Unit 1 Review: Sound, Acoustics, and Signals

Vocabulary flashcards covering fundamental sound terminology, acoustics, signal processing, measurement scales, and high-yield physical relationships.

Free Field

A sound field in which sound travels without significant reflections or obstacles, such as in an anechoic chamber.

Diffuse Field

A sound field in which sound arrives at a location from many directions because of reflections.

Wavelength ($\lambda$)

The physical distance of a sound wave cycle, determined by the equation $\lambda = \frac{c}{f}$ where $c$ is speed of sound and $f$ is frequency; inversely proportional to frequency.

Decibel Scale

used to represent an extremely large range of sound intensities using manageable numbers, where equal changes in $\text{dB}$ represent ratios rather than equal linear changes in physical intensity.

Periodic Sounds

Waveforms that repeat themselves over time, containing a fundamental frequency and harmonically related frequency components.

Aperiodic Sounds

Waveforms that do not repeat regularly over time, with noise being a common example.

Aliasing

Signal distortion occurring when the sampling rate is too low, causing higher-frequency components to be incorrectly represented as lower frequencies.

Evidence-Based Practice (EBP)

Clinical decision-making integrated by combining best available research evidence, clinical expertise, and patient or client values, preferences, and circumstances.

Nominal Scale

A measurement scale consisting of categories with no meaningful order, such as type of hearing aid.

Ordinal Scale

A measurement scale consisting of categories with a meaningful rank or order, such as mild, moderate, or severe.

Interval Scale

A measurement scale with equal intervals between values but no true zero, such as temperature in $^\circ\text{C}$.

Ratio Scale

A measurement scale featuring equal intervals and a true zero point, such as frequency in $\text{Hz}$.

Nyquist Theorem

The principle stating that the sampling rate must be at least twice the highest frequency in the signal ($\text{Sampling Rate} \ge 2 \times \text{highest frequency}$) to accurately represent it.

Diffraction

The bending or spreading of a sound wave around an obstacle or through an opening, which occurs more effectively for longer wavelengths.

Analog Signal

A continuous signal that can take on an essentially infinite number of values over time.

Digital Signal

represented using discrete numerical values obtained by sampling and quantizing an analog signal.

Sine Wave Characteristics

The four defining characteristics: Frequency (cycles per second in $\text{Hz}$), Amplitude (magnitude/strength), Phase (position within a cycle in degrees), and Period (time required for one cycle).

Period

The amount of time required to complete one cycle of a wave, related to frequency ($f$) by the formula $T = \frac{1}{f}$.

Mass / Inertia (Medium Property)

A required property of a medium where particles resist changes in motion, allowing mechanical energy transfer.

Elasticity / Stiffness (Medium Property)

A required property of a medium where particles return toward their original resting position after displacement.

Simple Harmonic Motion

Repetitive back-and-forth motion around an equilibrium or resting position, classically represented by a sine wave.

Sound Pathway to the Brain

The complete pathway from speaker emission to perception: Speaker \rightarrow Air \rightarrow Hearing Aid Microphone \rightarrow Processing \rightarrow Receiver \rightarrow Ear canal \rightarrow Tympanic membrane \rightarrow Ossicles \rightarrow Cochlea \rightarrow Hair cells \rightarrow Auditory nerve \rightarrow Brain.

Measurement Scales Overview (Nominal, Ordinal, Interval)

A reference table outlining measurement scale classifications, meanings, and examples for nominal, ordinal, and interval scales.