lub
S1 makes a "lub" sound. It is the first heart sound in a normal rhythm. The sound is produced when the AV valves close.
The AV valves lie between the atria and the ventricles of the heart. The closing of these valves produces the lub-dub sound heard when the heart is auscultated.
The loudest sound that we can hear is about 130 decibels.
In my opinion it is the drums that have the loudest raw sound, but if you connect your guitar to an amplifier then the sound will have increased.
The 1st heart sound, S1 (lub), marks the beginning of systole (end of systole). Related to the closure of the mitral and tricuspid valves. Loudest at the apex.
The loudest sound ever recorded are rock concert speakers.
At a very close distance to the spider you hear the loudest sound.
I believe the Saturn V moon rocket was the loudest man made sound.
The loudest noise or sound is The Bloop because in 1997, U.S. NOAA heard a sound that is never been heard of that is also the loudest sound ever. The sound can cause from more than 5,000 km away from it's source. If it is an animal, it is louder and bigger than the loudest animal and the biggest animal in Earth.
194 dB (decibels) is the loudest sound on Earth ever. Some people say that the eruption of Krakatoa in 1883 was the loudest sound ever, being heard at 5,000 kilometers away! That eruption was around 180 dB!
The Destruction of a a star.
There is no upper limit.