Google says:

http://www.childrenshearing.org/custom/hearing_health.html

Towards the bottom is mentions about infants, although he states that infants hear things 20 db louder than adults, there isn't any reference to a study that confirms it.  Makes sense, but I'd still be a bit skeptical.  It still however says that 'toys' shouldn't be louder than 85 db, which is still pretty loud.  Any damage however would have to be a result of prolonged exposure (or acute really freakin' loud noises), not a 10min session on a machine.  Most other sites say that signs of damage occurring would be pain/ringing, so as long as the baby isn't complaining, it's probably not hurting.

I'm all for exposing kids to noise, when our kids were born, they didn't even have a bedroom door.  Their hearing is fine and now they sleep through anything.

No way, if their hearing was that sensitive they'd deafen themselves with their screaming / shrieking.  

That being said, do what your wife says.  She's seriously chemically and emotionally imbalanced right now.

Daniel

Quoted from cooke

When my daughter was an infant, I'd wear her in the baby sling while playing pinball to get her to go to sleep.

I did the same with my first.  Now, at eight years old, he can beat me half the time on any of my games.

Quoted from McMean

No way, if their hearing was that sensitive they'd deafen themselves with their screaming / shrieking.  

That being said, do what your wife says.  She's seriously chemically and emotionally imbalanced right now.

Daniel

I'm with you on this one. However wrong I think she is on this one...it's way easier to let her have her way on this one.   On another note...I downloaded a decibel monitor on my iPhone to measure the pinball machine on...highest it got to was around 80db...

Ave. Conversation was around 50db
Shouting at the top of the stairs, with the baby in her arms, for me to do something, would be double any pinball machine...but who's counting. Lol