Talk:Microphone

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Revision as of 18:43, 29 September 2009

We received your report, and we have some comments and questions. It sounds like you have identified a few opportunities for improvement including noise reduction, sensitivity / efficiency improvements. Please respond point by point to the items below. We are looking forward to seeing your ideas in Report 2.

• Executive Summary: Clear coverage of findings in each area. Would be better if shorter (~50%) and more concise covering only most interesting or nonobvious findings (e.g.: don't need to tell client that manufacturer and retailer are important stakeholders to consider, but if there are important needs specific to the design of the product, could mention those).
• Stakeholder Needs: Good list of needs. Some appear to be missing such as durability, ability to turn on/off, avoidance of background noise and feedback, quick to adjust, etc.
• Use: Good description. How long does it typically take for a user to set up the microphone, and how long does it take to adjust all of the degrees of freedom to get the microphone into a comfortable position?
• Assembly: Nice clear labeled image of stand and mic.
• Mechanical Function: Clear explanation. For mic it is described that the diaphragm "causes air molecules underneath it to vibrate. These in turn push down on the magnet that is surrounded by coils of wire." Is it really true that the diaphragm is not physically connected to the coil of the magnet? If so, how is the magnet suspended? Isn't the mass of the magnet too great to respond to high frequency air vibration? Your diagram seems to show a coil attached to the diaphragm that moves past a stationary magnet. Please revisit this and provide an updated explanation with picture or diagram if necessary.
• Mechanical Analysis: The client does not read MATLAB code so please include your equations using standard mathematical notation, defining your specific notation. If you want to include code it should be standard pseudo-code (although MATLAB-specific code could also be included with the pseudo-code). Any MATLAB functions that represent some more complicated numerical method should be briefly explained instead of just mentioned. Formatting your lists as lists instead of as paragraphs would make the report easier to read.
  • You seem to say in different places that the number of coils is either 50 or 10, so please clarify.
  • What do you mean when you say that formula used to find generated emf was "crude"?
  • How do you set SPL = 0.6Pa, b=2e-5 for air? Cite sources.
  • How do you know k = 50 N/m for this diaphragm? Is it linear? Is it consistent with material and geometry assumptions?
  • It appears G is a function that is zero for all t except t=1, so this is an impulse with a length of time = 0. Matlab will not be able to resolve this and will likely approximate it as an impulse with a time length equal to deltaX, the step size of the simulation. Thus your input depends on the simulation parameters - not good. Should define a well-defined input pulse to get a meaningful response.
  • Why not examine a Bode plot instead? More revealing of response characteristics.
  • The two graphs provided do not have axes labeled or time steps specified - difficult to interpret. Table is not clear.
• Bill of Materials: Good list. Why is casting and machining listed for one of the plastic parts? Please clarify.
• DFMA: Good observations about material and manufacturing choices. Do you have any comments on DFMA guidelines that were or could have been followed?
• FMEA: Your FMEA conclusions seem to contradict the failure you observed with the soldering. Please reconcile.
• DFE: If a CO2 tax were passed, causing electricity prices to increase, presumably these cost increases would be passed to the industries purchasing electricity, so expenses associated with the full carbon emissions in the supply chain would be relevant to the product. Please give us an estimate of how much this might add to the life cost of the product. You also did not comment on emissions associated with production vs. use.
• If any of your images, figures, or text were taken from another source, please be certain to provide proper attribution.