Chara (alga) Chara is a genus of charophyte green algae in the family Characeae. They are multicellular and superficially resemble land plants because of stem-like and leaf-like structures. They are found in fresh water, particularly in limestone areas throughout the northern temperate zone, where they grow submerged, attached to the muddy bottom.
The eustachian tube (also known as the auditory tube or the pharyngotympanic tube) joins the tympanic cavity with the nasal cavity (nasopharynx), allowing pressure to equalize between the middle ear and throat.
dB of sound pressure level (dB SPL) is defined as: 20 log 10 p1/p0 where p1 is actually measured sound pressure level of a given sound, and p0 is a reference value of 20Î¼Pa, which corresponds to the lowest hearing threshold of the young, healthy ear.