Intro to Audiology: Sound Measurement

(deci) Bel

An arbitrary logarithmic unit used to represent sound amplitude on an interval scale.

1 kHz = 1000 Hz

1 second = 1000 ms

Acoustics

The study of the physics of sound.

Amplitude

The maximum displacement of the particles of a medium; the distance between the baseline and the maximum displacement. (Loudness)

Amplitude

The measure of the strength or magnitude of the sine wave.

Aperiodic Wave

A wave with an absense of periodicity, where it is impossible to predict what the wave will look like from one time to the next. Its vibratory motion is random.

Complex Wave

Any sound that is not sinusoidal; it itself is composed of a series of simple sine waves that can differ in amplitude, frequency, and phase.

Energy

The measure of the capacity to do work OR something that can produce a change in matter.

Fourier Analysis

Takes a complex wave form and decomposes/analyzes it to determine the amplitudes, frequencies, and phases of its sine wave componants.

Frequency

The number of cycles compled per second. (Pitch)

Frequency = 1/p

Fundamental Frequency (F0)

The first harmonic.

Harmonics

All of the sinusoids in a harmonic series.

Logarithmic Scale

One unit on the scale is so many times greater (or less) than another; successive units are always different by some constant ratio, and the constant ratio always equals the base.

Mass

The amount of matter that is present.

Period

The time (seconds) it takes for a vibration to complete one cycle of vibration.

Period = 1/f

Periodic Wave

A wave that repeats itself at regular intervals over time.

Simple Harmonic Motion

Sinusoidal Motion (a sine wave form).

Waveform

A graph in which changes in pressure or amplitude (displacement), are shown as a function of time.

Wavelength

The distance traveled by a sound wave during one period of vibration.

Work

The force applied times the distance moved.

dBIL (Intensity Level)= 10 x log(n/reference)

dbSPL (Sound Pressure Level) = 20 x log(n/reference)