Chamber of Anticipated Sound

The Chamber of Anticipated Sound is the Tower's principal instrument of acoustic foresight, a vaulted hall on Floor 407 in which a sound is admitted, measured, and certified one to three minutes before it has occurred. It is not a place of silence, nor of performance; the Chamber produces nothing audible of its own. Its whole function is to receive, at volume, sounds still owed to the future, and to grade them so that the archive may know what it is about to hear.

The present Chamber was raised in the winter of the year recorded as 612 after the first inventory, replacing an earlier, smaller apse that had been condemned after it began anticipating sounds that were never subsequently owed. The apse was sealed and its furnishings left in place. Visitors are advised not to speak in the stairwell leading down to it, as the stairwell anticipates replies.

Doctrine and operation

The Chamber's governing text is The Hum of Continuity, which fixes both its monitoring protocols and the intervals at which its resonance floor is re-laid. Anticipation is produced by a chronostatic dampening field, of the same pattern employed at the Repository of Anticipated Forms, though differently tuned: where the Repository suppresses sound so that future forms may be examined, the Chamber permits a narrow forward siphon, admitted through the nine brass apertures of the west wall. Each aperture is keyed to a different lead time, from forty seconds to one hundred and eighty. The one-hundred-and-eighty aperture has not been opened since a Pre-emptive Audition conducted there in 781 brought forward a sound adjudged "of excessive length, and outside the Tower" (Dampening Field Survey, spiral 3, fol. 44).

Measured output is graded in Unheard Decibels (Ud); anticipations above 14 Ud require a second witness and a written justification, and anticipations above 30 Ud are entered in the Ledger of Sounds Not Owed, a volume whose margins are fuller than its entries. Where the nature of the sound is disputed — whether it is owed at all, or owed to a different floor — the matter passes to the Chamber of Acoustic Purity for Final Arbitration.

Dispute with the Chamber of Echoing Tomorrows

Jurisdictional friction with the Chamber of Echoing Tomorrows has been continuous since the Chamber of Echoing Tomorrows was granted its charter in 690. That body indexes anticipated reference materials; this Chamber anticipates sounds. The overlap, where an anticipated sound is itself a sound of reading, has never been resolved. Clerks of the one office are known to describe the other's holdings as "hearsay," while clerks of the other describe the first's as "silence with paperwork."

"Where a sound and its record both lie ahead of us, the record shall be catalogued by the Chamber of Echoing Tomorrows and the sound by the Chamber of Anticipated Sound, and neither shall be held to have anticipated the other."

— Ninth Concordance, Annex 6, clause 2

The clause was meant to settle the question and instead settled a third, unforeseen one: it obliged both Chambers to lodge simultaneous claims for the same event, which the Chamber of Auditors objected could not be reconciled, the Annex providing no order of precedence. The objection was entered, heard, and recorded as pending. It has been pending since 693.

Incidents

The most cited failure of the Chamber's history occurred on the night of 14 Frost, 748, when the forty-second aperture admitted a sound that recurred every eleven minutes for the remainder of the winter. Its source was traced to the re-laying of the quarry floor three storeys above, whose hammers had been scheduled, and then rescheduled, and then scheduled again. The repetition was not, strictly, an anticipation at all but a scheduling error arriving through the aperture in sequence. The then Keeper of the Apertures, Ovan Schist, filed a formal grievance against the Quarry Office that ran to forty pages and was answered, in full, after nine years. Schist died before the reply arrived; the reply anticipated his objection in fourteen of its eighteen clauses.

A quieter matter is the Hum of Anticipated Rain, catalogued at Floor -12: The Repository of Anticipated Forms and measured there with a Heissen-Marlo Resonator calibrated against a single drop striking the unvisited plinth in Sub-archive 72.8. The Chamber is sometimes mistakenly credited with housing the Hum. It does not. The Hum has been routed through the Chamber's north duct on three recorded occasions, each time in error, and each time returned within the hour.

Procedure and prohibition

Admission to the Chamber is by prior appointment only, and the appointment must be requested after the sound one wishes to hear has already been heard. An application submitted before the event is returned unopened. The Chamber's outer door is operated by a bell that has not yet rung, and the attendant opens it by hand.

On entering, visitors leave their voices at the threshold in the custody of the Wardens of the Threshold, who issue a numbered tally. The tally is not always returned. Where a visitor's voice is not recovered, the Wardens issue a certificate of retention that may be presented to the Chamber of Acoustic Purity should the voice later be required for a classification.

Scholarly disagreement

Whether the Chamber anticipates sounds or merely intercepts them early is the oldest quarrel in its literature. The received view, set out in The Hum of Continuity and defended in the Dampening Field Survey, holds that the Chamber's field draws forward a sound that would otherwise not yet exist at its floor — genuine anticipation, with the Chamber as cause as well as instrument. The opposing view, advanced by the Recensionists of Floor 22 and never formally refuted, holds that all sounds exist simultaneously in the fabric of the Tower and that the Chamber merely opens a door onto one of them, as one might open a door onto a room already furnished. On this reading the apertures are not apertures; they are windows, and the "anticipated" sound has simply been waiting.

The Second Concordance treats the question as one of classification and therefore outside its own competence; the Fifth forbids the Chamber to reopen the matter before the bell of the preceding argument has ceased to sound, which it has not. The disagreement is thus held, by both parties, to be anticipated.