Projects for week 2 lab

Choose one of these projects, do it, and turn in your write-up by Friday. You may work in groups of up to four, but each of you must turn in a separate write-up. In most of these, you'll have to give some thought to the effect of background noise.

1. Take one speaker and a generator. Keeping the frequency constant, choose a wide range of values of amplitude from the generator. Keeping the sound level meter in one place, measure the sound level in decibels as a function of the generator's amplitude. Think about how to plot your data - is there some way to treat the data so that your graph is a straight line? When you do that, does your straight line have the right slope?

2. We've done homework problems in which we calculate the decibel level resulting from combining two sounds of   known decibel levels. Verify this. Probably you want to use two speakers, two generators (Can you use just one?), and the decibel meter. Do several cases, including at least one where the individual decibel levels are comparable and one in which they are grossly different.

3. If you're equidistant from two identical sound sources you expect constructive interference. How does the intensity of the sound compare with the intensity of sound from a single speaker? Verify this experimentally.

4. Using at least four subjects (people, that is), construct a curve of constant loudness, that is, determine the decibel level at which a sound of a particular frequency sounds just as loud as a 1000 Hz sound of, say, 60 dB. Do this for a very wide range of frequencies, and compare your result with the data in the textbook.

5. It shouldn't take long to check whether the relationship between decibel level and distance from a source is what you expect it to be.