AET: Test 1 Questions and Answers 100% Pass

AET: Test 1 Questions and Answers 100% Pass sound: physically it can be defined as longitudinal waves set into motion through a gas, liquid, or solid sound: psychologically it's human response omnidirectional travels in all directions Can sound travel through a medium? Yes Music - Audio recording, mixing/mastering, live sound Sound for Media - Audio film, broadcast tv, video games, internet, radio Physics - Audio acoustics: sound/concert design, electro acoustics: microphone and loud speaker design Hearing Science - Audio auditory system, sound perception, hearing loss and assistive technology Computer Science - Audio music software, mobile apps, web audio, music streaming Electrical Engineering - Audio audio circuits: amps, pedals, consoles, digital signal processing: digital effects, synthesis How does sound begin? as a vibration What is medium for a sound wave? air Can sound travel through a vacuum? no, there's no medium Can sound travel through light? yes, there's a medium What does sound have to do with the brain? it's the relationship b/t the brain's perception and interpretation 5 components of sound: 1. frequency 2. amplitude 3. velocity 4. wavelength 5. phase frequency the number of cycles that a vibration completes in one second What is frequency measured in? hertz pitch how we hear frequency True/False: The higher the frequency, the higher the pitch. True amplitude energy of a sound wave What is amplitude measured in? dB (decibels) velocity the speed of a sound wave (frequency x wavelength) (v=Fx2) wavelength the distance a sound wave travels to complete one cycle of compression and rarefaction phase the time relationship between between 2 or more sound waves at a given point in their cycles waveform a graphic representation of a sound wave's compression and rarefaction patterns, usually shown as amplitude and time sine wave the simplest wave form compression when energy forces molecules together rare faction when energy forces molecules apart hertz # of cycles in one second Which of these is closest to the length of a 1kHz sound wave in physical space? 1 foot Where does the human ear hear the best? upper midrange Humans can hear a __________ octave range. 10 human's range 20Hz-20,000Hz octave doubling of frequency an octave above 125 Hz is: 250 Hz How do we interpret amplitude? volume The ratio unit we use for measuring amplitude is: dB dB-SPL a measure of sound pressure level 140 dB = threshold of pain 0 dB = threshold of knowing 120 dB = threshold of feeling 60 dB = average conversation sound travels through air at ______________ 1130 feet per sec. The speed of sound at sea level, 70 - degrees Fahrenheit is: 1130 feet per sec. higher frequencies = shorter lower frequencies = longer example of wavelength: 125 Hz wave 1130/125= 9.04 constructive interference increasing amplitude where compression and rarefaction occur at the same time destructive interference decreasing amplitude where compression and rarefaction occur at the same time direct sound tells us the location, size, and timbre of the source early reflections the same sound reflected off nearby surfaces; tells reflectivity, size, etc. reverberant multiple early reflections becoming smaller and combining energy timbre most sounds other than sine waves are made up of more than 1 discrete frequency chances in level = sound envelope attack build up when sounded (to peak) decay time for the sound to reduce after initial peak sustain constant volume after decay until release sound provides - cognitive information knowledge, judgement sound provides - affective information emotion, feeling transducer converts energy from one form of energy to another; responds to pressure variations produced by sound and generates impulses processor analyzes/interprets impulses pinna outer ear (sound is collected here) The ossicles bones ("hammer/anvil/stirrup") : amplify the sound pressure and protect the ear from intense pressure cochlea fluid filled; lined with tiny hair receptors or cilia cochila shaped like a snail, and is responsible for converting mechanical vibrations into electrical impulses auditory nerve carries impulses to the brain and is interrupted as sound Tiny hair-like projections called ________________, transform mechanical vibrations into electrical and chemical signals, which are sent to the brain. cilia the ear is ___________________. nonlinear The way our ears hear sounds "non linearly" was discovered and graphed by: Fletcher and Munson masking when louder sounds hide softer sounds beats produced when 2 tones differ only slightly in frequency and have similar amplitude combination result when 2 tones differ by more than 50Hz hearing loss afflicts 1 in 9 people in the U.S.; 1 in 5 teenagers exposure to loud sound for extended periods of time can cause: TTS ways to take care of your hearing: avoid/minimize hazardous sounds, wear headphones, get hearing checked, frequent breaks binaural three-dimensional spatial localization = perception of direction inter-aural arrival time differences and intensity differences pina vertical localizing When localizing a sound (determining the direction the sound is coming from), our two ears use THREE mechanisms to localize the sound source. They are... Pinna Reflection, Arrival Time, Intensity We don't hear as well _______________ and don't do as well ___________________. behind us, vertically temporal fusion reflections within 30ms are fused w/ direct sound; perceived as "one source" Haas Effect apparent location of source when the sound is heard from 2 sources but arriving at different times True/False: Temporal fusion, or the "Haas" effect, occurs when a sound is perceived as coming from "one source", but the sound is actually coming from 2 sources, with one arriving less than 30 ms LATER than the first sound. True reverberation reflections off of many boundaries "Direct Sound", "Early Reflections", and "Reverberation" make up what we call the Life Cycle of Sound reverb time (Rt - 60) RT60 is defined as... the amount of time for sound to "die away" by 60 dB acoustics sound in a room __________________________ deals with the human perception of sound, and our subjective responses to sound waves. psychoacoustics reflection of sound = reflects off of surfaces concave curving inward convex curved outward diffusion of sound scattering of sound in all directions True/False: Diffusion is the absorbing of a sound by soft materials in the room. False If sound bends or spreads around a surface, it is said to be: Diffracted Are low end sound waves more difficult to control than the high end sound waves? Yes True/False: The best way to listen to a binaural head recording is by sitting directly between 2 loudspeakers. False