Assignment 5 Audio & Files in MATLAB Due Friday, November 16, 11:59 pm

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1 Assignment 5 Audio & Files in MATLAB Due Friday, November 16, 11:59 pm Remember to comment your.m files using % or Matlab Text Comment. help and doc is your friend. Submit the indicated files via to matlabfunucsd@gmail.com: Part 1 (5 points): o LastName_Birthday.m o LastName_CreateSong.m o LastName_HappyBirthday.wav Part 2 (5 points): o YourLastName_CollectData.m o YourLastName_MainExp.m o YourLastName_Analysisfile.txt o At least 3 text datafiles, one for each subject (examples below): YourLastName_datafile_ABC.txt YourLastName_datafile_DEF.txt YourLastName_datafile_GHI.txt Extra Credit (optional; 1 point) o YourLastName_Images.m o YourLastName_EC_Myimg2.jpg For this assignment, you will be submitting six main files (three for Part 1, three for Part 2) and at least three additional text files for Part 2. If you attempt the extra credit, you will submit 2 more files. Make sure you attach all of them (you may want to zip them, but if you do this, please check that your zip file contains all the files)! In filenames, YourLastName should be replaced by your actual last name. Please read the instructions carefully. Everything you need to complete the homework is specified. If you are uncertain about something, read the instructions again. If you are still unsure, ask for clarification.

2 Part 1. Audio in MATLAB (5 points) You will write a program that will play and save the song Happy Birthday to You. Read through this entire section before starting. There is a Music Theory Crash Course at the end to help you. Part 2 File Diagram This program will contain a main script called LastName_Birthday.m and a function called LastName_CreateSong.m that will take in a list of notes and create an audio array. When complete, submit LastName_Birthday.m, LastName_CreateSong.m and the file LastName_HappyBirthday.wav that you will create. Hint: Much of Part I is similar to the example PlayNotes.m. It will be helpful to regularly reference that script. LastName_Birthday.m 1. Define the variables: a. fs: the sampling rate (when running it, use 44000Hz as fs) b. melody: an array representing the notes in the song Happy Birthday to You. 2. Call the function LastName_CreateSong with melody and fs as inputs. LastName_CreateSong, described in further detail below, should take two inputs corresponding to the melody and sampling rate (fs) and have one output, corresponding to the song, as an array. 3. Using the outputs of LastName_CreateSong function, should play the song through the speakers or headphones, and then save the song as a.wav file called LastName_HappyBirthday.wav (hint: help audiowrite). LastName_CreateSong.m

3 1. Input: a list of note degrees, melody, and a sampling rate, fs. 2. Output: an array, songaudio, a numeric vector that contains an audio version of the song represented by melody. 3. Specifications: Convert every note degree in melody to a frequency, then produce a sound wave containing a pure tone played at each of that frequency for 0.5 seconds with a silent gap of 0.1 seconds after each tone. For all audio, we should use a sampling rate of 44,000Hz. Those waves should all be concatenated into a single array called songaudio so they form a single audio file. The complete audio array songaudio is the output of LastName_CreateSong.m. To complete the second part of this function, you will have to use the equation mentioned below (also in PlayNotes.m) for calculating the frequencies of each note. Then, to create a sound wave for one note, you will use the frequency you just calculated, the duration of the note to be played (0.5 seconds) and the sampling rate fs. To create silence at the end of each note, you will need the sampling rate fs and the length of the silent gaps (0.1 seconds). - Hint: remember silence is represented by 0s. You should then combine the sound waves for each note, with silences, to create a new array called songaudio. - Hint: remember that you can concatenate any number of arrays with square brackets, eg. [x y]). Music Theory Crash Course

4 Happy Birthday to You in the key of G has the following notes (spaces are just to help you visualize things. For HW 5, we can assume all notes are the same duration): G G A G C B G G A G D C G G G2 E C B A F F E C D C To compute the frequencies of these notes later, you can represent the notes by their degree or what order they are in a chromatic scale, starting at the root note of the key (here: G). If you use the above image as a reference, you can convert the notes to numbers like below: melody = [ ] Remember that the ratio of the frequency any note to its octave is always 1:2. So, the frequency of the G indicated by 12 above is exactly twice that of the G indicated by 0. G0 above is generally played at Hz, so G12 is ( * 2 1 ). We can extend that calculation to any note above by looking using the equation below: freq(note) = RootFreq 2 Degree(Note)/12 So, for instance, a B in the key of G has a degree of 4, so its frequency is * 2 (4/12). (Hint: The above equation is implemented in PlayNotes.m. The array whitekeys is the equivalent of melody here.)

5 Part 2. Writing to Files (5 points) You will modify your solution for HW4 to add the output to text files for each subject in addition to saving mat files, plus write an analysis file of all subjects. There is a diagram at the end that may be helpful. Recall the two functions you wrote for HW4, YourLastName_MainExp.m and YourLastName_CollectData.m. Each should be modified to write text files in addition to what they already did (refer to HW4 for details) as follows. Part 1 File Diagram YourLastName_CollectData.m The new function YourLastName_CollectData.m should be the same as HW 4 in its inputs, outputs and what it does, but extended such that it also writes each trial of the data in a tab-delimited text file named YourLastName_datafile_<Subject Initials>.txt (e.g., YourLastName_datafile_APS.txt). You should write to the text file after each trial, not at the end of running all trials. Your text file should look something like the box on the left below (though the Number and RT of each trials will of course differ). YourLastName_CollectData.m should create a new data file for each subject, based on the initials it takes as input.

6 Data File Subject Initials: APS Accuracy Analysis 3 subjects data were analyzed Test Time: 27-Feb :39:21 Subject APS: 0.95 TrialNo Number RT Subject SPM: 0.75 Subject FL: Should be one data file per subject! Should be just one analysis file total! YourLastName_MainExp.m YourLastName_MainExp.m should also perform similarly to HW4. It does not return an output. You should modify YourLastName_MainExp.m such that it writes an analysis of collected data into a text file called YourLastName_Analysisfile.txt. Note that there are individual data files for each subject for data collection, but there is a single analysis file created for the whole experiment in YourLastName_MainExp.m. The function should write into the text file YourLastName_Analysisfile.txt some text as shown in the example in the box on the right (again with your own data, so the initials and numbers will be different). The information in the file should be as shown in the example, including how many subjects data were analyzed (depending on how many initials were received in the input cell array). For each subject, the function should calculate the mean accuracy for all trials and write on a separate line in the text file. You should write the data for each subject as they are run, not all at once at the end (this should make it easier as you won t need any additional loops). Once everything is ready, run the main experiment with an input cell array of initials of your choice, that should contain at least 3 subjects. Submit YourLastName_CollectData.m and YourLastName_MainExp.m, as well as all the text files created (i.e. 3 or more subject data files (e.g. YourLastName_datafile_ABC.txt) and the analysis file YourLastName_Analysisfile.txt).

7 Extra Credit: More Practice with Images (1 point) Save the commands you used to achieve the below in a script called YourLastName_Images.m. 1. Download good_puppers.jpg to your computer. 2. Read in the image as a variable Myimg and display in a figure window using imread. Your Task Check out the dimensions and values in Myimg. Create a new, cropped image Myimg2 that displays the middle dog in Myimg vertically. You will need to play around a little to find the indices that will give you the middle dog. Your new image should therefore differ only in the number of elements in the second dimension). If you view Myimg2 in the figure window (axis image and axis off), it should look something like this: The image does not have to be exactly as above. As long as the second dog is almost completely visible and not much of the other dogs are in the image, it s OK! Save the image (from the figure window or using the function saveas) as YourLastName_EC_Myimg2.jpg. You will submit two files. Save the commands you used to achieve the above in a script called YourLastName_Images.m, and submit this along with YourLastName_EC_Myimg2.jpg.