As the title indicates, the picture above is taken from Morton Feldman's Rabbi Akiba (1963) for flute, English horn, horn, trumpet, trombone, tuba, soprano, percussion, celeste, cello and double bass. I recently happened upon the score and found this particular page to be highly intriguing.
First, there are four quietly articulated, sustained sonorities, each separated by a measure of rest. This seems straightforward. However, the limited rhythmic activity does not clearly imply a meter or tempo despite the fact that both the meter and tempo change every bar. And although all of the measures with chords are in 3/2, the changes in tempo ensure that none of them are of equal duration. Lastly, the note value upon which the tempo is based shifts from a quarter note to a half note in two of the measures. I think it is safe to reason that if one were to take dictation from a performance of this passage, one's notation would differ from the original just a bit. To gain a better understanding of why Feldman may have presented the sounds in this way, it is helpful to look at other passages.
Throughout Rabbi Akiba moments like the one above are interspersed with unmeasured sections where the rhythmic durations of sustained notes and chords are not indicated. Instead, pitch durations are determined by the natural decay of a given instrument or voice. The rate of decay further informs when the next sound enters. Feldman writes, "Each instrument enters when the precding sound begins to fade." In these unmeasured sections, consecutive sounds are connected with a broken line (see score example at right).
As a result, duration of pitches (i.e. how long a crotale rings, the amount of time a wind player or vocalist can sustain a note) will vary much like the highly irregular lengths of pitches and rests in the measured page above. Measured or unmeasured, both types of notation successfully avoid pulsation and yet manage to convey a certain coherence and regularity. Perhaps this relates to Feldman's statement that "I am interested in getting to Time in its unstructured existence. That is, I am interested in how the wild beast lives in the jungle - not in the zoo."*
Unfortunately, Rabbi Akiba has never been recorded. One can, however, hear how this approach to notation would sound by listening to de Kooning, another Feldman piece written in 1963. Both works alternate between measured and unmeasured sections and are composed for similar instrumentations. (Listen to excerpt of de Kooning below)
Some might hear the results as a sort of loosely tethered klangfarbenmelodie. I personally like the way in which pieces like Rabbi Akiba and de Kooning require the performers to listen very carefully to one another in order to properly connect their own notes with those that are expiring. To a large extent it is the expiration of sounds or rather the dissipation of sounds back into silence that serves as the basis of these pieces. Silence is almost like another timbre, cleansing the palate of the previous sound while providing contrast. In his essay "The Anxiety of Art," (1965) Feldman writes, "The attack of a sound is not its character. Actually, what we hear is the attack and not the sound. Decay, however, this departing landscape, this expresses where the sound exists in our hearing - leaving us rather than coming toward us."
*Quote taken from Feldman's essay "Between Categories" (1969).