HCD 9/2 Hearing Science: Wave Basics, Amplitude, Frequency, and Period

Vocabulary flashcards covering the key terms and definitions from the lecture notes on wave basics, amplitude, frequency, period, sound definitions, and environmental factors.

Waveform

Graphical representation of a sound's amplitude over time; shows pressure or displacement changes but not the literal motion of air particles.

Amplitude

A physical quantity describing how far air particles are displaced or how much pressure changes; perceptually related to loudness; can be described as pressure, displacement, or intensity (often in dB SPL).

Instantaneous amplitude

The amplitude value at a specific point in the waveform (e.g., a = +4, b = -4 at particular times).

Maximum amplitude

The largest positive peak in the waveform.

Peak-to-peak amplitude

The distance between the highest positive peak and the lowest negative peak.

Frequency

Number of cycles per second (Hz); f = n/t, where n is the number of cycles and t is time in seconds.

Period

Time it takes to complete one cycle; the reciprocal of frequency (T = 1/f).

Hz (Hertz)

Unit of frequency equal to one cycle per second.

Sound

Two definitions: (1) Psychological sense-related sensation produced by stimulating the auditory system; (2) Physical disturbance of a medium that propagates as a wave.

Psychological definition of sound

The perceptual sensation produced by stimulating the auditory system, involving cochlear processing and brain centers.

Physical definition of sound

A disturbance of a medium (e.g., air) that propagates as a wave.

Medium

Substance through which a sound wave travels (air is the focus here).

Disturbance

A perturbation of the medium that starts the wave (e.g., vibrating diaphragm).

Vibratory force

The source's motion that drives the disturbance in the medium, propagating with the wave.

Elasticity

Restoring force that returns particles to their resting state, allowing the wave to pass energy along.

Compression

High-pressure region in a sound wave where air molecules are crowded together.

Rarefaction

Low-pressure region in a sound wave where air molecules are spread apart.

Pressure view

Plotting the waveform as air pressure versus time or distance; high pressure corresponds to compression, low pressure to rarefaction.

Pressure (as a waveform component)

Variation in air pressure associated with a sound wave, used to visualize the wave.

SPL (Sound Pressure Level)

Decibel measure of sound pressure relative to a reference pressure; standard reference is p_ref = 20 μPa in air.

dB SPL

Decibels relative to 20 μPa; the common unit for practical loudness measurements in introductory hearing science.

Reference pressure

20 microPascals (20 μPa), the reference pressure for dB SPL.

Loudness

Perceptual correlate of amplitude; how loud a sound seems to a listener.

Pitch

Perceptual correlate of frequency; higher frequency is perceived as higher pitch.

Frequency spectrum

Distribution of a sound's energy across different frequencies.

Frequency vs. pitch

Frequency maps to perceived pitch (higher f = higher pitch).

Room acoustics

Environmental factor describing how room properties affect sound propagation and perception.

Background noise

Unwanted ambient sound that can affect hearing and perception.

Reverberation

Persistence of sound in a space due to reflections, influencing perceived loudness and clarity.

Phase

The relative position of wave components; noted as not covered in this introductory class.

Two core reciprocal relations

Frequency and period are reciprocals (f = 1/T; T = 1/f); high frequency means short period, and low frequency means long period.