These middle ear bones are attached to a tiny membrane covering the entrance to the cochlea. When the bones vibrate, the membrane moves with them, causing thousands of microscopic hairs (outer hair cells) in the cochlea to vibrate and bend over. These hairs are connected to specialized hearing cells which change the vibrations into electrical currents. These electrical currents are carried along the hearing nerve to the brain and the brain interprets them as sound.

Because hearing loss is an invisible condition, the effects are often mistaken for other problems. The person may appear inattentive, unfriendly, detached, rude, not very bright, confused, or even senile. The following is a list of symptoms which are often associated with hearing loss but may masquerade as other types of behaviors. When these symptoms are noticed, an appointment with an audiologist should be made immediately for a complete hearing evaluation.

• Has "selective hearing" or "hears what he/she wants to hear."
• Hears some people's voices better than others.
• Cannot hear some sounds, such as a loud faucet drip, in spite of being able to hear other sounds which seem soft such as a whisper.
• Hears better when the speaker's face can be seen.
• Has trouble hearing clearly on the telephone and may avoid talking on the telephone.
• Turns TV or radio too loud.
• Says "What?" or "Huh?" frequently.
• Does not always respond to his or her name.
• Has trouble locating the source or direction of sounds.
• Complains that others are mumbling.
• Has great difficulty hearing clearly when competing sounds are present and may prefer to avoid these situations, such as noisy groups.
• Speech development is delayed or speech is difficult to understand especially in children.
• Talks too loud or too soft.
• Complains of ringing or buzzing in the ears.
• Misunderstands directions or procedures.
• Startles when someone enters the room.