An exploration of extreme high notes in brass playing

Some of the most striking examples of playing at the extremes of the high register of a brass instrument can be heard in modern commercial trumpet playing. Many other examples of very high brass playing are also found in the clarino writing for trumpets and orchestral horns in the late 17th and early 18th centuries. A distinctive acoustical feature of this style of playing is that the notes sounded are above what is normally considered to be the cut-off frequency of the instrument. This means that there is little or no reflection of the pressure wave from the bell of the instrument back to the player's lips, which is a requirement for establishing a strong coupling between the lips and the air column. Below the cut-off frequency, the threshold pressure for a played note is lowest close to one of the air column resonance frequencies; the corresponding experience of the player is that the lips are guided into pitch 'slots' close to the resonance frequencies. However, skilled players frequently claim that they can also experience distinct 'slots' when playing in the extremely high register. This paper explores three different approaches for investigating the physics of the lips, air column and resonator in playing extreme high notes: a recently developed multiple microphone technique has been applied to the separation of the forward and backward going waves in an instrument under playing conditions, high speed filming of the player's lips using specially designed mouthpieces with optical access has been utilised to examine the mechanics of brass playing in the high register, and a study has been undertaken of the transfer function between mouthpiece and bell at high frequencies and high amplitudes.