Chapter 2: Sound and it's Measurement Flashcards
Elasticity of an Object
The springiness of an object
As the distance between molecules decreases, elasticity increases.
Brownian Motion
The rapid and random movement of air particles. As heat increases, particle velocity increases.
Compression/Condensation Phase
Molecules in the wave close together
Rarefaction Phase
Molecules in the wave are pulled apart.
Frequency
The number of cycles per second measured in hertz.
Period
Time to complete full cycle is known as a period.
Period= 1/frequency
As length of a wave increases the frequency
decreases
Resonant Frequency
The natural rate of vibration of a mass.
Instantaneous Velocity
The velocity of a sound wave at a specific moment
Sound Velocity
The speed with which a sound wave travels. As density of an object increases, so does its sound velocity
As temperature and humidity increase, sound velocity
increases
Wavelength
w= velocity of sound (v)/frequency (f)
Wavelengths decrease as frequency increases
Interference
-When more than one tone is introduced, there are interactions among sound waves
-Can result in cancelation or reinforcement of waves
Beats
-When two tones of almost identical frequency are presented (e.g., 1000 and 1003 Hertz), there is a noticeable increase and decrease in the resulting sound intensity.
-Changes in amplitude are perceived as beats
Fundamental Frequency
The lowest frequency within a complex wave
Periodic Sounds
complex sounds that repeat over time
Aperiodic Sounds
-vary randomly over time and do not have fundamental frequencies
-aperiodic sounds are perceived as noise
Harmonics
-Tones above the fundamental frequency or overtones
Formant
Peak of a speech wave
Impedance
The opposition a medium offers to the transmission of acoustic energy.
Impedance is determined by
resistance and reactance
Decibel
The unit of measurement of intensity used in acoustics and in audiometers
Audiometric Zero
The lowest sound intensity to stimulate normal hearing 0 dB
Sensation Level
The number of decibels of a sound above the threshold of a given individual. Presentation level - Threshold = SL
Threshold Level
The lowest level someone can hear at
Pitch
a term used to describe the subjective impressions of the “highness” or “lowness” of a sound
Frequency is the physical value
Loudness
a subjective experience for intensity
Intensity is the physical value
Localization
The ability to tell the direction from which sound comes without seeing the actual source of the sound. Reverberation (echoing) can interfere with this
Masking
When two sounds are heard simultaneously, the intensity of one sound may be sufficient to cause the other to be inaudible
