BC-HIS key terms

A logarithmic unit used to express the ratio between two sound intensities or pressures. Because the range of human hearing is enormous, sound levels are compressed into a manageable scale where equal steps represent equal multiplicative ratios.

A decibel measure referenced to a standard physical pressure of 20 micropascals, the approximate threshold of normal hearing. It describes the absolute physical intensity of a sound regardless of how a listener perceives it.

A decibel scale referenced to average normal hearing thresholds for a given transducer, so 0 dB HL represents the softest sound a typical listener detects. It is the scale used to plot audiograms.

The number of cycles of a sound wave completed per second, measured in hertz. It corresponds to the pitch of a sound, with human hearing spanning roughly 20 to 20,000 hertz.

The physical distance between successive corresponding points on a sound wave, such as from one compression to the next. It is inversely related to frequency and affects how sound interacts with rooms and objects.

A sound consisting of a single frequency with no overtones, represented graphically as a simple sine wave. Pure tones are the standard stimuli for measuring hearing thresholds because they are precisely controllable.

The tendency of a system to vibrate with greatest amplitude at particular frequencies when driven by energy at those frequencies. In hearing aids and ear canals, resonance shapes which pitches are naturally amplified.

The bending and spreading of sound waves as they pass around obstacles or through openings. It allows lower-frequency sounds to reach a listener even when a barrier blocks the direct path.

The difference in level between a desired signal, such as speech, and competing background noise. A larger ratio means the signal stands out more clearly and is easier to understand.

The visible outer ear made of cartilage and skin. Its folds and curves collect sound and help the listener locate where a sound is coming from, especially in the vertical plane.

The tube leading from the outer ear opening to the eardrum. It channels sound inward, protects deeper structures, and its length and shape create natural resonance that boosts mid-range frequencies.

The eardrum, a thin membrane separating the outer and middle ear. It vibrates when struck by sound waves and transfers that motion to the ossicles.

Three tiny bones of the middle ear, the malleus, incus, and stapes, that transmit vibrations from the eardrum to the inner ear. They also amplify force to match the inner ear's fluid environment.

A passage connecting the middle ear to the back of the throat that equalizes air pressure on both sides of the eardrum. It normally opens briefly during swallowing or yawning.

The snail-shaped, fluid-filled structure of the inner ear containing the sensory organ of hearing. It converts mechanical vibration into electrical signals sent along the auditory nerve.

The sensory structure within the cochlea that rests on the basilar membrane and contains hair cells. Movement of the membrane bends the hairs, triggering nerve impulses that encode sound.

Sensory receptor cells in the cochlea that convert mechanical motion into electrical signals. Outer hair cells sharpen and amplify responses, while inner hair cells send the main neural output.

Age-related hearing loss, typically affecting high frequencies first and gradually worsening over time. It usually results from cumulative changes to inner ear structures and is most often sensorineural.

Hearing loss caused by a problem in the outer or middle ear that blocks or reduces sound reaching the inner ear. It generally reduces overall loudness and can often be treated medically or surgically.

Hearing loss resulting from damage to the inner ear or auditory nerve. It typically reduces clarity as well as loudness and is usually permanent, so amplification is a common management approach.

A graph showing a person's hearing thresholds across frequencies, with frequency on the horizontal axis and hearing level on the vertical axis. Symbols mark each ear and the type of testing used.

The difference between hearing thresholds obtained with earphones or inserts and those obtained with bone-conduction testing. A meaningful gap suggests a conductive component to the hearing loss.

A measure of how well a person understands speech, often scored as a percentage of correctly repeated words. Results help predict benefit from amplification and guide realistic expectations.

The ability to understand speech when competing background sound is present. It is often the most important real-world listening challenge for people with hearing loss and a target for hearing aid features.

The reduction in high-frequency sound reaching the ear farther from a source because the head blocks it. This creates a level difference between ears that helps listeners locate sounds and separate them from noise.

The boosted loudness of low-frequency sounds, including the wearer's own voice, when the ear canal is blocked. It is a common complaint with custom or tightly fitting hearing aids.

The component of a hearing aid that converts amplified electrical signals back into sound. Its placement and type influence output, frequency response, and how the device fits in the ear.

The hearing aid component that picks up acoustic sound and converts it into an electrical signal for processing. Its directionality and placement strongly affect performance in noise.

The amount by which a hearing aid increases the level of an incoming sound, expressed in decibels. Prescribed gain varies with frequency and input level to match a wearer's hearing loss.

The maximum sound level a hearing aid can produce, often limited to protect the wearer from uncomfortable loudness. It is set to keep amplified sound within a comfortable range.

A signal-processing strategy that reduces gain for louder inputs and increases it for softer ones, squeezing a wide range of sounds into a narrower usable range. It helps keep speech audible without becoming uncomfortable.

A microphone system that is more sensitive to sounds arriving from the front than from behind or the sides. It improves the signal-to-noise ratio when the wearer faces the person speaking.

A small channel through an earmold or hearing aid shell that lets air and low-frequency sound escape the ear canal. It reduces occlusion and can be sized to tune the fitting.

An unwanted whistling or squealing caused when amplified sound leaks back into the hearing aid microphone and is re-amplified. It is managed through good fit, venting choices, and feedback suppression features.

A verification procedure using a probe microphone placed in the ear canal to measure the actual sound delivered by a hearing aid. It confirms that prescribed targets are met on the wearer's real ear.

The reduction in sound level reaching the eardrum that occurs when a device or headphone is placed at the ear. It is greatest at high frequencies and is accounted for during testing and fitting.

A process of clearly explaining assessment and treatment options, risks, benefits, and alternatives so a client can make a voluntary decision. It respects client autonomy and is a core professional obligation.

The set of activities a professional is legally and ethically permitted to perform based on training, licensure, and regulation. Working outside it can harm clients and carries legal consequences.

The ethical and legal duty to protect a client's private health information from unauthorized disclosure. It may only be broken with permission or when required by law.