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89 Cards in this Set

  • Front
  • Back
What is amplitude?
The extent of vibratory movement of a mass from its position of rest to that point farthest from the position of rest.
What is Anechoic Chamber?
A specially built room with large wedges of sound absorbing material on all walls, floor and ceiling whose purpose is to provide maximum sound absorption and to keep reverberation to an absolute minimum.
What is an aperiodic sound?
A complex sound that varies randomly over time and does not have a fundamental frequency.
What is an artificial ear?
A device for calibrating air--conductino earphones. it consists of a 6 cm3 coupler to connect an earphone to an condenser microphone with cathode follower and a meter that reads in dB SPL. When calibrating insert earphones, a 2cm3 coupler must be used.
What is an artificial mastoid?
A device for calibrating bone-conduction vibrators consisting of a resilient surface that simulates the vibrating properties of the mastoid process of the skull and an accelerometer. It is connected to a meter that reads in either decibels or units of force.
What is an Audiometer?
A device for determining the thresholds of hearing. Pure tones at various frequencies are generated, and their levels are increased and decreased until thresholds are found. Outputs may include earphones for air-conduction testing, a bone-conduction vibrator for bone-conduction testing, and one or more loudspeakers for sound-field testing.
Periodic variations of the amplitude of a tone when a second tone of slightly different frequency is produced simultaneously.
A unit for expressing ratios of sound pressures in base 10 logarithms.
Brownian motion
The constant random colliding movement of molecules in a medium.
The reduction of the amplitude of a sound wave to zero. This results when two tones of the same frequency and amplitude are introduced 180 degrees out of phase.
Complex Wave
A sound wave made up of a number of different sinusoids, each with a different frequency.
Complex wave?
A wave made up of a number of different sinusoids, each with a different frequency.
A pure tone constituent of a complex wave
The portion of a sound wave where the molecules of the medium are compressed together
Cosine Wave?
A soundwave representing simple harmonic motion that begins at 90 degrees.
The complete sequence of events of a single sine wave through 360 degrees
Progressive diminution in the amplitude of a vibrating body. Heavy damped=amplitude decays rapidly. Lightly damped=amplitude decays slowly. Critcally damped=all vibration ceases before completion of 1 cycle.
A unit for expressing the ratio between two sound pressures or two sound powers; one tenth of a Bel.
Difference Tone
The perceived pitch of a tone resulting from the simultaneous presentation of two tones of different frequencies. The tone perceived has a frequency equal to the difference in hertz between the other two tones.
A unit of force just sufficient to accelerate a mass of 1 gram by 1 cm/sec2
The ability of a mas to return to its natural shape.
A unit of work. One erg results when 1 dyne force displaces an object by 1 centimeter.
A logarithm, or power to which a number may be raised
The impetus required to institute or alter the velocity of a body
Forced Vibration
The vibration of a mass controlled and maintained by an external impetus.
A peak of energy in the spectrum of a vowel sound
Fourier Analysis
The mathmatical breakdown of any complex wave into its component parts, consisting of simple sinusoids of different frequencies.
Free field
An acoustic environment with no reverberating surfaces.
Free vibration
The vibration of a mass independent of any external force.
The number of complete oscillations of a vibrating body per unit of time. In acoustics the unit of measurement is cycles per second or Hertz
Fundamental Frequency
The lowest frequency of vibration in a complex wave.
Any whole-number multiple of the fundamental frequency of a complex wave. The fundamental frequency equals the first harmonic.
Hearing Level
The number of decibels above an average normal threshold for a given signal. The hearing-level dial of an audiometer is calibrated in dB HL>
Cycles per second
Opposition to sound wave transmission. Comprises the frictional resistance, mass and stiffness and is influence by frequency.
The amount of sound energy per unit of area.
Intensity Level
An expression of the power of a sound per unit of area. The reference level in decibels is 10 -12 watt/m2 or 10 -16/watt/cm2
Inverse Square Law
The intensity of a sound decreases as a function of the square of the distance from the source.
The work obtained when a force of one Newton displaces an object one meter. (One J is equal to 10 million ergs)
Kinetic energy
The energy of a mass that results from its motion
The ability to determine the specific location of a sound source
Loudness Level
The intensity above the reference level for a 1000 Hz tone that is subjectively equal in loudness. The unit of measurement is the phon.
The process by which the threshold of a sound is elevated by the simultaneous introduction of another sound.
The quantity of a body as measured in terms of its relationship to inertia. The weight of a body divided by its acceleration due to gravity.
Mass reactance
The quantity that results from the formula: two times pi times frequency times mass.
Exponent that tells the power to which a number is raised; the number of times that a number (the base) is multiplied by itself.
Longitudinal Wave
A wave in which the particles of the medium move along the same axis as the wave
The subjective impression of the power of a sound. The unit of measurement is the sone.
A unit of pitch measurement. One thousand mels is the pitch of a 1000 Hz tone at 40 db SL, 2000 mels is the subjective pitch exactly double 1000 mels, and so on
A pressure equal to one-millionth of standard atmospheric pressure. 1 bar equals 1 dyne/cm2.
The force required to give a one kilogram mass an acceleration of 1 m/sec2. 1 N equals 100,000 dyne
The difference between two tones seperated by a frequency ratio of 2:1
A unit of impedance
The back and forth movement of a vibrating body
Any whole-number multiple of the fundamental frequency of a complex wave. it differs from the harmonic only in the numbering used. The first overtone is equal to the second harmonic.
A unit of pressure equal to 1 N/m2
The duration of one cycle of vibration. (per second) The period is the reciprocal of frequency...the period of a 1000 Hz tone is 1/1000 second
Periodic wave
A complex sound that repeats over time.
The relationship in time between two or more waves.
The unit of loudness level. It corresponds to the loudness of a signal at other frequencies equal to the intensity of a 1000 Hz tone.
The subjective impression of the highness or lowness of a sound; the psychological correlate of frequency.
Potential energy
Energy resulting from a fixed and relative position, as a coiled spring.
The rate at which work is done. Units of measurement are watts or erg/second
Force over an area of surface
Pure tone
A tone of only one frequency (no harmonics)
The sharpness of resonance of a sound system; the vividness or identifying characteristics of a sound; the subjective counterpart of a spectrum; timber
That portion of a sound wave where the molecules become less densly packed per unit of space
The mathematical result of a quantity divided by another quantity of the same kind, often expressed as a fraction
The contribution to total acoustic impedance provided by mass, stiffness, and frequency
The opposition to a force
The ability of a mass to vibrate at a particular frequency with minimum application of external force
Resonant frequency
The frequency at which a mass vibrates with the least amount of external force; the natural frequency of vibration of a mass
A short-term echo, or the continuation of a sound in a closed area after the source has stopped vibrating, resulting from reflection and refraction of sound waves
Sensation Level (SL)
The number of decibels above the hearing threshold of a given subject for a given signal.
Sine Wave/Sinusoidal
Waveform of a pure tone showing simple harmonic motion
The unit of loudness measurement. One sone equals the loudness of a 1000 Hz tone at 40 dB SPL
Sound-level meter
A device designed for measurement of the intensity of sound waves in air. It consists of a microphone, an amplifier, a frequency-weighting circuit and a meter calibrated in decibels with a reference of 20 micropascals
Sound pressure level (SPL)
An expression of the pressure of a sound. The reference level in decibels is 20 micropascals
The sum of the componenets of a complex wave.
The flexibility or pliancy of a mass. The inverse of compliance.
Stiffness Reactance
The quantity that results when the stiffness of a body is divided by two times pi times frequency.
The level at which a stimulus is barely perceptible.
Transverse wave
A wave in which the motion of the moecules of hte medium is perpendicular to the direction fo the wave
The speed of a sound wave in a iven direction
To and fro movement s of a mass.
A unit of power
A series of moving impulses set up by a vibration
The distance between the exact same point on two successive cycles of a tone
Energy expended by displacement of a mass. The unit of measurement is an erg or joule