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Acoustics Pt. 1
Speech Science: Exam 1
Question | Answer |
---|---|
Acoustics | The study of sound |
Sound is the _______ we feel when acoustic energy enters our auditory system | Sensation |
For something to be heard there needs to be a _________ | Source and a medium |
Acoustic energy is energy in form of __________________ that carry the energy from one place to another | Oscillating (vibrating) particles in a medium |
________ is the same thing as sound | Acoustic energy |
Sound | A disturbance in a medium. The disturbance produces a wave that travels through space |
_________ goes from point A to point B, but NOT a specific particle | Acoustic energy |
Most common medium is through _______ | Air |
Macroscopic view | An ocean wave where the surface shows a succession of curves |
Microscopic view | The wave is about the particles |
Newton’s First Law of Motion | Once a particle transfers its energy to the next particle, it will remain in uniform motion and gradually the motion will die because of resistance |
Speed of sound | The distance travelled per unit time by a medium |
The speed of sound varies from __________ | Substance to substance |
The speed of sound is measured in? | Meters/seconds |
In common everyday speech, speed of sound refers to? | The speed of sound waves in air |
Cycle | Each individual vibration |
Frequency (f) | The number of cycles completed in 1 second |
Frequency is measured in? | Hertz (Hz) |
Period (T) | The time taken for each cycle to complete |
Wavelength (λ) | Distance travelled by the wave in 1 period (peak-to-pea distance) |
Wavelength (λ) is measured in? | Meters (m) |
Amplitude | The size or magnitude of a vibration |
Amplitude ______ over time as energy is lost due to friction | Decreases |
Damping | Dying out of a vibration over time |
Period (T) is time in? | Seconds to complete a cycle |
Frequency (f) is cycles per | Second |
Period formula: | T = 1/f |
Frequency formula: | f = 1/T |
If the frequency = 20 Hz, what is the period? | T = 0.05 seconds |
If the period = 0.005 s, what is the frequency? | f = 200 Hz |
(Sound waves) Simple | Only one frequency (a pure tone) |
(Sound waves) Complex | Multiple frequencies (all other sounds including speech) |
Complex waves are made up of a combination of __________ | Simple waves |
(Sound waves) Periodic | One pattern that repeats itself |
(Sound waves) Aperiodic | No repetitive pattern (white noise) |
Periodic waves and aperiodic waves can be __________ | Complex waves |
Simple waves MUST be _________ | Periodic |
The simplest form of sound vibration is produced by | Simple harmonic motion |
Simple Harmonic Motion (SHM) is ______ | Periodic |
With Simple Harmonic Motion (SHM), the period of the oscillation _________ | Stays constant |
With Simple Harmonic Motion (SHM), the frequency is __________ | Constant |
The graphic representation if Simple Harmonic Motion (SHM) is a _______ | Sine wave |
In Simple Harmonic Motion (SHM) the restoring force is | Proportional to its displacement |
Elasticity (restoring force) can also be referred to as _________ | Potential energy |
Inertia can be referred to as | Kinetic energy |
Inertia and restoring forces (RF) vary continuously during cycle: ______ is stronger when ______ is weak (when times are more displaced); _____ is strong when _______ is weak (around rest position); Interplay between the two forces lets vibration persist | Restoring forces, inertia, inertia, resting forces |
When displacement is maximum (the swing is far out to the left or right), _______ is strong, pushing the swing back _______ | Restoring forces, downward |
When displacement is maximum (the swing is far out to the left or right), _______ is momentarily zero as the swing __________ | Inertia, stops and reverses |
When displacement is zero, ________ is strong. The fastest movement occurs? | Inertia, The swing passes the rest position |
When displacement is zero, ________ is momentarily zero when? | Resting forces, the swing passes through the rest position |
(Tuning fork example) Initial impact (your finger touches it) starts movement (________) away from the rest | Displacement |
(Tuning fork example) _______ allows displacement, but it also causes them to slow down and reverse direction. The tuning fork wants to resume its original shape | Elasticity |
(Tuning fork example) As the prongs move outward again, they overshoot their original position due to _______ | Inertia |
(Tuning fork example) However, ________ causes them to slow down, stop momentarily and reverse direction again | Elasticity (resting force) |
(Tuning fork example) They pass their original position (due to inertia) and the entire pattern _________ | Repeats itself |
The angle in SHM corresponds to the real angle through which the ball has moved in a circulation, this is called the _________ | Phase angle |
The uniform _________ motion is intimately related to SHM | Circular |
What is Newtons First Law of Motion? | When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a net force |
What is Newtons Second Law of Motion? | In an inertial reference frame, the vector sum of the forces F on an object is equal to the mass (m) of that object multiplied by the acceleration vector a of the object |
What is Newtons Third Law of Motion? | When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body |
Longitudinal waves | Particles vibrate alternately in the same or opposite direction or propagation (away from/back toward the source) |
(Longitudinal Waves) Particles approaching and receding from each other create _________ | Pressure variations |
(Longitudinal Waves) Rarefactions and _______ | Compression |
(Longitudinal Waves) Sound in air is _________ | Longitudinal |
_________ is longitudinal | Speech |
Transverse waves | Particles vibrate at right angles to the direction of the wave propagation and particles bob up and down as the wave moves across the water |
Complex sounds | Multiple waves patterns from simultaneous sounds |
Multiple frequencies from complex sounds are transmitted | Simultaneously |
(Complex sounds) _________ created by waves bouncing off of objects | Reflected waves |
(Complex sounds) Adding _____________ together may yield a complex period sound | Periodic sounds |
Phase | Describes how cycles relate to each other |
In phase | Waves crest and trough at same time |
Out of phase | Waves crest and trough at different times |
Constructive interference | Addition of waves in phase yields high amplitudes |
Destructive interference | Addition of waves out of phase yields cancellation |
Complex periodic sounds contain _______________ and repeats itself over time | Two or more frequencies |
The lowest frequency of a complex periodic sound is the ___________ | Fundamental frequency (fo) or first harmonic (H1) |
(fo) represents? | Vibration along the whole length of the vibrating body |
Higher harmonics reflect? | Shorter vibrating segments within the vibrating body |
H2 represents? | Vibration along 1/2 vibrating body |
H3 represents? | Vibration along 1/3 vibrating body |
H₁ (F₀) = | 100 Hz |
H₂ = | 2 × F₀ = 2 × 100 Hz = 200 Hz |
H₃ = | 3 × F₀ = 3 × 100 Hz = 300 Hz |
Higher harmonics are mathematically _________ (whole number multiples) to H1 (fo) | Related |
Waveform | Time on x-axis, amplitude on y-axis |
Waveform shows overall _________ of complex wave | Amplitude |
(Waveform) ___________ not directly represented | Individual harmonics |
Spectrum | Frequency on x-axis, amplitude on y-axis. A sound spectrum displays the different frequencies present in a sound |
Spectrum shows the amplitude of each _________ | Harmonic |
(Spectrum) Shows a single _______________ - no time-varying information | Time slice only |
Spectrum is obtained by? | Fourier analysis |
Fourier analysis | Analyzing complex waves into simple components |