11/28 Observe the demonstration and complete the following:

• Write a statement explaining how you think the snare drum is being “activated”

• Did you use the word “energy” in your answer?

• “An object at rest stays at rest unless acted on by an outside force” – Newton’s First Law of Motion

Will a barrier affect the drum noise?

– Distance – Frequency– Volume– Directionality of the source– “Focusing” the sound like using a megaphone

What are some other factors may change the level of vibration in the drum?

• Sound is produced when air is disturbed in some way.

• Sound travels as a compression, or longitudinal, wave.

• http://www.gmi.edu/~drussell/Demos/waves/wavemotion.html

• Vibrations carry energy. Ocean waves are another kind of vibration that carries energy.

• Sound energy can be absorbed or reflected.

–Reflected by solid, flat surfaced

–Absorbed by soft, porous materials

• Vibrations in materials set up wavelike disturbances that spread away from the source

Light and Sound Similarities

• Something can be "seen" when light waves emitted or reflected by it enter the eye.

• Something can be "heard" when sound waves from it enter the ear.

• The snare drum models the way an eardrum senses sound waves.

Active vs. Passive Systems

• The effect of sound waves can be reduced through active and passive means.

• Passive – sound barriers and insulation systems can block and absorb noise

• Active – electronic and mechanical devices “tuned” to produce sounds that interfere with noise.

Interference

• The interaction between two or more simultaneous waves is called interference

Constructive Interference

Interference

• The interaction between two or more simultaneous waves is called interference

Destructive Interference

Interference• Sines A and B have different frequencies. That

means that their phase relationship constantly shifts with time: at one moment they are in phase and at another moment they are out of phase.

Hearing “Beats”

Solving the “noise” problem

• What are some sources of “noise pollution”?– Traffic (also bad mufflers, loud car stereos…)– Air conditioners and fans– Construction– Water pumps for pools

• Some technological problems are best solved through experimentation.

– Remember that Edison tried over 1000 filaments?

• Invention is a process of turning ideas and imagination into devices and systems.

• Innovation is the process of modifying an existing product or system to improve it.

• A decibel (dB) is a measure of sound intensity. The dB scale is logarithmic, meaning that a change of 10 dB represents a tenfold change in loudness. So, a sound measuring 30 dB is 10 times louder than a sound measuring 20 dB.

• Sound Level Meters are used to measure dB level.

• Locations of sensing devices will affect the levels observed.

5/10 Answer in a complete sentence.• Watch the 4 minute video clip.

• Write a statement describing how frequency affects the travel of sound over long distances.

12/5 Answer in a complete sentence.

• What strategies (reflection, absorption, or diffusion) is your group using in your noise reduction panel?

12/8 Answer in a sentence

• If we were to place you panel on the box backwards how do you think its performance would change?

• Why do you think this?

5/12 Answer in a sentence

• Identify a practical application for your noise reduction panel.

–Where might it be used?

–Who would use it?

12/6

• Watch the short video and record information about the speed of sound.

• Sound energy can be reflected, absorbed, diffused – sketch each

Drill 11/30

12/1 Copy

• The parameters placed on the development of a system are called requirements.

• Requirements are made up of criteria and constraints