topic 13: acoustical control Flashcards
____ is a science which deals with the production, control, transmission, reception and effects of sound in an enclosed space.
acoustics
____ is the human ear’s response to pressure fluctuations in the air caused by vibrating objects.
sound
Sound travels in space by a phenomenon called ____.
wave motion
_____ in air is similar to the motion of a ripple prduced by dropping a pebble into a water pond.
wave motion
What are the 3 types of sound?
- speech
- music
- noise
____ is used for daily communication.
speech
___ has melodic frequencies.
music
___ is unwanted sound.
noise
What are the 4 physical quantities of sound?
- frequency
- speed
- wavelength
- intensity
_____ is the number of sound ripples generated in unit time.
frequency (f)
The number of cycles that the air particles move back and forth in one second in a sound wave is called the ______.
frequency of the wave
The unit of frequency is _____ which is also termed Hertz (Hz).
cycles per second (c/s)
Hertz (Hz) is named after the Austrian physicist _____ (1857-94).
Heinrich Hertz
The ____ of sound in air has been measured as 344 m/sec (1,130 ft/sec).
speed (c)
What is the speed of light?
300,000 km/sec
What is the speed of sound in air?
1,240 km/hr
The speed of sound in air ____ with the frequency of sound or its loudness.
does not vary
The ____ and the frequency of sound are related to each other.
wavelength (λ)
____ is defined as the amount of sound power falling on (or passing through, or crossing) a unit area.
intensity
The unit of intensity is ____.
watt per square meter (W/m2)
What are the 2 charactersitics of sound?
- loudness
- pitch
____ is a measure of the intensity of sound and is expressed in decibels (dB).
loudness
____ is a quantity called the sound intensity level (IL).
loudness
____ is the frequency of sound wave perceived by the human ear.
pitch
A high-pitched sound means that it has a _____ frequency.
high
What are the 2 activities involves in noise control?
- the control of air-brone noise through the insulation of sound or the shuttin-out of unwanted sounds from the outside
- the control of structure-borne noises, through the isolation of machines from the room’s or the building’s structure
What are the 5 principal acoustical defects of rooms?
- prolonged reverberation
- echo
- resonance
- flutter echo
- undue focusing of sound
_____ is long reverberation time (RT) due to large amounts of highly reflective surfaces and/or to large volume of space which will take considerable time for reflected sound to die out.
prolonged reverberation
Effect of prolonged reverberation is ____ which is harmful to both speech and music.
burring
What are the 3 factors that influences reverberation?
- volume of the room
- sound absorbing qualities of the room’s surface
- number of people and furniture in the room
______ is the distinct reflection of original sound which results when the path of reflected sound is 20 m (65 ft) or more than the path of direct sound.
echo
If the difference is _____ than 20 m, the reflected sound will reinforce the direct sound which is desirable.
less
____ is the reinforcement of certain sound frequencies due to sympathetic vibrations.
resonance
The effect of ____ would be to emphasize certain frequencides at the expense of others, which is undersirable for balance desired in rooms intended for music.
resonance
____ is a rapid but repetitive succession of sounds caused by highly reflective parallel surfaces (wall to wall, or ceiling to floor).
flutter echo
____ is caused by concave surfaces which causes sound to converge at certain points with resulting loss of energy in other parts of the room.
undue focusing of sound
