AUDL 1001   Autumn 2011

Signals and Systems for Speech and Hearing

Speech, Hearing and Phonetic Sciences
Division of Psychology & Language Sciences, UCL
Chandler House
2 Wakefield Street
London WC1N 1PF

This unit will present the concepts of signals and systems analysis that play a role in hearing and speech science. Emphasis is on the conceptual underpinnings of the area, through a primarily graphical approach, as opposed to the ability to do explicit mathematical calculations. These concepts are essential for understanding of many areas in hearing and speech science, including the functioning of the auditory system, the acoustic structure of speech, and the operating principles of auditory prostheses, including cochlear implants. Topics will include: the notion of a signal & system; decibels; the frequency characterization of signals & systems (spectra and transfer functions); the temporal characterization of signals & systems (waveforms and impulse responses); signals through systems; digital signals & systems.
Course Structure: The course is run in the first term only, on Monday afternoons, starting on 3 October 2011.
There is no meeting on 7 November due to it being reading week.
Each three-hour session will start with a lecture, and will comprise a varying mix of lecture, demonstrations, lab sessions and tutorials.

Venue and scheduling: The lecture starts at 14:00 in Room G15 on the ground floor of Chandler House. Some of the teaching will also take place on other floors of the same building.

Stuart Rosen 020 7679 4077 course organiser & lecturer
Steve Nevard 020 7679 4014 experimental officer
Dave Cushing 020 7679 4016 laboratory technician
David Greenberg post-graduate teaching assistant

Required text: Rosen, S., and Howell, P. (2010). Signals and Systems for Speech and Hearing, 2nd edition: Emerald Press, London. Chapters 11-14 in this new edition are significantly different from the earlier one. The syllabus for this unit is based on this book, with exercises and assigned reading for you to complete in it. It is more or less essential for you to own your own copy, and will also prove useful in other parts of the BSc Audiology course.

Supplementary Reading
Speaks, C. E. (1999). Introduction to Sound. 3rd edition. Chapman and Hall. ISBN: 1565939794.
This book is very readable and is aimed at students with little background knowledge of mathematics and physics. Each concept is introduced in non-mathematical terms before the corresponding mathematics is introduced. The explanations of exponents, logarithms and decibels are particularly good but more advanced topics are covered very sketchily with, at least in the 2nd edition, some serious misconceptions. See here for a review.

Haughton, P.M. (2002). Acoustics For Audiologists. Academic Press. ISBN: 0123329221.
A book more grounded in physics, which could also be of help in aspects of Auditory Biophysics. Can be quite tough going, though.

Requisite background
We assume that you are already familiar with basic mathematical concepts like exponents, and the use of graphs. The booklet An Introduction to Acoustics with answers may also prove useful.

Assessment for BSc Audiology
4 problem sets (5% each), distributed throughout the 10 weeks (see below). These will mostly be marked during the teaching session at which they are handed in so you must be present to receive a grade!
3-hour written paper (80%) in the main exam period of Term III.
You must pass the final exam to pass the course.

Assessment for all the MSc courses
A weighted average of the 4 problem sets, distributed throughout the 10 weeks (see below), will form 10% of your grade. These will mostly be marked during the teaching session at which they are handed in so you must be present to receive a grade!
A 2-hour written paper (80%) in the main exam period of Term III, also covering aspects of auditory biophysics.

Some of the links below are to PDF files which can be viewed using the Adobe Acrobat Reader. If you don't have the Acrobat Reader got and follow the links to download the free software.

Week by Week

The reading and exercises assigned here are not to be handed in, but it is essential that you do them! Unless otherwise stated, all are to be found in Signals & Systems for Speech & Hearing. Aim to complete the assigned work by the week following the date the material is covered in lecture.

Week 1: Signals

Teaching Material: Exercises: Read Chapters 1-3 and do the following exercises:
  • Do this diagnostic worksheet and bring it next week to go over in the tutorial session.
  • Chapter 1: exercise 3
  • Chapter 2: exercises 2, 3 & 5.
  • Chapter 3: exercises 1, 3, 4, 10, 11.
  • In the booklet An Introduction to Acoustics, ensure you are familiar with the material covered in pp. 1-19.
Other useful resources:

Week 2: Introduction to LTI systems

Teaching Material: Exercises:
  • Read Chapter 4 and do the following exercises:
  • Ch 4, p 62: ex 2, 4-6 (no formula needed for ex 6) 
Answers to Exercises: Other useful resources:

Week 3: The 'big' idea & frequency responses

Teaching Material: Exercises:
  • Work through Chapters 5 & 6 (Don't worry too much about the phase response of systems, but you do need to understand the concept of a cascade and calculating the total response from the individual ones)
  • Do the following exercises:
    • Ch 5, p 69-70: ex 4, 5
    • Ch 6, pp 109-113: Exercises 1A, 1D, 1E. Do the conversion from dB into volts only for 1D.(You may find it helpful to use a spreadsheet to do the appropriate calculations.) 
    • Exercises 2, 3
    • Exercise 4. Note that the microphone itself has a flat frequency response, so that the total frequency response (microphone + probe) is that given in the top figure of p. 110. Don’t do any of the calculations concerning the phase response for this or exercise 7. 
    • Exercises 7 & 10
Answers to Exercises:

Week 4: Spectra

Teaching Material: Exercises:
  • Read Chapter 7: Do exercises 1, 3, 4, 7 and 10 (pp. 148-149).
Answers to Exercises: Other useful resources:

Week 5: Signals through systems

Teaching Material: Exercises:
  • Do the quiz on page 5 of the lab handout from last week (harmonic spectra). 'Ratio' refers simply to the specified level of Pa divided by 20 µPa. In section C, ensure you convert the levels to µPa before you do the division. Then, take the log base 10 of that ratio and multiply by 20 to get the level in dB SPL. Also, ignore the extra use of the word 'Ratio'. All you are really meant to do is calculate the level of the component in dB SPL!
  • Read Chapter  8: Do the following exercises (pp. 163-165): 
    • Exercise 1: It will probably be easier for you if you draw the input spectrum of the sawtooth first. 
    • Exercise 2. 
    • Exercise 3. Remember, all these measurements relate to a single LTI system.
    • Exercise 4
    • Exercise 6. Assume that the fundamental component in both the input and output spectra has a level of 1 V.

Answers to Exercises:

Other useful resources:

Week 6: Filter banks

Teaching Material: Exercises:
  • Skip Chapter 9 for now. Work through Chapter 10 (don't worry too much about the details concerning impulses and impulse responses - you will hear more about them later) and Chapter 11, pp. 203-211.

Week 7: The ear as a signal processor

Teaching Material: Exercises:
  • Read Chapter 12 and do Exercises 3, 5 and 6 at the end of the chapter (p 285). 
Other Material:

Week 8:  Impulse Responses

Teaching Material: Exercises:
  • Work through Chapter 9 and answer the questions at the end of the chapter. 

Week 9:  Spectrograms

Teaching Material: Exercises:
  • Read Chapter 11, at least up to page 242. You can read the rest of the chapter if you are interested in the time domain approach to making a spectrogram. Answer at the end of the chapter: Q 4: b, d, & g; Q 5

Week 10: Digital Signals & Systems

Teaching Material:
  • lecture slides
  • lab session: Complete the tutorial in ESYSTEM concerning digital systems (available from the 'Help' menu) - section 5, parts a-d
  • Read Chapter 14.
  • Do exercises 1, 2, 4 & 5 (p. 339)

Other links to material concerning relevant topics

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Assorted Course Links

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