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# 1000 dB - how loud is that?

Monday December 26, 2005
1000 dB. That must be pretty loud. Your stereo turned up full? A PA stack? A jet plane? You'll be surprised just how powerful 1000 dB is...

Recently I was describing to a class full of eager sound students the EQ facilities you would normally find on a mixing console. I explained how each band has a frequency control, and a gain control with which the amount of cut or boost is set.

"What is the maximum amount of boost you would expect on the mid frequency band?" I asked, hoping that some students had been reading ahead.

There was a period of silence, then one student called out, "1000 decibels".

1000 dB!

This is rather more than the 10 or 15 dB normally provided, but it got me wondering exactly how loud 1000 dB would be.

The easiest way to work this out is in terms of watts. 0 dBm, which is the standard comparison for an electrical signal in terms of watts equates to 1 milliwatt, or 0.001 W. The watt is the unit of power; power is the rate of production or transfer of energy and can be applied to any form of energy including electricity.

So we will take 1 milliwatt as our 0 dB reference.

The laser in a CD writer has about 100 mW of power, so compared to our reference it is 20 dB

A light bulb could typically be rated at 100 W, so this is 50 dB.

A Formula 1 racing car revving at its maximum develops a whopping 670 kilowatts of power (much more than the car you drive). This, compared to our reference, is approximately 88 dB.

A locomotive, pulling a train of several coaches loaded with hundreds of passengers, may be called upon to develop 5000 kW of power, or 5 Megawatts. In decibels compared to our reference, this is 97 dB. It might not seem like much more than the race car, but with decibels a small increment in numbers leads to a large boost in power.

The Hoover Dam on the Colorado River is rated at just over 2,000 Megawatts. This is equivalent to 123 dB.

We seem to be running out of man made sources of power (other than explosions that are over and done with in a fraction of a second and therefore don't count) and we are still nowhere near the 1000 decibel mark.

But there is one more man made power source - the warp core generator of the Starship Enterprise developing a breathtaking 10,000,000,000,000,000,000 or 1019 watts. This equates to 220 dB.

Looking towards massive power generators in the natural world, the sun produces about 1026 watts of power. This is 290 dB.

The Milky Way, our galaxy, produces 1036 watts. This is 390 dB.

OK, we are going to have to think big here. What about the power output of the entire observable universe, which is 1047 watts?

Still we are only at 500 dB.

So what is as loud as 1000 dB then? Well that can only be the voice of God!