Transcript Document
C-15 Physics Sound 15.1 Properties of Sound • If you could see atoms, the difference between __________________is not as great. • The image below is exaggerated to show effect. The frequency of sound • We hear __________________as having different pitch. • A ________________sound has a low pitch, like the rumble of a big truck. • A _________________ sound has a high pitch, like a whistle or siren. • In speech, women have ________ ____________________ than men. Complex sound Common Sounds and their Loudness Loudness Every _______________, means the pressure wave is ____________ ___________________. Logarithmic scale Linear scale Decibels (dB) Amplitude 0 1 20 10 40 100 60 1,000 80 10,000 100 100,000 120 1,000,000 Sensitivity of the ear • How we hear the loudness of sound is affected by the __________ of the sound as well as by the __________ • The human ear is _________ ___________ to sounds between 300 and 3,000 Hz. • The ear is less sensitive to sounds outside this range. • Most of the ____________ that make up _________are between ________________Hz. How sound is created • The human voice is a complex sound that starts in the _______, a small structure at the top of your windpipe. • The sound that starts in the larynx is ___________________ ____________in the throat and mouth. • Different sounds are made by changing both the vibrations in the larynx and the shape of the openings. How sound is created • A _____________ is a device that is specially designed to __________ ___________________ • The working parts of a typical speaker include a ___________, a coil of _______, and a _______. Recording sound 1. A common way to record sound starts with a ______________. 2. The microphone transforms a ___________________ ____________with the same pattern of oscillation. 3. In modern digital recording, a sensitive circuit converts ________________________ values between 0 and 65,536. Recording sound 4. ______________ correspond to the amplitude of the signal and are _________________. ______________ __________________________ is a list of 44,100 numbers. Recording sound 4. To play the sound back, ______________________is read by a laser and converted into ____________ signals again by a second circuit which ________ the process of the previous circuit. Recording sound 6. The electrical signal is ___________ until it is powerful enough to _________________________and reproduce the sound. Sound Waves We know sound is a wave because: 1. Sound has both ___________and _________. 2. The ___________________is frequency times wavelength. 3. Resonance happens with sound. 4. Sound can be ___________, ___________ and ____________ and also shows evidence of ____________ and ________________. Sound Waves A ________________ is a wave of alternating high-pressure and low-pressure regions of air. Amplitude of sound • The amplitude of a sound wave is very small. • Even a loud 80 dB noise creates a ___________ ______________of only a few millionths of an atmosphere. The wavelength of sound The Doppler effect • The ________________________________ is called the Doppler effect. • It occurs when _____________________________less than the speed of sound. The speed of sound • The speed of sound in air is _________________ (660 miles per hour) at one atmosphere of pressure and room temperature (21°C). • An object is ____________ when it is moving slower than sound. The speed of sound • We use the term ________________to describe motion at speeds _________than the speed of sound. • A shock wave forms where the _________________. • The pressure change across the shock wave is what causes a very loud sound known as a ____________. The speed of sound • The speed of a sound wave in air _________________ _________________ _________________. • The speed of sound in materials is often ____________ than in air. Standing waves and resonance • Spaces enclosed by boundaries can create ______________ with sound waves. • The___________end of a pipe is a closed boundary. • An open boundary makes ________________ in the standing wave. • Sounds of different frequencies are made by _____________________________. • A particular sound is selected by designing the length of a vibrating system to be resonant at the desired frequency. Sound waves and boundaries • Like other waves, sound waves can be ___________________ ______________as they pass from one material to another. • Sound waves reflect from ______ surfaces. • Soft materials can _________sound waves. Fourier's theorem • Fourier’s theorem says any complex wave can be made from a _________ _______________ ______________ waves. Sound spectrum • A complex wave is really a sum of component frequencies. • A frequency spectrum is a graph that shows the amplitude of each component frequency in a complex wave. Sound, Perception, and Music • A single frequency by itself does not have much meaning. • The meaning comes from patterns in many frequencies together. • A sonogram is a special kind of graph that shows how loud sound is at different frequencies. • Every person’s sonogram is different, even when saying the same word. Patterns of frequency The brighter the sonogram, the ___________ the sound is at that ___________. Hearing sound • The ________ vibrates in response to sound waves in the _________. • The three delicate bones of the inner ear _________ ____________ of the eardrum to the side of the cochlea. • The _______ in the spiral of the cochlea __________ _______________that travel up the spiral. Sound • The nerves near the beginning see a relatively ________ __________ and respond to longer wavelength, low frequency sound. • The nerves at the __________________ of the channel respond to shorter wavelength, higherfrequency sound. Music • The pitch of a sound is _____________________ its frequency. Though pitch and frequency usually mean the same thing, the way we hear a pitch can be _______________________________ ____________________________ • Rhythm is a regular time pattern in a sound. • Music is a _____________________________ that we find pleasant. • Most of the music you listen to is created from a pattern of _________________________________. Consonance, dissonance, and beats • __________________ is the study of how sounds work together to create effects desired by the composer. • When we hear more than one frequency of sound and the combination sounds good, we call it _________________. • When the combination ________________or unsettling, we call it dissonance. Consonance, dissonance, and beats • Consonance and dissonance are related to beats. • When frequencies are far enough apart that there are no beats, we get consonance. • When frequencies are ________________, we hear beats that are the cause of dissonance. • Beats occur when _____________________, but not exactly the same. Harmonics and instruments • The ______________sounds different when played on different instruments because the sound from an instrument is not a _______________________. • The variation comes from the ________________, _________________ of the fundamental note.