We wish to show that the difference in sound levels is about 3 dB. Discussion This means that the two sound intensity levels differ by 3. Check Your Understanding Part 1 Describe how amplitude is related to the loudness of a sound.
Solution Amplitude is directly proportional to the experience of loudness. Part 2 Identify common sounds at the levels of 10 dB, 50 dB, and dB. Solution 10 dB: Running fingers through your hair. Conceptual Questions Six members of a synchronized swim team wear earplugs to protect themselves against water pressure at depths, but they can still hear the music and perform the combinations in the water perfectly.
One day, they were asked to leave the pool so the dive team could practice a few dives, and they tried to practice on a mat, but seemed to have a lot more difficulty.
Why might this be? The current sound intensity level, even though the rail yard is blocks away, is 70 dB downtown. The mayor assures the public that there will be a difference of only 30 dB in sound in the downtown area.
Should the townspeople be concerned? The warning tag on a lawn mower states that it produces noise at a level of What is this in watts per meter squared? What is the intensity of the wave? What intensity level does the sound in the preceding problem correspond to?
What sound intensity level in dB is produced by earphones that create an intensity of 4. What is the intensity of this sound in watts per meter squared? If a large housefly 3. Ten cars in a circle at a boom box competition produce a dB sound intensity level at the center of the circle.
What is the average sound intensity level produced there by each stereo, assuming interference effects can be neglected? The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound intensity level goes up by What is the maximum gauge pressure in a dB sound? An 8-hour exposure to a sound intensity level of What energy in joules falls on a 0. What decibel increase does an ear trumpet produce if its sound gathering area is cm 2 and the area of the eardrum is 0.
It may even lead to heart attacks. Noise levels of 50 dB at night increase cortisol a stress hormone production which causes arteries to constrict and elevates blood pressure. Atmospheric absorption of sound varies with environmental conditions such as relative humidity, atmospheric pressure, temperature, and wind. A substantial change in atmospheric pressure, equivalent to thousands of feet of elevation gain, has a small influence on noise level for most sources, but substantially affects the received levels of those sounds.
More importantly, wind and temperature can significantly affect how sound waves travel. Wind may cause sounds to be louder downwind, since the molecules through which sound waves propagate are being moved downwind, instead of spreading out equally in all three dimensions.
Vertical temperature gradients can cause sound to either refract away from the ground when warm air near the ground is beneath cooler air above or towards the ground when cool air near the ground is trapped by a layer of warm air above, i.
Students analyze sound level data. Use the data provided with this unit plan or other sound data including where, when and the conditions recorded under, and typical sounds like birdsong. The students can take a sound meter to different areas around the school to collect data. Students should record the time and conditions at which they sampled the data.
Using reliable books, articles, and websites, students research how sounds affect people and the natural environment. They can examine both positive and negative effects of sounds of differing loudness, intensity, and duration. Students also investigate methods by which sound intensity can be reduced. Students go to the place where they will be examining the effects of sound, such as a nearby park. Students bring sound level meters preferably capable of measuring dBA to record sound intensities.
Students will listen and record all sounds heard over a 15 minute period. How is sound used to identify fish? Communications How is sound used to communicate underwater? How is sound used to transmit data underwater? Research Ocean Physics How is sound used to measure temperature in the ocean? How is sound used to measure global climate change?
How is sound used to measure currents in the ocean? How is sound used to measure waves in the surf zone? How is sound used to measure the upper ocean? How is sound used to help make long-term measurements of the ocean? How is sound used to explore for oil and gas? How is sound used to measure, detect, and track oil? How is sound used to study undersea earthquakes? How is sound used to study underwater volcanoes?
How is sound used to map the seafloor? How is sound used to research wind energy? Investigate Marine Animals How is sound used to study marine mammal distribution?
How is sound used to estimate marine mammal abundance? How is acoustics used to monitor Arctic marine mammals? How is sound used to protect marine mammals? How is sound used to study the distribution of marine fishes? Logarithmic intensity scales are also used to report on the perceived brightness of light the sensitivity of the eye is also logarithmic and for measuring the strength of earthquakes the Richter scale.
A Physics Narrative presents a storyline, showing a coherent path through a topic For 9 Resources. The range of sounds that humans are able to hear is impressively large, taking us from the loud roar of an aircraft as it Physics Narrative The bel was invented by telephone engineers, and is named after Alexander Graham Bell, inventor of the telephone.
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