terça-feira, 25 de dezembro de 2012



10. Conclusions

Our investigations confirmed that respiratory acts in wind instrument playing derives their characteristics from three different realms, (1) the acoustical properties of the instrument, (2) the physiological characteristics of the player, and (3) the musical demands of the score. This supports the assumption that an interdisciplinary approach to the study of sound production in wind instruments is likely to yield more information and to open new perspectives, promoting understanding of several, otherwise confusing and intangible issues.

Here follows conclusions ordered according to the papers presented.

Paper I

  • Blowing pressures represent a factor of major relevance to playing.
  • Blowing pressure is varied systematically with dynamic level and fundamental frequency in the instruments studied; these dependencies seemed consistent within as well as between players
  • In doublereed instruments pressure was increased with fundamental frequency while in the clarinet the pressure tended to decrease with fundamental frequency within each register and in the saxophone, it was varied according to a pattern similar to that of doublereeds in the lowest octave, and similar to that of the clarinet in the higher range.

Paper II

  • The hardness of the reed affects various input parameters, harder reeds require higher airflow, blowing pressure and tend to produce tones of higher SPL.
  • Airflow systematically increased with blowing pressure and dynamical level in all instruments.
  • Players tend to simultaneously increase blowing pressure and decrease the tightness of the embouchure, when they increase dynamical level. For constant embouchure an increased blowing pressure produces a softer tone.
  • Intense vibrato in reed woodwinds was associated with comparatively wide pressure undulations. These undulations cannot be produced merely by the laryngeal mechanism described in previous studies but rather with participation of expiratory forces.

Paper III

  • During playing wind instruments the content of CO2 in the expired air varies between the ambient level and up to 8.5% in extremely long phrases, while for the O2 it may vary from the ambient 21% down to 12%, or even less.
  • The increase in CO2 tends to lower the pitch and the fall in O2 tends to raise it. The net effect is a pitch decrease.
  • Air humidity, on the other hand, changing at each new breath, tends to increase pitch.
  • The overall effect of these factors may account for a fall in fundamental frequency by more than 15 cents.
  • The player may compensate for these relevant pitch effects by means of the embouchure and blowing pressure.

Paper IV

  • The non-invasive RIP method revealed to be robust and reasonably accurate also when applied to wind instrument playing.
  • Spirometry indicated that the relationship between the RIP output and lung volume was linear within the typical ranges used in reed woodwind instrument playing.
  • Artefacts were caused by posture changes and by the compression of the respiratory system required at high expiratory pressures. Compression artefacts can be partly compensated for by postprocessing of the data, taking the blowing pressure into account.
  • Initiation lung volume (ILV) typically ranged between 55% and 87% of vital capacity (VC) in the pieces tested.
  • For instruments that require blowing pressures in the range of the relaxation pressures, i.e. up to 40 cmH2O approximately, termination lung volume (TLV) reached values close to 0% VC in extreme cases.
  • For instruments requiring higher blowing pressures such as the oboe, TLV values below rest end-expiratory level (REL) were rarely observed.
  • During a highly demanding piece inhalation breath pauses were typically about 300 ms long and synchronised with increases of the RC and AW signals
  • The RIP method, at least when complemented by spirometry and constant-flow procedure, should be useful for future research as well as for pedagogical purposes.

Paper V

  • The factors involved in the perception of blowing pressure are complex and not easily isolated from each other, as these pressures are sensed by different organs and mechanisms.
  • Still, reproducible and consistent data were obtained from highly trained players.
  • The relationship between stimulus and perception was quasi-linear in almost all cases; a power function with the exponent generally close to 1.0 also represented an acceptable model. The power function exponents were mostly positively correlated to lung volume.
  • Sensation of blowing pressure alone seems to provide an important clue for the musician's control of the instrument.
  • Considerable inter-subject differences were found in estimated sensitivity; therefore, mean values are not adequate for predicting the behaviour of individual subjects.
  • Psychophysical methods seem useful for assessment of playing abilities in players, and possibly for evaluating specific training programs designed to improve respiratory control in performance.

Paper VI

  • The particular phonatory mode investigated in this exploratory study was associated with simultaneous oscillations of the vocal folds and the ventricular folds.
  • The effect is similar to that produced in the Tibetan chant tradition, according to an expert listener.
  • The frequency ratio between vocal and ventricular folds was 2:1 or, in some cases, 3:1.
  • The closure of the ventricular folds occurs during the open phase of the vocal folds, thus damping every second or third glottal pulse.
  • The driving of the ventricular folds seems to be a negative pressure generated by the airstream contained in the glottal pulse.
  • The subglottal pressures required were consistently higher than those used in modal and pulse register, at least in the subject used in this experiment.
  • The fundamental frequency range approached one octave starting at 49 Hz (G1), approximately. The SPL measured at 0.3 m could be varied within 64 and 88 dBA for the 58Hz (Bb1) tone.
  • This technique can also be employed in wind instruments playing, producing a family of new sounds.

    ©1998 by Leonardo Fuks



Nenhum comentário:

Postar um comentário