Chapter 16 Cont. Sound Flashcards
What is required in order for sound to be transmitted
A medium
What is sound
A longitudinal wave created by a vibrating object
In what type of mediums can sound travel
Solids liquids gases
Region of increased air pressure due to compression
Condensation
Region where air pressure is slightly less than normal due to inward motion
Rarefaction
Frequency
Number of cycles per second that passes by a given location
Pure tone
A sound with a single frequency
Ultrasonic
Sound waves with frequencies above 20K hertz
Infrasonic
Sound waves with frequencies below 20 hertz
Pitch
The subjective quality of the frequency detected by the ear and interpreted by the brain
Pure tone with a large frequency
High pitched sound
Pure tone with a small frequency
Low pitched sound
What is the objective property of a sound wave
Pressure amplitude
Magnitude of the maximum change in pressure, measured relative to the undos turned or atmospheric pressure
Pressure amplitude
What is the subjective property of a sound wave
Loudness
Attribute of sound that depends primarily on the amplitude of the wave
Loudness
What is the elastic limit of a sound wave
Approximately 10^9 Hz
Through which medium does sound travel fastest and why
Solids bc solid particles are held together by large binding forces
Through which medium does sound travel slowest and why
Gases bc gas particles have virtually no binding forces between them
What is power
Amount of energy transported per second of a wave
The sound power that passes perpendicularly through a surface divided by the area of that suface
Sound intensity
What is the definition and value of the threshold of hearing
Smallest sound intensity that a uniform ear can detect
1 x 10^-12 W/m^2
What is the relationship between intensity and the distance from the source
Inversely proportional
What does the area stand for in the intensity equation
The area of the object, could be a square, sphere etc.
What is the measurement unit used when comparing two sound waves
Decibels
What are the properties that affect the speed of sound
Density
Elasticity
Temperature
How is the speed of sound affected by the density of the medium
The more dense the medium, the slower the speed and vice versa
AKA inverse relationship
How does the elasticity of the medium affect the speed of sound
The more elastic the medium, the faster the speed of sound
AKA direct relationship
How does the temperature of the medium affect the speed of sound
The hotter the medium, the faster the speed of sound
AKA direct relationship
How are beats formed?
Overlapping waves with slightly different frequencies
What is the beat frequency and how is it calculated
The number of times per second that the loudness rises and falls
Difference btw the two sound frequencies
Chord
Pattern of beat frequency
Consonant
Two frequencies sound pleasant together
Dissonant
Two frequencies sound unpleasant together
What is the ratio created by consonant frequencies
Numbers will be 5 or less
What is resonance
The forced vibration of an object by another oscillation, causing it to vibrate at the same frequency
What is the natural or resonant frequency!
Frequency at which resonance occurs
What does the natural or resonant frequency often cause
An amplification of vibration of the “driven” object
What occurs when a note is played on a musical instrument
Several standing waves are resonating within the instrument simultaneously
Harmonics
The frequencies corresponding to standing waves
What is the fundamental frequency
The loudest and lowest;
The note that you hear
Overtone
Higher and fainter
Other frequencies
Timbre
The quality of the sound determined by the number and relative intensities of the overtones produced
What does the timbre do to each instrument
Gives each instrument a unique sound
In terms of harmonics, what is the first overtone and it’s wavelength
It is the 2nd harmonic with a 2/2 wavelength
What kind of waves do sound waves create in tubes
Standing waves
How are standing waves created in a tube
The waves reflect off the ends of the tube (even if the ends are open) and the downward and upward waves combine to form a standing wave
What do the standing waves in both open ended tubes end in?
Antinodes
What type of standing waves do tubes only open at one end produce
Standing waves of odd harmonic frequencies
