H - Sound Theory Flashcards
longitudal wave
disturbance moving along the direction of a wave
transverse wave
disturbance moving perpendicular to the direction of a wave
cycle of a waveform
period of compression and rarefraction
compression
increase in air molecules above normal pressure level
rarefaction
decrease in air molecules below normal pressure level
amplitude is perceived as…..
the loudness of a wave
frequency is perceived as……..
the pitch of a wave
the frequency of a wave is
the pressure of a wave, the time it takes to complete a full cycle
an octave is a….
doubling/halving of frequency
ear tuning is when…..
different frequencies are perceived at different levels
speed of sound is affected by…..
density/ temperature/ altitude
higher density means sound travels……
sound travels faster
sound travels fastest in which order….. gases/liquids/solids
solids then liquids then gases
in warmer air sound travels….. than in colder air
sound travels faster
at higher altitude sound travels……
slower
reflection of sound waves….
sound bouncing back of a surface
diffraction of sound waves….
sound bending and changing directions§
absorption of sound waves…..
how sounds are lost as they reach an object
diffusion of sound waves…..
the scattering of sound waves
refraction of sound waves…..
the change in direction of sound waves
white noise is….
all frequencies played at the same volume
pink noise is…..
all frequencies played at the same perceived volume
middle A (4) is what frequency
440Hz
period/ time of a wave…..
how long it takes a frequency cycle to complete
wavelength is…..
the distance between 2 corresponding points. Distance travelled by a sound in one period……
phase is…..
the point at which a wave is within its cycle
beat frequencies are…..
a phase interference caused by close frequencies played simultaneously, creates a beating/pulsating sound.
a sine wave is….
a single frequency, with no harmonics. cannot be created naturally, only by tone generators and synths.
a triangle wave is…..
a sine wave, plus odd harmonics
a square wave is…..
a sine wave, with odd harmonics. similar to a triangle wave, but with more, and a different balance of, harmonics
a sawtooth wave is…..
sine waves stacked with odd and even harmonics
any wave shape/ sound can be created by (fourier analysis)….
stacking sine waves at different frequencies and amplitudes, which then form a harmonic series.
harmonics are….
overtones accompanying a fundamental, in direct mathematical relationship to the fundamental.
a higher amplitude makes the perceived frequency…..
flatter/ more linear
equal loudness contour is…..
how we perceive loudness, at different frequencies
the perceived loudness of sound is measured in…..
phons
the fletcher munson curve shows us…..
how our ears perceive different frequencies at different volumes.
what do spl meters do and what does it stand for…..
they are used to measure loudness, and stands for sound pressure level.
inter-aural amplitude differences are….
the amplitude/loudness differences between 2 ears.
inter-aural time differences are….
the phase differences between 2 ears.
inter-aural spectral differences are….
the frequency differences between 2 ears.
sound localisation is….
based on binaural functions and the location of the sound, and uses the differences between our two ears.
the precedence/ haas effect is….
a sound followed by another sound, separated by sufficiently short time delay. the sound is perceived as a single fused auditory image.
the first sound to arrive at the listeners ear will determine the direction from where the sound is travelling.
the doppler effect is…..
a pitch change based on a sound travelling towards you, past you, then further away.
sheperd’s tone is….
sound consisting of a superposition of sound waves, separated by octaves.
the mcgirk effect is….
visual imagery overriding what you hear.
the cocktail party effect is…..
the ability to focus on one auditory image, and one particular stimulus
the ear is a…..
transducer, as it converts acoustic energy into mechanical energy, then into electrical nerve impulses
what is the function of the outer ear
it protects from foreign objects, amplifies sounds, and is responsible for sound localisation.
what are the elements of the outer ear
the auricle (pinna), external auditory meatus and the tympanic membrane
what is the function of the auricle
collect and guide sounds into the ear canal
what is the function of the external auditory meatus
a pipe with which certain frequencies bounce around and increase in amplitude. it conducts sound waves to the tympanic membrane
what is the function of the tympanic membrane
receives sound vibrations, then transmits them to the auditory ossicles.
what is the function of the middle ear
transmit sound from the outer ear to the inner ear through mechanical vibration. converts vibrations via amplitude pressure into the fluid in the inner ear.
what does the middle ear consist of
the auditory ossicles/ the eustachian tube
what are the names of the bones that make up the auditory ossicles….
the malleus (hammer), the incus (anvil) and the stapes (styrup)
what is the function of the inner ear
to convert mechanical vibrations in electrical nerve impulses which are then sent to the brain. vibrations from the stapes cause the liquid in the cochlea to form ripples, which pass over hairs and cause the nerve impluses
what does the inner ear consist of
the cochlea, semi-circular canals, and the vestibular nerve.
the hammer is the….
malleus
the anvil is the…..
incus
the styrup is the…..
stapes
hearing loss is caused by….
damage to the hairs in the cochlea
tinnitus us….
ringing or buzzing sensation, the cause of which is found in the brains auditory cortex.
frequency is measured in….
hertz (Hz)
perceived loudness is measured in….
phons
Sounds below approx. 1 kHz are perceived as _____ when played at high levels
lower
Sounds above approx. 2 kHz are perceived as _____ when played at high levels
higher
If an object emitting sound waves is moving either toward or away from a stationary observer, how does that affect the frequency?
The soundwaves in front of the moving object bunch together and the sound waves behind the object spread out.
If the object is moving toward you the waves will be perceived at a higher frequency.
If the object is moving away from you, the waves will be perceived at a lower frequency.
what is sound
a fluctuation in air pressure, molecules vibrating our eardrums. pressure wave moving through molecules.
what is the speed of sound in 21C air…
344 m/s
human perception of frequency is….
pitch
a sounds timbre is caused mainly by its…..
harmonics
the range of human hearing is…..
20Hz - 20000Hz
the way a sounds amplitude changes over time is know as its…..
envelope
the human perception of hearing is….
non-linear
amplitude is measured in…..
decibels (dB)
what amplitude the range of voice most attuned to….
85dB
what is thought to be the perfect mixing volume, and why
80 - 85 db, as this is where our ears have the flattest response, without causing damage
the width of frequency effects….
our ears perceived loudness
Hertz is named after who? Why?
Named after Heinrich HertzHe was the first person to conclusively prove the existence of electromagnetic waves
When a sound is louder, how does it affect the frequencies?
As sound gets louder the frequency response becomes more linear—you perceive all frequencies more evenly rather than perceiving some frequencies as being louder than others
How do high frequencies react when diffracted?
They are highly directional either focusing as they pass through an opening or being blocked by an obstacle
How does density of a medium affect the speed of sound?
The more dense the medium, the faster sound travels. sound travels fastest in solids, then liquids, and more slowly in gasses
How does temperature affect the speed of sound?
Sound travels faster in warmer temperatures and slower in cooler temperatures
What is a zero crossing?
The centre line of zero amplitude in a sine wave that is reflected in DAWS
How does sound behave when reflected off a concave object?
Sound becomes more focused/stronger
What is the speed of sound at 0ºC?
331 m/s
What does the fundamental tone determine?
pitch
Do sine waves start in or out of phase and by how much?
Sine waves start in phase
Do cosine waves start in or out of phase and by how much?
Cosine waves start 90º out of phase
DEF: masking
when a sound is covered up by another, louder/more harmonically rich sound in the same frequency range
What are weighting networks?
Ways of measuring decibels which account for the Fletcher Munsen curve.
A Freq. Weighting (incl. Phon line reference)
weighting network designed to reflect the response of human hearing, generally shown in dB(A). Has the most dramatic frequency response referenced to the 40 Phon line used between 20-55 dB SPL
B Freq. Weighting (incl. Phon line reference)
Used to weight things of moderate volume referenced to the 70 Phon line used between 55-85 dB SPL
C Freq. Weighting (incl. Phon line reference)
used for louder volumes, above 80 dB referenced to the 100 Phon line used about 85 dB SPL
