During the 6th week of the engineering design project the design team worked on constructing the speaker cabinets, deciding how to collect data from the speakers, and getting preliminary data of the speaker without the enclousure.  The picture below shows the constructed speaker cabinets.

One design change that came up during the construction was to make the baffle, which is the face of the cabinet that the speaker is mounted to, out of plywood.  This decision was made for several reasons.  The first was that the oak cabinet would have gone over the allotted 30 dollars for materials if another piece of it was used, and the plywood was cheaper.  Also, MDF and Oak wood split very easily.  With the mounting screws so close to the edge of the hole drilled for the speaker, something that wouldn't split as easily was needed for the construction.

Another task that was accomplish was to decide which tests will be done on the speakers and how data would be collected.  The three tests that will be done on the speakers are a frequency response test, vibration test, and a subjective test on sound quality.  The frequency response test will be done with an iPhone application.  This application allows the user to play different frequencies and use the microphone on the iPhone to record the volume of sound produced by the speakers.  The application does not give a unit for the measurement of volume, but since the measurements are being used for comparisons, this will not cause a problem.  This will be done 3 in. from the speaker and 7 in. from the speaker.  This will allow the design group to see how the material in the cabinet alters the sound produced by the speaker.  The vibration test will also be done with an iPhone application.  This application uses the accelerometers in the phone to record the acceleration in the X,Y,and Z direction over a period of time.  The frequencies will be selected in the high, middle, and low range to test the vibration of the cabinet.  Since vibration of the cabinet can produce it's own sound, this test will allow the team to see which cabinet does this the least.  Finally,the design team will use test subjects (people) and play a track through one speaker, then the other and have them decide which speaker they like better.  This is a subjective test because different people can have different perspectives on what sounds better when it comes to music.

The final task that was completed was a frequency response test for the speaker without an enclosure. This test will hopefully help see what differences the enclosure makes, not just compared to another cabinet, but in general.  As seen in the graphs below, which are graphs of the volume of sound produced by the speakers at different frequencies, speakers that do not have enclosures have bad frequency responses.  The optimal response is a flat line. This flat line means that the speaker produces every frequency at the same volume.

This is mostly due to the standing waves produced by the back of the speaker.  As explained before, these standing waves can cancel out the waves produced by the front of the cone of the speaker, altering the frequency response.  The hope of the design team is that the cabinet will reduce these standing waves and level out the graph.