# Department of Linguistics

## SPEECH ACOUSTICS

## Basic Acoustics

This topic consists of four documents:-

### 1. What is Sound?

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### 2. Basic Acoustics Course Notes

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These notes cover some essential concepts in basic acoustics. You should read these notes carefully and make sure that you understand both the concepts and the accompanying maths. The maths in this topic is the only maths that you will be required to master for this subject.

- Some Notes on Terminology
- Acoustic Units of Measurement
- Wavelength, Period, Frequency and the Speed of Sound
- Sound "Amplitude"
- deciBels (dB)
- Adding or Subtracting two dB or Sound Pressure Values
- Root Mean Squared (RMS) Average of Sound Pressure
- Acoustic Intensity and the Inverse Square Law
- The Doppler Effect

### 3. Basic Acoustics Appendix

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These notes provide additional detail on the topics covered in the first set of notes. You will not be assessed on this material but it is desirable that you are at least familiar with it.

- Appendix 1: Scientific Notation
- Appendix 2: Logarithms
- Appendix 3: Basic Physical Units of Measurement
- Appendix 4: Acoustic Units of Measurement
- Appendix 5: Some Extra Notes on deciBels
- Appendix 6: The Velocity of Sound
- Appendix 7: Acoustic Intensity and the Inverse Square Law

### 4. Basic Acoustics Practice Questions

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These notes consist of 28 sample questions and their answers. You should try them all between weeks 1 and 2. The Basic Acoustics Course Notes contain explanations on how to do most of these questions. Some questions similar to these will form part of the first class test.