# Shared Flashcard Set

## Details

Unit 7
Sound
42
Physics
11/21/2012

Term
 What is sound?
Definition
 a wave produced by vibrating objects/substances
Term
 What kind of wave is sound?
Definition
 mechanical and longitudinal
Term
 The frequency of sound waves are equal to_________________.
Definition
 The frequency of the vibrating objects
Term
 What is pitch?
Definition
 Frequency of sound
Term
 What is the range of human hearing?
Definition
 20Hz-20kHz(20,000Hz)
Term
 What is an infrasonic sound?
Definition
 a sound with a pitch below 20Hz
Term
 What is an ultrasonic sound?
Definition
 A sound above 20kHz
Term
 How does sound travel?
Definition
 Sent out in all directions from the vibrating source.
Term
 What is an elastic material?
Definition
 changes shape in respond to applied force, the returns to its origional shape once forces are removed. Elastic materials transmits sound well.
Term
 Why does sound travel best in solids?
Definition
 Solids are dense. They have particles closely packed. When vibrations hit the particles , the particles hit each other easier. Hence, sound travels faster.
Term
 What is the speed of sound?
Definition
 330m/s
Term
 What frequency sounds travel further?
Definition
 lower frequency=further distance
Term
 What happens when sound hits a surface?
Definition
 Some sound is absorbed, some is reflected.
Term
 What is reflection of sound called?
Definition
 Echo
Term
 What do you call it when many echos combine and makes sound garbled?
Definition
 reverberations
Term
 What are acoustics?
Definition
 study of how sound interacts with surfaces and rooms
Term
 Any elastic object will vibrate at its own frequency when disturbed. What is this called?
Definition
 Natural frequency
Term
 What happens when frequency of forced vibrations on an object matches its natural frequency?
Definition
 dramatic increase of amplitude occurs(aka. resonance)
Term
 What are the three characteristics of music?
Definition
 1. Pitch2. Loudness3. Quality
Term
 What is pitch?
Definition
 frequency of sound
Term
 What is intensity?
Definition
 amount of change in pressure
Term
 What are the units of intensity?
Definition
 decibels (dB)
Term
 What is the threshold of hearing?
Definition
 0dB
Term
 What is loudness?
Definition
 sensation that may differ when various people are exposed to the same sound. Loudness is perceived.
Term
 What is quality?
Definition
 allows us to distinguish one instrument from another
Term
 What are overlapping tones?
Definition
 Partial tones
Term
 What is the lowest frequency that determines the pitch of the note called?
Definition
 Fundamental frequency
Term
 What are partial tones whose fundamental frequencies are whole multipliers of the fundamental frequency are called ____________.
Definition
 Harmonics
Term
 What is an analog recording?
Definition
 recorded signal is continuously variable
Term
 Air pressure vibrations are converted into an electrical signal that has a current or voltage directly proportional to the air pressure at each instant. What devise is used for this?
Definition
 Microphone
Term
 The changing current/voltage will alter the magnetization of a tape or the displacement of a groove on a record cutter to record the sound. True False
Definition
 True
Term
 What is a digital recording?
Definition
 the physical properties of the sound are converted into a series of numbers
Term
 In nature, what type of sound is sound? (awkward phrasing sorry)
Definition
 analog
Term
 What has to be attached to a microphone?
Definition
 analog-to-digital converted
Term
 After converted to digital, what happens to sound?
Definition
 the sound is then put into a compact disc/hard drive
Term
 what is a stereo recording?
Definition
 two microphones. two speakers. (may be two or more n some cases)
Term
 What is mono?
Definition
 one microphone. one speaker.
Term
 What is mixing?
Definition
 part of recording process. all of the different instruments and voices combined into one finalized sound.
Term
 How do you convert digital to analog?
Definition
 Use a digital-to-analog converter
Term
 When is this step not necessary?
Definition
 If the signal starts from a LP/record or tape
Term
 What is an amplifier?
Definition
 devise that increases amplitude
Term
 What is the amplifier connected to, that creates air pressure variations directly proportional to to current of the amplified signal?
Definition