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Unformatted text preview: E85.1801 Fundamentals of Music Technology Fall 2009 Instructor: Juan P. Bello Assignment # 02 Intensity vs. Distance Full Name:____________________________ Email:_________________________ Description: For this assignment you are expected to perform a set of small experiments as explained below. Please record the results of the experiments on a short report (max. 4 pages) that also: (i) discusses the reasons for the results you have got, (ii) describes any difficulties that you had during the set‐up of the experiments and (iii) provides answers to the questions below. While the experiments should be done in small groups of 2 or 3 people at a time (as long as everyone participates), the reports must be individually written. Instructions: • The experiments on this assignment can be performed in studios E or F (see 8th floor support desk for studio booking schedules). • For the experiments you will need to borrow the following from the support desk: 1. JBL Eon powered Speaker and Power Cord 2. 1/8” mini to XLR Male adaptor (you may have to ask twice to get this right) 3. 10’ XLR cable. 4. Radioshack Sound Pressure Level (SPL) Meter 5. One person in the group will need to bring a laptop to run the provided signal generating software. • Connect the 1/8” mini plug to your computer (via the headphone output) connect the XLR male end to the XLR cable, connect the cable to the input of the JBL Eon. Connect power to the JBL Eon, turn any and all volume controls to the minimum setting, and switch on the JBL Eon. • Start the Software on the computer (follow instructions contained within the program). Slowly turn up the volume on the JBL until you get a reading on the SPL meter (with the meter set to 80db, A‐weighted, slow response). • At the end of the experiments please return all equipment and leave the studio in at least as good condition as you found it. Experiments: 1. Once you have established that the sound is completing the circuit from the software to the speaker, use the meter to measure the sound level at approximately 3 and 6 feet in front of the speaker. Hold the meters very still or place it on a music stand to avoid adding handling noise to your readings. 2. Plot these measurements on a graph of dB over distance. Questions: How did the dB SPL change with distance if at all? What is the expected change in intensity? What noise sources were present, if any, that may have skewed your results? Where was the speaker placed in the room? Specifically what distance was the speaker from the walls, floor and ceiling? What direction was the speaker facing? Other than distance, where was the SPL Meter relative to the speaker? Report: Answer the above questions as complete thoughts in formal English. Analyze and discuss the results of the experiments, trying always to relate your findings and observations to the theory discussed in class and the demo sessions. ...
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- Fall '09