A Study of French Horn

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  • A STUDY OF FRENCH HORN HARMONICS PAGE 1 OF 78

    DIPLOMA IN ACOUSTICS

    AND NOISE CONTROL

    A Study of French Horn Harmonics

    Andy Thompson

    Submitted for the Institute of Acoustics

    Diploma in Acoustics and Noise Control 2010

  • A STUDY OF FRENCH HORN HARMONICS PAGE 2 OF 78

    Q: How do you make a trombone sound like a French horn?

    A: Put your hand in the bell and play all the wrong notes.

  • A STUDY OF FRENCH HORN HARMONICS PAGE 3 OF 78

    ABSTRACT

    The acoustic theory of sound production and the harmonic series of the French

    horn are examined.

    A summary of how brass instruments function acoustically is presented and

    related to the theory of resonance in closed-open cylindrical pipes.

    The harmonic series produced by a horn is measured and analysed with an FFT

    analyser.

    The horn is modified with various lengths of cylindrical hosepipe to study the

    effect of the conical mouthpiece and mouthpipe and the flaring bell separately.

    The experiments indicate that the mouthpiece, mouthpipe and bell modify the

    tuning of harmonics of the simple cylindrical pipe in a frequency-dependent

    manner.

    The lowest note playable on the horn is found not to be a natural resonance of

    the instrument, but a heterodyne tone produced by interaction between the upper

    harmonics. This note is called the pedal note.

    The mouthpiece and mouthpipe have a relatively small effect on the tuning. The

    bell significantly changes the tuning of the lower harmonics so that the horn

    appears to play a full set of odd and even harmonics from the pedal note

    upwards.

  • A STUDY OF FRENCH HORN HARMONICS PAGE 4 OF 78

    ACKNOWLEDGEMENTS

    I would like to thank the following people:

    Dr Bob Peters and Hansa Parmar at the IoA for a very enjoyable year studying the

    IoA Diploma.

    My colleagues at AJA for general encouragement, their (apparent!) interest, and

    putting up with the dreadful noises required to produce this project! Particular thanks

    to Andy Pearce for proofreading.

    Stephen Cox for the loan of textbooks.

    Andy Taylor of Taylor Trumpets for a very interesting discussion on the subject of

    instrument building.

    Last, but not least, Sarah, Anna and Emily for their love and support.

  • A STUDY OF FRENCH HORN HARMONICS PAGE 5 OF 78

    CONTENTS

    1 INTRODUCTION.......................................................................................................................... 7 1.1 SCOPE ............................................................................................................................................... 7

    1.2 STRUCTURE OF THIS PROJECT............................................................................................................ 7

    1.3 A NOTE ON NOMENCLATURE ............................................................................................................. 8

    2 THE FRENCH HORN ................................................................................................................ 10 2.1 ORIGINS AND DEVELOPMENT .......................................................................................................... 10

    2.2 THE MODERN INSTRUMENT............................................................................................................. 14

    2.3 METHOD OF PLAYING...................................................................................................................... 16

    2.4 NOTES PRODUCED BY THE INSTRUMENT ......................................................................................... 19

    2.5 REPERTOIRE.................................................................................................................................... 19

    2.6 QUIRKS OF THE INSTRUMENT .......................................................................................................... 20

    3 THE PHYSICS OF SOUND PRODUCTION ........................................................................... 22 3.1 OVERVIEW ...................................................................................................................................... 22

    3.2 THEORY THE CLOSED-OPEN CYLINDRICAL PIPE ............................................................................ 23

    3.3 THEORY THE CLOSED-OPEN CONICAL PIPE ................................................................................... 24

    3.4 INPUT IMPEDANCE .......................................................................................................................... 26

    3.5 PRODUCING THE VIBRATIONS - THE FUNCTION OF THE LIPS ............................................................. 27

    3.6 NON-LINEARITY OF THE LIP VIBRATION ........................................................................................... 29

    3.7 REGIMES OF OSCILLATION ............................................................................................................ 29

    3.8 PEDAL NOTES.................................................................................................................................. 31

    3.9 EQUIVALENT CONE LENGTH ............................................................................................................ 32

    3.10 SECTIONS OF THE INSTRUMENT ....................................................................................................... 34

    3.11 MOUTHPIECE AND MOUTHPIPE........................................................................................................ 34

    3.12 CYLINDRICAL TUBING ..................................................................................................................... 36

    3.13 VALVES / TUNING SLIDES ................................................................................................................ 37

    3.14 FLARE / BELL .................................................................................................................................. 37

    4 EXPERIMENTS .......................................................................................................................... 42 4.1 OVERVIEW ...................................................................................................................................... 42

    4.2 METHODOLOGY .............................................................................................................................. 42

    4.3 MEASUREMENT EQUIPMENT AND ANALYSIS.................................................................................... 44

    4.4 RESULTS HORN............................................................................................................................. 46

    4.5 RESULTS HOSE MOUTHPIPE / HOSE BELL....................................................................................... 48

    4.6 RESULTS HORN MOUTHPIPE / HOSEPIPE BELL................................................................................ 51

    4.7 RESULTS HOSE MOUTHPIPE, HORN BELL ....................................................................................... 54

  • A STUDY OF FRENCH HORN HARMONICS PAGE 6 OF 78

    5 ANALYSIS ................................................................................................................................... 57 5.1 GENERAL OVERVIEW ...................................................................................................................... 57

    5.2 THE LOWEST HARMONIC ................................................................................................................. 58

    5.3 MEASURING THE REAL FUNDAMENTAL ........................................................................................... 61

    5.4 EFFECT OF THE HORN MOUTHPIPE ................................................................................................... 65

    5.5 EFFECT OF THE BELL ....................................................................................................................... 67

    5.6 SOURCES OF ERROR ........................................................................................................................ 68

    5.7 FURTHER WORK .............................................................................................................................. 68

    6 CONCLUSIONS .......................................................................................................................... 70

    APPENDIX A REFERENCES / BIBLIOGRAPHY....................................................................... 71

    APPENDIX B INSTRUMENT MANUFACTURE ........................................................................ 72

    APPENDIX C - MEASURING EQUIPMENT .................................................................................. 75

    APPENDIX D CD CONTENTS ....................................................................................................... 76

    APPENDIX E GLOSSARY OF TERMS ........................................................................................ 78

  • A STUDY OF FRENCH HORN HARMONICS PAGE 7 OF 78

    1 INTRODUCTION

    There cannot be many brass players who have not tried to play a piece of hosepipe

    for fun at some point in their careers. The procedure is simple place the

    instruments mouthpiece in the end of the hose, a kitchen funnel at the other end,

    and literally minutes of amusement are sure to follow.

    An interested party might notice that the hosepipe instrument plays a slightly

    dif