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Unformatted text preview: GEORGIA INSTITUTE OF TECHNOLOGY SCHOOL of ELECTRICAL and COMPUTER ENGINEERING ECE 2025 Spring 2009 Lab #4: Synthesis of Sinusoidal SignalsSpeech Synthesis Date: 39 Feb-09 You should read the Pre-Lab section of the lab and do all the exercises in the Pre-Lab section before your assigned lab time. The Warm-up section of each lab must be completed during your assigned Lab time and the steps marked Instructor Verification must also be signed off during the lab time by one of the laboratory instructors. After completing the warm-up section, turn in the verification sheet to your TA. Formal Lab Report: It is only necessary to turn in Section 4 as the lab report for this lab. A formal lab report is requiredit will be worth 150 points. More information on the lab report format can be found on t-square under the INFO link. Please label the axes of your plots and include a title and Figure number for every plot. In order to reduce orphan plots , include each plot as a figure embedded within your report. This can be done easily with MATLABs notebook capability. Forgeries and plagiarism are a violation of the honor code and will be referred to the Dean of Students for disciplinary action. You are allowed to discuss lab exercises with other students and you are allowed to consult old lab reports, but you cannot give or receive written material or electronic files. Your submitted work should be original and it should be your own work. Two Weeks: The report will be due during the period 1723-Feb at the start of your lab. 1 Introduction This lab includes a project on speech synthesis with sinusoids. The speech synthesis will be done with sinusoidal waveforms of the form x.t/ D X k A k cos .! k t C k / (1) where each sinusoid will have short duration on the order of the pitch period of the speaker. One objective of this lab is to study how many sinusoids are needed to create sounds that are intelligible. A secondary objective of the lab is the challenge of putting together the short duration sinusoids without introducing artifacts at the transition times. Finally, much of the understanding needed for this lab involves the spectral representation of signalsa topic that underlies this entire course. 2 Pre-Lab In this lab, the periodic waveforms and speech signals will be created with the intention of playing them out through a speaker. Therefore, it is necessary to take into account the fact that a conversion is needed from the digital samples, which are numbers stored in the computer memory to the actual voltage waveform that will be amplified for the speakers. 2.1 D-to-A Conversion Most computers have a built-in analog-to-digital (A-to-D) converter and a digital-to-analog (D-to-A) con- verter (usually on the sound card). These hardware systems are physical realizations of the idealized con- cepts of C-to-D and D-to-C converters respectively, but for purposes of this lab we will assume that the hardware A/D and D/A are perfect realizations....
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- Spring '09