Do computer-based demos/hands-on activities; answer "Application" questions, PSLG pp. 72-74. -- One-day "Sounds Cool" lesson plan: Show Bill Nye video, "Sound" (~24 min.). Highlight oscilloscope and mixer used by rock band, "Sound Garden." - cardboard simulated ear of science - connected to oscilloscope (note transverse waves) - "Sound Garden" segment - model eardrum: salt on plastic - 1/100 sec time to process sound (ear-to-brain) - frequency versus pitch - Leonard Crackerwagon, Mr. Sound Effects - ultrasound (beyond sound), unborn baby - natural frequency / resonance (at natural frequency) - Gloria Wavelength and the Vibrations "Sound is a Vibe" -- "The Science of Music" pitch - low & high rhythm - pattern of beats [volume] loudness - musical notes - tune musical instrument to "A" [not true for all instruments] BIG musical production [grand finale] -- Post-Movie Demos: 1. Logger Pro plus "Ultimate Blues Machine" one-string guitar (100 samples/min. for 10 min.): string vibrates, causing air to vibrate, etc. Microphone converts pressure to voltage. "Sound graph" shows change in voltage as a function of time: crests = compressions; troughs = rarefactions. 2. "Audacity" demos using sound files: 10-sec_middle-C.wav; 07-sec_eight-notes.wav; 211_planearium.wav. Points-of-focus: A) change in volume = change in amplitude; B) change in pitch = change in frequency. The freeware audio editor called "Audacity" is available from: http://audacity.sourceforge.net/ Generating the audio is trivial; once you have the application open, just choose "Generate | Tone" and follow the prompts [amplitude = 0.50]. Export as WAV file. Click on "Zoom Tool" in order to see sine wave. Ctrl-A = select all Effect: Fade Out; Fade In; Cross Fade In Q. ...how to smoothly edit a word out of an "Audacity" recording? I would like to showcase some of Audacity's sound editing capabilities during my demos in class Thursday. I would like to do the speaker/microphone demo, then edit the recording: First I'll say, "I am not a smart man, Ginny." (Forrest Gump); then I'll edit out "not." Kids will think that's cool. Can you tell me how to make the edit? I vaguely remember you telling me about a trick to make the cut/paste w/o a popping noise -- something about getting the segments to line up smoothly along the rest position (equilibrium). WBS A. Highlight the region in question. Hit "Z" key to move the selection endpoints to zero crossings (you won't really see anything happen when you do this). Then Edit | Cut or just hit Delete to remove the segment. PSW Note: [see menu bar] Look on [at] the Edit menu -- "Find Zero Crossings" -- you'll see that the "Z" key is the shortcut. Highlight a region and then hit the space bar; that will play just what's highlighted. Also, enunciate carefully when you record. It's amazing the degree to which sounds overlap in normal conversational speech. If you speak a bit more deliberately, you'll get some gaps that may be easier to work with. PSW Forrest Gump: "I am not a smart man, Jenny." [edited version] "I am a smart man, Jenny." [cut "not"] "I am not a man, Jenny." [cut "smart"] == Range of human hearing: 20 - 20,000 Hz [24MAR2008] Range of human hearing: 20- to 20,000 Hz My hearing range: =110 Hz practically inaudible to me [may be more a result of the laptop speaker quality than poor hearing (ref. PSW)] >15K - can't hear =12.5K barely audible =10.0K is audible, but ear-piercing! -- Subject: Sound Recording: Longitudinal- to Transverse Wave Conversion microphones convert pressure waves (sound) to voltage output of a microphone is voltage [sidebar] capacitor: two plates w. (nylon) insulator in between diaphram = flat condenser plate connect rod to diaphragm; add pen to rod. rod will trace sine wave on scrolling piece of paper! http://www.wsanford.com/~wsanford/gr8ps/03_purple/08_sounds_cool/extras/ eight-notes.wav (0:07 sec.) http://en.wikipedia.org/wiki/Piano_key_frequencies ~262 Hz (C4, middle C) - ~523 Hz (C5) Rule of Thumb: sample at 2x max. frequency, e.g., 1200 samples/second Using Logger Pro: Experiment/Data Collection.../ Length: 7 seconds Sampling Rate: 1200 samples/second practical application: Audio CDs 44,100 Hz = ~2x max. human hearing 44.1 KHz = ~2x max. human hearing == DEMOS ----- > "speaker/microphone" - make connection with "motor/generator" (see related notes, 03_the_big_switch/00_readme.txt) > "Kustom" police radar/lidar guns [Officer Marvin Goodley] http://www.kustomsignals.com/index.asp > Sound Waves (slinky) http://www.exploratorium.edu/snacks/slinkyinhand/index.html > "Beaker Xylophone" How do you tune a fish (tuna fish)? With the fish (its) scales, of course! Use labeled beakers; tune a "major scale" as follows: LOW-C - 1042 ml (IMO, slightly <990 ml sounds better) D - ~585 ml E - ~510 ml F - 580 ml G - ~410-412 ml A - 310-312 ml B - 295 ml high-c - ~180 ml Twinkle, twinkle, little star: cc gg aa g | ff ee dd c | gg ff ee d | gg ff ee d | cc gg aa g | ff ee dd c Star Wars theme song: C G | F E D high-c G | F E D high-c G | F E F D > Sound tube (Bernoulli Principle, or not) http://www.stevespanglerscience.com/product/1192 Materials: The "Singing Tube" is a popular and inexpensive item in toy stores. There is really nothing to it - a corrugated plastic tube measuring about 3 feet long and 2 inches in diameter. (debunking BP) http://isaac.exploratorium.edu/~pauld/activities/AAAS/aaas2001.html CAN SCREAMER http://www.darylscience.com/Demos/CanScreamer.html == Google Search: physics of sound The Wave Theory of Sound http://www.cartage.org.lb/en/themes/sciences/Physics/Acoustics/history/ TheorySound/Theorysound.htm Acoustics is the science of sound, including its production, transmission, and effects. ... disturbances with frequencies too low (infrasound) or too high (ultrasound) to be heard by a normal person are also regarded as sound. One may speak of underwater sound, sound in solids, or structure-borne sound. Acoustics is distinguished from optics in that sound is a mechanical, rather than an electromagnetic, wave motion. -- The Physics Classroom - a high school physics tutorial Sound Waves and Music http://www.physicsclassroom.com/Class/sound/soundtoc.html Lesson 1-5 -- Physics Demonstrations - Sound http://sprott.physics.wisc.edu/demobook/chapter3.htm (incl. list of, "Table 3.2 The Notes of the Even-tempered Scale for the Octave Above Middle C(a)") -- Piano key frequencies http://en.wikipedia.org/wiki/Piano_key_frequencies