Docsity
Log inSign up
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search Store documents

The best documents sold by students who completed their studies

Search through all study resources
Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

University Rankings

Discover the best universities in your country according to Docsity users

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

From our blog

Exams and Study
Go to the blog

Signal Sampling - Elements of Discrete Signal Analysis - Laboratory Assignment, Exercises of Signal Processing and Analysis

Baba Ghulam Shah Badhshah UniversitySignal Processing and Analysis

The Elements of Discrete Signal Analysis and the interactive internet programming with java, is very helpful series of lecture slides, which made programming an easy task. The major points in these laboratory assignment are:Signal Sampling, Manipulation and Playback, Audio Properties, Matlab Built-In Functions, Constant Attenuation, Matlab Function File, Echo-Generation Process, Variety of Echoes, Plot Waveform, Audio Effects

Typology: Exercises

2012/2013

Uploaded on 04/24/2013

baijayanthi
baijayanthi 🇮🇳

4.5

(13)

171 documents

1 / 2

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Laboratory Assignment 2: Signal Sampling, Manipulation and Playback
Purpose
In this Lab, you will learn how to record sounds and save them in MATLAB. You will learn how to
perform mathematical modifications to digital audio signals in order to produce some interesting audio
effects.
Objectives
By the end of this laboratory assignment, you should be able to:
• Record sound in MATLAB
• Use some simple mathematical manipulations to alter audio properties
Reference
Review Topics:
• Mathematical representations of continuous- and discrete-time signals
• Mathematical operations on signals
• Representation of sinusoids at specified frequencies
1. Record and save a speech signal
• Record yourself saying “hello world.”
o Make sure the microphone is on.
o In the Matlab workspace window, type
fs = 10000; %this is the sampling frequency in Hz
speech = wavrecord(40000,fs); % You want 40000 samples. How long is that
o Hit enter and then record the sentence immediately
• Save the speech you just recorded
o wavwrite(speech,fs,'myspeech'); % creates a .wav file of the signal speech
2. Read and play the speech you just recorded
• [sp,fs] = wavread('filename'); % reads in a signal and the recording frequency, fs,
• soundsc(sp, fs) %plays the read signal at frequency, fs
• Try playing the signal at different frequencies such as fs/2 and 2fs (note what happens and
explain why)
3. Plot and observe your recorded voices
• Plot the Waveform
• plot(speech);
• On your own add a title, axes labels and grid to the plot
4. Some Audio Effects
Apply each of the following MATLAB functions to your speech file, ‘my speech’. Save the new signal
to a .wav file using 'wavwrite' and then play back the signal. Observe the effect of these digital
manipulations on the audio properties of the signal.
Docsity.com
pf2

Partial preview of the text

Download Signal Sampling - Elements of Discrete Signal Analysis - Laboratory Assignment and more Exercises Signal Processing and Analysis in PDF only on Docsity!

Laboratory Assignment 2: Signal Sampling, Manipulation and Playback

Purpose In this Lab, you will learn how to record sounds and save them in MATLAB. You will learn how to perform mathematical modifications to digital audio signals in order to produce some interesting audio effects.

Objectives By the end of this laboratory assignment, you should be able to:

  • Record sound in MATLAB
  • Use some simple mathematical manipulations to alter audio properties

Reference Review Topics:

  • Mathematical representations of continuous- and discrete-time signals
  • Mathematical operations on signals
  • Representation of sinusoids at specified frequencies 1. Record and save a speech signal
  • Record yourself saying “hello world.” o Make sure the microphone is on. o In the Matlab workspace window, type  fs = 10000; %this is the sampling frequency in Hz  speech = wavrecord(40000,fs); % You want 40000 samples. How long is that o Hit enter and then record the sentence immediately
  • Save the speech you just recorded o wavwrite(speech,fs,'myspeech'); % creates a .wav file of the signal speech 2. Read and play the speech you just recorded
  • [sp,fs] = wavread('filename'); % reads in a signal and the recording frequency, fs,
  • soundsc(sp, fs) %plays the read signal at frequency, fs
  • Try playing the signal at different frequencies such as fs/2 and 2fs (note what happens and explain why) 3. Plot and observe your recorded voices
  • Plot the Waveform
  • plot(speech);
  • On your own add a title, axes labels and grid to the plot 4. Some Audio Effects Apply each of the following MATLAB functions to your speech file, ‘my speech’. Save the new signal to a .wav file using 'wavwrite' and then play back the signal. Observe the effect of these digital manipulations on the audio properties of the signal.

Docsity.com

  1. The MATLAB function half created by you in the first laboratory.
  2. The MATLAB function double created by you in the first laboratory,
  3. The MATLAB built-in functions fliplr and flipud.

Document how the MATLAB functions you use change the properties of the original tone and speech signals. In each case, does the speech segment sound like it was produced by the same speaker as the original? Why and/or Why not.

5. Echo Effects 1. Develop a MATLAB function, ‘myEcho’ to generate an echo. The output of this function should be the echo signal and the signal that you hear. A simple analytical model of an echo se(t) of a signal s(t) is se(t) = α(t-T)s(t-T), where the α (t) function attenuates the volume over time and T is the time delay introduced by reflection. In this treatment, we will assume that 0 ≤ α(t) < 1 and T> 0. This implies that the echo's strength is weaker than the true signal and that the echo always arrives at a time later than the true signal (post-echo). The signal r(t) that you hear is formed by a simple addition of the original signal and its echo. 2. Use the MATLAB function file you created to create an echo signal using your original speech signal and a constant attenuation. You will need to create a signal that is a scaled version of the original and add it to the original with the desired offset in time. Experiment with different values for the time delay and attenuation. Listen to the resulting signals and note your observations. 1. Generate a 0.25-second echo effect. Let α=0.65. 2. Use a non-constant attenuation function, such as an exponential: α(t)= Ae-t/τ. Determine values of A and τ that make an interesting effect. 3. Use several different delays and amplitudes to get a variety of echoes. 4. Use an oscillatory attenuation function, such as α (t)=Acos(ωt). Try different values for ω.

Describe the impact that your choices of Time delay and attenuation α have on the

resulting synthesized echo. Be specific out changes in parameters and relative impact on sound. What happens if T changes during the echo-generation process?

Docsity.com