Random punter question of the night

K

Kim Watson

Freshman
Jan 11, 2011
49
0
6
South Shields, United Kingdom
www.polarisaudio.co.uk
Here is a weird one for you.....

Metal gig, 4 band bill........ its LOUD....... Guy comes over to FOH and asks...."whats the safe dB limit for a pregnant woman at a gig?"

How the hell do you answer that??? lol I answered honestly I have no idea....... he then went off to Google it. lol His wife looked very pregnant and also very embarrassed that he had asked.

Good gig though.

Kim x
 
Re: Random punter question of the night

Kim Watson said:
Here is a weird one for you.....

Metal gig, 4 band bill........ its LOUD....... Guy comes over to FOH and asks...."whats the safe dB limit for a pregnant woman at a gig?"

How the hell do you answer that??? lol I answered honestly I have no idea....... he then went off to Google it. lol His wife looked very pregnant and also very embarrassed that he had asked.

Good gig though.

Kim x
Click to expand...

First of all: +1 to what JR said.

I suspect the mother's body encasing the child's would be similar to sticking your fingers in your ears, but I wouldn't know for sure.
 
Re: Random punter question of the night

I don't claim to be an expert, but as my wife is currently 34 weeks pregnant with #2, I'll at least render a guess with some observations.

High frequencies would be attenuated most - I would guess there wouldn't be much above 1K that would make it through (ultrasound machines use "ultrasound" obviously, but the signal is around 150dB - a little different from the average PA signal), and low frequencies would be hardly attenuated at all. Our kid has jumped when I talk in the vicinity of him/her in a medium voice, so clearly the kid can hear that. Our church service's music runs usually in the mid '90's C-weighted and my wife has never noticed the kid being unusually active at that time.

When babies are newly in "outside mode", it is customary for parents to not have them in the service during music for hearing protection reasons.

Since I don't particularly enjoy spending time in places where the sustained levels are above 100dB, I don't take my family there either - pregnant or otherwise, which would be my personal answer to the question.
 
Re: Random punter question of the night

Bennett Prescott said:
Maybe for you! ;)
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Exactly.

Typically loudspeaker are measured at 1M. How far away is the "probe". MUCH much closer than 1M. If you were to measure the output of most HF drivers or woofers at the same distance as the Ultrasound probe-you would find them a LOT louder than you think. A 120dB loudspeaker (at 1meter) would be over 150dB 1 inch away. But wait-the probe is a lot closer than 1 inch-so at 1/4" you are over 160dB. and so forth.

It is NOT the simple single number that you have to "understand"-but rather how it is used and in what context.

A number alone does not mean that much-without the parameters to go with it.
 
Re: Random punter question of the night

Ivan Beaver said:
Exactly.

Typically loudspeaker are measured at 1M. How far away is the "probe". MUCH much closer than 1M. If you were to measure the output of most HF drivers or woofers at the same distance as the Ultrasound probe-you would find them a LOT louder than you think. A 120dB loudspeaker (at 1meter) would be over 150dB 1 inch away. But wait-the probe is a lot closer than 1 inch-so at 1/4" you are over 160dB. and so forth.

It is NOT the simple single number that you have to "understand"-but rather how it is used and in what context.

A number alone does not mean that much-without the parameters to go with it.
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Great post Ivan.

Generally speaking, the noise in the womb is going to be very muted, as the transitions from different mediums is going to have impedance changes, and mute the signal.
The amniotic fluid is going to provide much more protection than just fingers in the ears. The x factor is going to be the sub frequencies. I am not of the opinion that since the sub frequencies are diminished on the Fletcher Munson curves that they are not to be worried about.

Also the OP states "pregnant woman", but it seems agreed that the concern is with the unborn child. (I am of the opinion that pregnant women should be active, interactive, and robustly involved in life, unless it is a bed rest situation.)

But my biggest concern is of once the baby is born. From what I have learned it is very hard on young children's hearing to be exposed to loud sounds before their ears, and muscles that protect the ears are formed. I don't see too many babies/toddlers at concerts, but I get pissed when I see babies at sporting events just so they can be flaunted on the jumbo trons. The crowd noise levels at these events can go well beyond what is safe for those young ears. Get a baby sitter, and leave them in the relative quietness of the home, where they belong.

REgards, Jack
 
Re: Random punter question of the night

Ivan Beaver said:
Exactly.

Typically loudspeaker are measured at 1M. How far away is the "probe". MUCH much closer than 1M. If you were to measure the output of most HF drivers or woofers at the same distance as the Ultrasound probe-you would find them a LOT louder than you think. A 120dB loudspeaker (at 1meter) would be over 150dB 1 inch away. But wait-the probe is a lot closer than 1 inch-so at 1/4" you are over 160dB. and so forth.

It is NOT the simple single number that you have to "understand"-but rather how it is used and in what context.

A number alone does not mean that much-without the parameters to go with it.
Click to expand...
I don't disagree with anything you are saying here, but I guess I don't understand the reason for this particular response. If you and Bennett like to listen to compression drivers at 1" from the driver then I stand corrected - I guess I didn't think it likely that people were routinely subjected to 150dB sound levels at venues in any quasi-normal non-Bennett listening positions. :)

Ultrasound transducers run in the sound range that they do not because "that's just what happens", but because that's the pressure level needed to get a sufficient signal though the substantial attenuation of however much tissue is being examined. Presumably as the listening half of the transducer gets more sensitive with technology improvements, the SPL input will be able to be reduced, and since there is still some concern about the health effects of sonography, this will happen.

I agree with Jack - it's very difficult for me to see parents jeopardizing their children's hearing at tractor pulls, monster truck shows, concerts, etc.
 
Re: Random punter question of the night

Maybe the kid will inform his(her) mother when it's enough?

I once had a rigger who had to leave a show due to an inflammation in one of his internal organs. He could work just fine, but the sheer sound pressure of a kick drum during soundcheck forced him to leave because he experienced an immense pain on every kick drum beat. Sent him off to the doctor for a checkup, nothing to worry about, he just had to wait untill load out before he could resume work. I guess ear plugs doesn't work on your internal organs :)
 
Re: Random punter question of the night

I was really talking about sub frequencies, which can get pretty extreme in larger rigs. I don't know how well SPL numbers hold up when you go from a 1M measurement into the extreme near field, but in any case I assume nobody's standing within a meter of my line arrays. Have to be floating.
 
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