Exam 1 Study Guide

Question 1

Sound

Answer 1

Audible distance in a medium caused by a vibrating source.

Question 2

Vibration (free & damped)

Answer 2

Repeated back and forth motion as a result of interplay between two opposing forces (elasticity & inertia)

Question 3

Elasticity

Answer 3

The ability to recover from distortion of shape.

Question 4

Inertia

Answer 4

The tendency of an object to resist any change in its motion.

Question 5

Frequency

Answer 5

How fast an object is vibrating or the rate of back and forth motion. reported in cycles per second or Hz
* A Spectrum/Phase Spectrum graph shows frequency on the X axis and Amplitude or Phase on the Y axis

Question 6

Duration

Answer 6

Total amount of time the object vibrates; how long the vibration lasts from the first cycle to the final one.

Question 7

Period

Answer 7

The amount of time it takes to complete one cycle
The relationship between frequency and period is p=1/f
The longer the period is the lower the frequency is; the shorter the period, the higher the frequency.

Question 8

Phase

Answer 8

The position within a cycle of vibration relative to a circle.

Question 9

Amplitude

Answer 9

Is the size of vibration or the amount of displacement from the equilibrium.
*A waveform graph shows amplitude on the Yaxis and time on the Xaxis

Question 10

Simple Sound

Answer 10

Sound with energy at only one frequency; the simplest sound that can occur. AKA Pure tone, sine wave, simple harmonic motion, sinusoidal vibration.

Question 11

Complex sounds

Answer 11

The sum of two or more sine waves; sound with energy at more than one frequency

Question 12

Periodic Sounds

Answer 12

SImple or complex sound that repeats itself over time.

Question 13

Aperiodic Sounds

Answer 13

Sounds that do not repeat over time (transient or noise)

Question 14

Complex Periodic Sounds/Harmonic Sounds

Answer 14

Sounds that contain a series of frequencies that are related

Question 15

Fundamental Frequency

f(n)=f0 x n

Answer 15

The first harmonic; the lowest frequency in the harmonic series; the highest in amplitude of the harmonic series if the sound is a complex sound.

Question 16

Compression = high pressure

Answer 16

The area that the medium is compressed; therefore, a local region of higher than normal density exist

Question 17

Rarefaction = low pressure

Answer 17

The medium is stretched; a local region of lower than normal density exists

Question 18

Speed of Sound

Answer 18

In air = 344 m/s

In water 1400 m/s

Question 19

Wavelength = 1m

Answer 19

Wavelength (~): ~ =c/f
C = Speed of a Sound and F= Frequency
always going to = 1m

Question 20

Period vs Wavelength

Answer 20

Wavelength is a measure of distance

Period is a measure of time

Question 21

Frequency

Answer 21

A physical property of the acoustic signal, an event that can be measured by instruments: the number of cycles in a specified time.

Question 22

Intensity

Answer 22

Sound pressure: A physical property of the acoustic signal that can be measured by a sound level meter

Question 23

The Decibel

Answer 23

a measure of Sound Pressure

Question 24

The intensity of sound

Answer 24

Is the amount of energy (or amplitude of vibration) in the sound wave per unit area. (watts/cm2 or pascals)

Question 25

Two ways to compute decibels

Answer 25

Intensity Level (dB IL)
Sound Pressure Level (dB SPL)