Engineering News

Two 140 db horns - blimey, that's 280 db!

Even at 146dB that is over even the highest pain threshold estimate.

Lousy way to start the day

What? I couldn't hear you... the ringing in my ears wont stop.

Yes, 140 dB + 140 dB =146 dB.

please check his post, man. he was talking about threshhold of pain, and not trying to do arithmetic.

Who made you the post police? dB is the scale of measurement of sound which is the object of the post and it is not about "arithmetic" it is about how to add numbers on a logarithmic scale that is used to measure what the pain threshold is on a numeric scale. But perhaps you were unaware of how all that works. I forgive you.

140dB x2 =143dB. A doubling of power is an increase of 3dB whereas a doubling of sound pressure level is +6dB. Self evidently 2 x 140dB sources represent a doubling of power.

Strictly 140dB is meaningless as it is only a ratio. Absolute units need to be specified e.g. dBA spl or dBLeq.

Whatever the units this is loud enough to cause hearing damage even with short term exposure. This product won't have a long life after the company has to pay damages to its customers.

It's not a commercial product - some geezer just bought a couple of car horns & lashed them up to his alarm clock using a relay & a lump-in-the-cord PSU he had lying around.

Thanks, you are correct, an oversight on both our parts.

When referring to sound it is commonly assumed that the reference 0 dB sound pressure is 20 uPa.

The ANSII exposure limits state that the daily limit for exposure between 130 and 140 dB (RE 20 uPa) is less than one second. I believe above 140 it is expected that significant hearing damage is instantaneous and so there is no need to specify exposure limits.