Mini Project – Audio Enhancement

Author: University of HertfordshireDate created:Date revised: 2009

AbstractThe following resources come from the 2009/10 BSc (Hons) in Music Technology (course number 2ELE0077) from the University of Hertfordshire. All the mini projects are designed as level two modules of the undergraduate programmes.

Project Objectives: The objectives of this module are to demonstrate within the MATLAB® Simulink® environment:

an understanding of the use of digital filtering for processing audio signals the knowledge and ability to introduce echoes into digital speech/music to develop a working knowledge of the mathematical theory introducing artificial reverberation into

audio signals.

ContentsSection 1. Project Introduction.......................................................................................................................... 2Section 2. Project Specification........................................................................................................................ 3Credits.............................................................................................................................................................. 5

In addition to the resources found below there are supporting documents which should be used in combination with this resource. Please see:Mini Projects - Introductory presentation. Mini Projects - E-Log.Mini Projects - Staff & Student Guide.Mini Projects - Standard Grading Criteria.Mini Projects - Reflection.

You will also need the ‘Mini Projects – Audio Enhancement’ presentation.

© University of Hertfordshire 2009 This work is licensed under a Creative Commons Attribution 2.0

License.

Mini Project- Audio Enhancement

Section 1. Project Introduction

Project Title: Audio Enhancement

Project Objectives: Demonstrate within the MATLAB® Simulink® environment:

an understanding of the use of digital filtering for processing audio signals the knowledge and ability to introduce echoes into digital speech/music to develop a working knowledge of the mathematical theory introducing artificial reverberation into

audio signals.

Project Summary: (50 words max)An important aspect of audio processing is to enhance the quality of audio (music) recording through the introduction of artificial reverberation. The natural occurrence of reverberation in audio is due to a mixture of sound delays and reflections from different surfaces in the operating environment. When music is played in a closed environment (e.g. a hall), the sound reaches any given listener in the environment from various angles (with different levels of delay). Using digital signal processing, it is possible to artificially generate the effects of such multiple reflections of sound and thereby enhance the quality of a recorded audio. This is the basis of this project in which the students are required to develop systems for generating artificial echoes and reverberations for given audio files.

Introductory Lecture (2hrs) Content:Principles of the relevant aspects of digital signal processing (DSP).

DSP elements Basic principles of discrete-time signals Introduction to digital filtering

Introduction to audio reverberation Introduction to reverberation in closed space environments Introduction to DSP tools for generating artificial reverberation

Preparation Session (3hrs):Introduction to the use of Matlab® Simulink® for audio signal processing:

i. Signal capture and playback, ii. Digital filtering, iii. Simulink®-based system design

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Mini Project- Audio Enhancement

Section 2. Project Specification

1. Learning Outcomes assessed (as taken from the DMD)

All Learning Outcomes specified in the Definitive Module Documentation are assessed as part of this mini project, the specific Learning Outcomes are:

Knowledge and Understanding Be able to analyse and breakdown problem tasks into manageable steps. Integrate previous and concurrent learning and to use it to solve technology-based problems. Be able to describe the project life-cycle appropriately. Be able to select appropriate Music Technology and techniques for a given situation.

Skills and Attributes Produce a solution to a defined Music Technology problem. Carry out a simple critical evaluation of their solution. Demonstrate an ability to work effectively in a team, small groups and individually. Demonstrate an ability to manage time and resources effectively.

2. Project Title: Audio Enhancement

3. Project Objectives: (technical, specific to this project)Demonstrate within the MATLAB® Simulink® environment:

an understanding of the use of digital filtering for processing audio signals the knowledge and ability to introduce echoes into digital speech/music to develop a working knowledge of the mathematical theory introducing artificial reverberation into

audio signals.

4. Project Summary: (50 words max)An important aspect of audio processing is to enhance the quality of audio (music) recording through the introduction of artificial reverberation. The natural occurrence of reverberation in audio is due to a mixture of sound delays and reflections from different surfaces in the operating environment. When music is played in a closed environment (e.g. a hall), the sound reaches any given listener in the environment from various angles (with different levels of delay). Using digital signal processing, it is possible to artificially generate the effects of such multiple reflections of sound and thereby enhance the quality of a recorded audio. This is the basis of this project in which the students are required to develop systems for generating artificial echoes and reverberations for given audio files.

5. Introductory Lecture (2hrs) Content:Principles of the relevant aspects of digital signal processing (DSP).

DSP elements Basic principles of discrete-time signals Introduction to digital filtering

Introduction to audio reverberation Introduction to reverberation in closed space environments Introduction to DSP tools for generating artificial reverberation

6. Preparation Session (3hrs):Introduction to the use of Matlab® Simulink® for audio signal processing:

iv. Signal capture and playback, v. Digital filtering, vi. Simulink®-based system design

7. Day 1

Expected Outcomes for the day:Students working individually must carry out a series of tasks concerned with digital processing of audio signals based on Matlab® Simulink®. The main aspects of these tasks are inputting and outputting audio signals, digital filtering and introducing delays and echoes into audio signals provided. A briefing pack which contains instructions and the required audio signals will be provided at the start of the day. Assessment criteria; successful implementation of the individual parts of the exercise, testing and demonstrating the operation in each part, defining the system parameters according to the processing requirements.

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Mini Project- Audio Enhancement

Key Tasks:Basic delays, echoes and digital filtering

Capturing, playing back, and storing speech and music using Matlab® Simulink®. Developing a system for introducing artificial echoes into short audio signals. Analysis of the effects of variations in sampling frequency on a DSP-based echo generator. Development of basic digital filters for processing audio signals.

8. Day 2

Expected Outcomes for the day:Students working individually must develop a complete DSP-based, audio reverberation system according to the prescribed specifications. The performance of the final system must be subjectively tested and demonstrated. A briefing pack containing the required audio signal and information about the reverberation specification and system structure will be provided at the start of the day.

Assessment criteria: The effective management of the project, understanding of the audio reverberation characteristics, ability to determine the reverberation system parameters based on the information provided, structuring and implementing the system using Matlab® Simulink®, testing and demonstrating the system operation.

Key Tasks:Detailed artificial reverberation based on Matlab® Simulink®

Analysing the required reverberation characteristics. Determining the structure the DSP (digital signal processing) reverberation systems. Development of a complete experimental system for introducing artificial reverberations into audio. subjective testing of the system developed.

9. Facilitator guidance (key ideas to draw out from students):Day 1: the use of Simulink® for audio capture, playback and simple audio manipulation; completion of a simple (working) echo generator; completion of simple (working) digital filtering of audio. Day 2: the processing methods used for the generation of complex artificial reverberation in audio; determination of the system parameters and the Implementation of the complete reverberation unit; experimental testing at different stages using the audio signals provided.

10. Required Resources: Laboratory Facilities and Teaching Support.Laboratory Resources: D401

1. PC Workstations with Matlab® Simulink®, audio editing using Adobe Audition.

2. headphones.

Teaching Resources:

3. Preparatory Session; D401: structured workshop based on a set of Matlab®-based exercises.

4. Day 1: briefing pack containing instructions for the day and audio material.

5. Day 2: briefing pack containing instructions for the day and audio material.

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Mini Project- Audio Enhancement

CreditsThis resource was created by the University of Hertfordshire and released as an open educational resource through the Open Engineering Resources project of the HE Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.

© University of Hertfordshire 2009

This work is licensed under a Creative Commons Attribution 2.0 License.

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