60 decibels is the sound level equivalent to a normal conversation. It falls between no sound and pain threshold on the decibel scale. 60 dB is considered safe for human hearing
Human hearing ranges from 20 to 20,000 Hz. Most sensitive between 2,000 and 5,000 Hz. Hearing loss begins around age eight. Women lose hearing less frequently than men
Tinnitus is hearing a noise that others cannot hear. Subjective tinnitus is internal, objective tinnitus is external. Sound can be ringing, blowing, clicking, hissing, or whistling
Earwax protects outer ear canal from dirt and bacteria. Wet earwax has higher lipid content, dry earwax has lower content. Healthy earwax decreases risk of ear infections
Cochlea is a fluid-filled, spiral-shaped structure in inner ear. Approximately 10mm wide, 35mm long when uncoiled. Contains three chambers: scala vestibuli, scala media, and scala tympani. Located behind eardrum, deep within middle ear
Pulsatile tinnitus causes hearing whooshing, thumping, or throbbing in ears. Three types exist: arterial, arteriovenous, and venous. Sounds originate from blood flow changes near ears