Properties of Sound and the Profession of Audiology

Vocabulary flashcards covering basic physical properties of sound waves, acoustic measurements, decibel scales, audiometric testing techniques, and the history and practice of the audiology profession.

Acoustics

The study of the physical properties of sounds in the environment, how sound travels through air, and how it is affected by objects in its path.

Psychoacoustics

The branch of science that studies the psychological and physiological perception of sound by human listeners.

Brownian Motion

The constant, random movement of air molecules at high speeds caused by thermal energy, which generates a steady ambient pressure.

Boyle's Law

The physical law describing an inverse relationship between air volume and air pressure when mass and temperature remain constant.

Compression

A phase in a sound wave where vibrating air molecules are pushed together, causing air pressure in a given volume to increase above ambient level.

Rarefaction

A phase in a sound wave where air molecules overshoot equilibrium positions due to inertia and momentum, resulting in spread-out molecules and reduced pressure.

Hooke's Law

The elastic principle stating that a restoring force is directly proportional to the distance of displacement and acts in the opposite direction.

Transverse Wave

A wave motion in which individual particles move up and down at right angles (perpendicular) to the direction the wave travels.

Longitudinal Wave

A wave motion in which individual particles move parallel to the direction of wave propagation, as seen in sound waves.

Simple Harmonic Motion

Vibratory motion in which a simple sound wave graphs as a sinusoidal wave with compression amplitude equal to rarefaction amplitude.

Frequency

The number of completed cycles of vibration per second, measured in Hertz ($Hz$).

Period ($t$)

The amount of time required for $1$ cycle of vibration to occur, calculated as $t = \frac{1}{F}$.

Wavelength ($\lambda$)

The physical distance traveled by $1$ complete cycle of a sound wave, calculated as \\lambda = \frac{v}{F}\.

Velocity ($v$)

The speed at which sound propagates through a medium, depending on density and elasticity ($331\,m/s$ in air at $0\,^\circ\text{C}$).

Phase

The position of a waveform relative to a reference point in time, expressed in degrees or radians.

Root-Mean-Squared (RMS) Amplitude

An average amplitude calculation obtained by squaring points on a waveform to eliminate negative values, averaging them, and taking the square root.

Pure Tone

A simple periodic wave containing a single frequency that is perceived as a musical tone at a specific pitch.

Aperiodic Wave

A sound wave in which individual cycles vary in duration and lack a specific frequency or pitch, perceived as noise.

Fundamental Frequency ($F_0$)

The lowest frequency component of a complex periodic wave.

Harmonics

Whole-number multiples of the fundamental frequency in a complex periodic sound.

Fourier Analysis

A complex mathematical analysis that decomposes any complex wave into its constituent sine wave frequencies, amplitudes, and phases.

Constructive Interference

The combination of two waves of equal frequency and phase moving in the same direction, resulting in increased amplitude.

Destructive Interference

The interaction of two identical frequency waves that are $180\,^\circ$ out of phase, causing their pressures to cancel each other out.

Resonance

The tendency of a system to vibrate with maximum amplitude when exposed to a frequency close to its natural frequency.

Impedance

The total opposition a medium presents to the transmission of acoustic energy, determined by its mass, elasticity, and friction.

Decibel ($dB$)

A logarithmic, non-linear unit representing a ratio between a measured sound intensity or pressure and a standard reference level.

dB HL (Hearing Level)

The decibel scale used on audiograms where $0\,dB\,HL$ represents audiometric zero, the average threshold for normal human hearing across frequencies.

dB SL (Sensation Level)

The sound level in decibels above an individual patient's specific auditory threshold at a given frequency.

Localization

The process of identifying the spatial direction of a sound source, relying on interaural time and intensity differences horizontally and pinna cues vertically.

Masking

The phenomenon where the presence of one sound raises the detection threshold of another concurrent sound, making it inaudible.

Audiometer

An electroacoustic instrument used to measure hearing sensitivity by delivering controlled pure tones or speech signals through transducers.

Bone Conduction Audiometry

A pure-tone testing method that transmits sound waves directly to the inner ear by vibrating the skull using a bone oscillator.

Sound Level Meter (SLM)

A hand-held device used to measure sound pressure levels in the environment for industrial noise assessment and equipment calibration.

Audiology

The primary healthcare profession concerned with the evaluation, diagnosis, management, and prevention of auditory and vestibular disorders across the lifespan.

Doctor of Audiology (Au.D.)

The clinical doctorate degree established in the 2000s as the entry-level academic requirement for practicing audiologists.

C. C. Bunch, Ph.D.

An influential pioneer who contributed to early academic training programs in the 1940s incorporating the newly invented audiometer.

Certificate of Clinical Competence in Audiology (CCC-A)

A voluntary professional certification granted by ASHA confirming that an audiologist meets rigorous clinical training and continuing education standards.

Audiology Assistant

Support personnel who perform delegated clinical tasks under the direct direction and supervision of a certified or licensed audiologist.

Hearing Instrument Specialist

A state-licensed professional trained to evaluate common adult hearing loss and fit hearing aids, but who does not diagnose medical disorders or tinnitus.

Medical Audiology

A specialty focused on diagnostic assessments in medical settings, ototoxic monitoring, and newborn hearing screening programs.

Educational Audiology

A subspecialty working within school systems to manage hearing conservation, service listening devices, evaluate classroom acoustics, and support hard-of-hearing students.

Intraoperative Monitoring

A practice specialty utilizing electrophysiological equipment to evaluate cranial nerve function and neural health in real time during surgical procedures.

Ear Horn

A non-electric, funnel-shaped acoustic device used prior to the 20th century to funnel ambient sound waves directly into the external ear canal.