Friday, February 15, 2013

Week 24a 2013

Feb. 11-15, 2013

We have finished up the web design unit in class so make sure to come in the mornings to finish building your website.  We will be putting them online end of this week or early next week, which is how I will grade them.
We took the final web design test on Wednesday and Thursday, so if you were absent or tardy please come in the mornings and make them up.

We started the sound recording unit in class on Wednesday and Thursday.  We discussed some physics principles behind sound and broke up into groups for the sound recording project.  Ask me what group you are in if you were absent.  Terms to be familiar with the physics behind sound:

1.Wavelength - the length of one cycle in a wave. Changing the wavelength changes the pitch.
2. Amplitude - the height of a wave.  Change the amplitude changes the volume.
3. Frequency- how many cycles/second.  The unit of measurement is Hz.  To determine the frequency of a wave take the length of time for one cycle, ie .002 seconds, and divide it by one cycle: 1/.002 = 500 Hz.  This means that there are 500 cycles per second.
4. Equal Loudness Principle: If the amplitude stays the same but we change the frequency, low and really high frequencies sound quieter than the mid-range frequencies.  Our ears perceive the frequencies to be different volumes even though the volume isn't changing.  The louder the frequencies are played at the more similar the volume will be on all the frequencies.
5. Decibles- we measure the loudness of sound by decibles, dB.  Key decible levels are:
     40dB- whisper
     60 dB- conversation
     70 dB - busy street
     80 dB- acoustic guitar 1" away
     90 dB- baby crying
     110 dB- Power tools
     130 dB- Rock Concert.
6.  Dynamic Range of Human Hearing: 0 dB-120dB (threshold of human hearing)- 140dB (threshold of pain).
7. Frequency range of human hearing: 20Hz-20,000Hz.  lowest and highest perceived pitch.
8. Temporary Threshold Shift (TTS)- when we are in loud environments our ears protect themselves by temporarily shutting down, so we can't hear as well.  After a couple of hours or days hearing returns to normal, unless the exposure was too long in which case hearing damage becomes permeant.
9. Earwax- our body's natural protection against loud sounds.

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