself that is the cause? OK R so how about this? A gun can have a silencer placed on it. Why can't a blower have a silencer or jet engines have silencers? I know I'm missing some important point. So I'm waiting to be clued in. We can't change the physical properties of things but we could change how we perceive them right?
      August 23, 2020 7:52 AM MDT
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  • 16895
    Weight and practicality. A silencer makes a gun significantly heavier, a practical silencer for a turbofan engine would make an aircraft too heavy to fly, one for a leafblower would make it both cumbersome and expensive. Most of the racket from a jackhammer is caused by impact with the concrete, a quiet one wouldn't break it.
      August 23, 2020 8:03 AM MDT
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  • 113301
    Thank you for the "extended" info R. I appreciate it. Oh I just asked a question about Sir Howard Florey and the next question I'm going to ask is how many lives have vaccines and antibiotics saved? I know. Impossible isn't it? I'm going to ask anyway!  I just told Jim about Sir Howard Florey. He had no clue. I wonder why Fleming seems attached to it more than the other two? Any clue?
      August 23, 2020 8:12 AM MDT
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  • 13277
    Have you driven a car with an electric or hybrid engine? Those are very quiet compared to traditional gasoline models.
      August 23, 2020 8:46 AM MDT
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  • 3719
    It's moving parts, the air they move by acting as fans, and vibrations radiated from metal panels, that create the noise.

    A toaster is a static heater. A microwave oven has motors driving its turntable and the cooling-fan for its electronics (which themselves are silent).

    A jet engine is as loud as it is from a combination of the jet itself (a huge volume of fast moving gas) and the siren effect of the engine's internal turbines. Aircraft-engine designers have had to go to considerable effort and cost to make engines a lot quieter than they used to be for equivalent power.

    A leaf-blower consists of a powerful fan driving a lot of air through a nozzle, but worse if driven by a petrol engine rather than electric motor.  

    The sound of a dentist's drill is from it acting as a siren, with its air-motor rotating at many-1000 rpm. What you hear, or feel, in your head when it is actually drilling a tooth, is the burr's several cutting-edges cutting the tooth enamel at very high speed. 

    A jackhammer (called a pneumatic drill or road-breaker in the UK) is noisy because it contains a rapidly-reciprocating piston hammering the head of the "steel" (chisel) inside the tool. They can be fitted with absorbent jackets that reduce the noise considerably, but are still loud. The drilling itself, in the concrete, makes very little noise because the steel stays in contact with it, and that sound is masked by the machine's own sound.

    Street-sweepers and trash-trucks are diesel-engine lorries anyway, but the special equipment they carry creates its own sounds. Most of the sweeper's noise is from the rotary brushes on the road, and the air travelling through the vacuum system.

    The quietest prime-mover for power-output, is actually the conventional steam-engine, if the exhaust steam is not released into the air in a series of heavy pulses as on a railway locomotive when working hard!


    Your would be hard-pressed to find anywhere that is absolutely silent, at least in human terms. The quietest places I know are in dry caves, but silence to that extent even in Nature, above ground, is extremely rare.          
      August 24, 2020 4:34 PM MDT
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