The “Strike Notes” from Bells
Arthur Taber Jones · The Journal of the Acoustical Society of America · 1930
The “strike note” of a bell does not appear to be produced by vibration of the bell in any of its normal modes. The strike note is not far from an octave below the fifth partial tone of the bell, and the suggestion has been made that this fifth partial may come out with especial promptness and strength, and the attention of the ear be afterward quickly caught by lower tones, so that the tone from the fifth partial is judged to be an octave lower than it really is. Several tests of this hypothesis have been attempted. (1) A number of musicians have given their judgment as to the pitches of the strike notes on three bells. The average is almost exactly an octave below the fifth partial. (2) The sounds from six bells have been picked up from a distance of about 300 meters. When the bells were struck so gently as to be almost inaudible at this distance, beats from suitably tuned forks showed that the fifth partial is at least as prominent as any other. (3) On the same six bells the first order difference tone from the fifth and seventh partials is close to the strike note. (4) The time during which the clapper is in contact with the bell has been found rather roughly for one bell. This time is not far from half the period of the fifth partial. The results of other tests are not yet sufficiently definite to be of significance. The work is to be continued next summer.