exam 1 Review Flashcards
What are the components of a sound wave?
wavelength, frequency, and amplitude
What is a wavelength?
one peak + valley (compression + rarefaction)
What is frequency?
number of wavelengths passing a certain point
True or False: Low frequencies have long wavelengths.
True
True or False: High frequencies have short wavelengths.
True
Define Amplitude.
difference between maximum and minimum pressure
How is amplitude mesaured?
decibels (dB)
What is amplitude also known for in sound?
Loudness
Describe the ear processing sound.
The movement of molecules in the air known as sound enters the external auditory canal. It travels to the beginning of the middle ear, the tympanic member where the ossicles are attached. There are 3 bones in the ossicle the hammer, anvil, and stirrup which vibrate. The stirrup connects the middle to the inner ear where the cochlea is located. The stirrup is attached to the cochlea and the fluid inside of it moves the cilia which then send electrical signals to the brain.
True or False: The cilia pick up lower frequencies first then the higher frequencies deeper in the cochlea.
False. The cilia picks up higher frequencies then lower frequencies.
True or False: The human ear range is 20 - 20,000 kHz.
True
Which Hz range is most sensitive to the human ear?
1000 - 4000 Hz
Define tinnitus
perception of sound when no external noise is present
Define listener fatigue
listeners experience symptoms of physical exhaustion triggered by sound abnormalities
Define equal loudness principle
we do no perceive sound all the same. we put more energy behind lower + higher frequencies
Describe Phase and two types of interferences.
Phase is the time of the relationship between two or more sound waves at a given point in their cycles. Two interferences are constructive and destructive. Constructive is when the wavelengths are in-sync. Destructive is when they are completely out of sync.
Describe a situation how phase problems occur.
sound cancellation, distortion, microphone too close
constructive interference
sound waves IN sync (C - constant)
destructive interference
sound waves OUT of sync (D - different)
Solutions to Phase
3-to-1 rule (1 ft. from source, 3 ft. from mics)
Define polarity
flipping the signal upside, compared to another
What are the types of transducing properties?
dynamic and condensor
Describe the process of a dynamic microphone.
A diaphragm is positioned at the front of the mic responding to the pressure of the sound waves which is also attached to a coil. The coil is around a magnet and vibrates to the changes in pressure resulting in a disturbance in the magnetic field. This induces a small electrical current into the coil of wire, which is the audio output signal.
List characteristics of dynamic microphones.
simple construction, inexpensive, produces low noise, good frequency response rate, flexible environment, rugged, extremely high SPLs
Describe the process of a condenser mic.
It consists of one charged diaphragm and oppositely charged backplate separated by insulated material creating space between the two plates. When responding to sound waves the diaphragm changes the distance between the backplate which alternates the electrical signal voltage build up generating a small electrical signal.
List characteristics of condenser mics.
phantom power, battery, fragile, expensive, excellent transient response, higher OUTPUT level, poor SPLs, quick changes, more accurate to high frequencies
List and describe the four pick-up patterns.
Omnidirectional (all-around), Bi-directional (two directions, front + back), uni-directional (one direction), cardioid heart shaped)
List the family of cardioid mics.
cardioid, super cardioid, hyper-cardioid, ultra-cardioid
Pros + Cons of Omnidirectional Mics.
Picks up sound evenly on all sides, used for ambience; unwanted background noise, picks up more reverb
Pros + Cons of Cardioid mics.
mainly one direction (front of mic), rejects unwanted sound; does not pick up sound well from the back of the mic.
List and describe the four types of stereo recording mics.
- coincident (X-Y) [mics toward each other, cardioids only]
- near coincident (french/ dutch) [mics pointed away from each other, cardioids only, bunny ears]
- mid-side [1 cardioid, 1 bi-directional side pointed]
- spaced [either 2 cardioid OR 2 omnidirectional facing the same source w/ distance between]
What is frequency response?
how accurately do microphones transduce the sound source
what are SPLs?
sound pressure levels