NOTES ON ACOUSTICS 63

Acoustics has been defined as the science of auditory vibrations. It has also been defined as the qualities of a room or theater that determine how well a sound can be heard. What a singer knows about acoustics is generally limited to what he has learned through experience. Eventually he becomes aware that some places are easier to sing in than others. What he unconsciously listens for when he sings is a reflection of how his voice is sounding.

This reflection is call¬ed reverberation, which may be defined as a reflection of sound waves in a confined area.w The length of time that a sound can be heard in a closed area is called the reverberation time of that area. When applied to singing, if the reverberation time of a room is too short, that is, if the sound waves die out too quickly, then the singer's voice will sound lifeless and non-re son -ant to him and to the audience. If the reverberation time is too long, that is, if the sound waves keep sounding, then the singer's voice will sound too live, and interfere with the sounds coming after.

An optimum reverberation time, which will vary with the size of a room or theater and the character of the walls and furnishings, will be the most satisfying to the performer and to the audience.64 There is usually no reverberation in outdoor singing where loud sounds are quickly dissipated. In cases like these, the singer wonders if his voice carries. In small rooms with hard surfaces there is usually too much re¬verberation.

Here the singer may well get the impression that he is better than he actually is. The most satisfactory situation is where the singer's voice fits the optimum reverberation time of the room or theater. Here the singer's vocal production will seem to be effortless. In some instances it is possible to control poor acoustical conditions by sound reflectors and public address systems. Through the use of these aids a singer can learn to adjust his voice to fit the conditions, or depend on those operating the controls to do so.

The Vocal Mechanism65

The vocal mechanism may be said to be made up of bellows, vibrators, and resonators. The bellows-like action of the breathing mechanism fur¬nishes the power in the form of a pressure flow of the breath to activate the vibrators, the vocal cords. Through the resistance of the vocal cords as vibrators to the pressure flow of the breath, acoustical energy is produced in the form of sound waves which are transmitted upward to the resonators -the pharynx, mouth, and nasal passages.

Here the sound waves are changed into a singing quality, and a singing diction which should be considered as a part of the singing quality. The singing quality is made up of musical tones which have pitch, loud-ness, and quality. The musical tones are basically sound waves which have, from a physical standpoint, frequency, amplitude, and timbre. Frequency is the physical term for the number of vibrations of the sound waves, measured objectively. Pitch is the psychological term for the number of vibrations heard, and designated by letter names c, d, e, etc. A sub¬jective judgment.