Hearing & Distinguishing Specific Heartbeats

[JCurwen3]

How might one build a character with hearing sensitive enough to hear heartbeats (or similarly faint noises) in "Normal Traffic" at a range of 128 yards at no penalty to the Hearing roll?

Hearing "Normal Traffic" at that range would be at -3, so that's just Acute Hearing 3 to do that at no penalty. And I know distinguishing specific heartbeats would require Discriminatory Hearing.

I'm just not sure how to account for the effect of the background noise of "Normal Traffic" on hearing a much lighter noise. Do I go by steps on the scale? So, to hear "Leaves rustling" in "Normal Traffic" at 1/4 yard, it's -6 (6 steps away for noise), and to hear that at 128 yards it's -6 for background noise and -9 (9 steps for range) for a total -15? It's not clear from the text (about the background noise impact).

And a heartbeat is much quieter than "Leaves rustling". A normal human can't hear a heartbeat except at pretty much 0 range (putting ear against the chest or other place with a strong pulse). I imagine the penalty to hear a heartbeat even at 1/4 yard in perfect quiet might be quite staggering.

Any suggestions?

[malloyd]

Originally Posted by JCurwen3

How might one build a character with hearing sensitive enough to hear heartbeats (or similarly faint noises) in "Normal Traffic" at a range of 128 yards at no penalty to the Hearing roll?

Detect (Heartbeats) comes with analyzing normally, so you can tell them apart. If you want to simulate hearing, you probably need whatever the No Targeting modifier is called on Detect.

With realistic sound amplification you probably can't do this. Heartbeats at this range are going to be below the intensity of environmental noise - in fact they're probably below the *thermal* noise - the random movements of the molecules in the air. You won't be able to pick them out.

[JCurwen3]

Originally Posted by malloyd

Detect (Heartbeats) comes with analyzing normally, so you can tell them apart. If you want to simulate hearing, you probably need whatever the No Targeting modifier is called on Detect.

I was ideally looking for a hearing based solution (however many points might need to be in Acute Hearing). Most of the time in fiction, people who can do things like hearing heartbeats from a distance have super-hearing and are shown to be able to hear other noises of similar volume.

Originally Posted by malloyd

With realistic sound amplification you probably can't do this. Heartbeats at this range are going to be below the intensity of environmental noise - in fact they're probably below the *thermal* noise - the random movements of the molecules in the air. You won't be able to pick them out.

I think I'm looking for "realistic adjacent" (since this is definitely not something found in reality). ;-)

[johndallman]

As well as whatever you use for the acuteness, you're going to want Protected Sense (Hearing) to avoid being deafened by your own stomach rumbles.

[JCurwen3]

Originally Posted by johndallman

As well as whatever you use for the acuteness, you're going to want Protected Sense (Hearing) to avoid being deafened by your own stomach rumbles.

Wow, yes, very good point, I'd forgotten about that. It could be dangerous just to whisper, let alone yell with that kind of hearing otherwise.

[Fred Brackin]

So ttere I was Googling to find out how loud a human heartveat was and the first etry was this.....

http://forums.sjgames.com/showthread.php?t=70101

If your answer isn't in there all I can add is that 0 decibels is 4 numbers lower than the bottom of the chart in HT.

At 128 yards you'd need (I think) at least 13 levels of Acute Hearing and Discriminatory.

As this is probably more expensive than the Detect(Heartbeats) with Profiling Powers solution I'd let it work.

I caveat the the above is dubious in true scientific accuracy but might be close enough for Gurps.

[Bruno]

Parabolic Hearing will let you filter out ambient noise penalties at a 1:1 ratio, so you will probably want that for Super Heartbeat Detecting Dude. EDIT: I misremembered, it halves effective distance. Still something to consider.

High Tech p158 says the penalty for traffic as your background noise is -5.

[Bruno]

Originally Posted by malloyd

With realistic sound amplification you probably can't do this. Heartbeats at this range are going to be below the intensity of environmental noise - in fact they're probably below the *thermal* noise - the random movements of the molecules in the air. You won't be able to pick them out.

You can totally hear heartbeats at about arms length in a reasonably quiet room. It takes a stethescope, but that's not strictly amplifying anything - it's blocking out all other sounds and getting you the conductive surface with the chest wall.

Which is probably a few levels of Parabolic Hearing with very specific limitations on it.

[malloyd]

Originally Posted by Bruno

You can totally hear heartbeats at about arms length in a reasonably quiet room. It takes a stethescope, but that's not strictly amplifying anything

Actually it is an amplifier, that's why you have a big bell contact feeding a narrow tube - it's a amplifier horn turned backwards, trading area for pressure.

Anyway, the only number I can find for heartbeats is about 10^-15 W sound energy. That'd be about -30 dB at 1 yard. Since one doubling is - 6dB, if I want to raise that to around the 30 dB of conversation, I'll need 10 doublings for that, then another 7 for going to 128 yards, call it Acute Hearing +38 to make it as loud as conversation at 1 yard. Alternately, I guess 17 levels of Parabolic Hearing, provided you were facing exactly the right way.

[NineDaysDead]

Originally Posted by Fred Brackin

So ttere I was Googling to find out how loud a human heartveat was and the first etry was this.....

http://forums.sjgames.com/showthread.php?t=70101

And 2 years before I started that thread, there was Beating Hearts. Maybe someone should ask Kromm as this is at least the 3rd time it's been asked.