Index of Sustained Resonances

The Index of Sustained Resonances is a bound register maintained by the Department of Aural Resonances at the behest of the Committee for Aural Integrity, recording every resonance judged to have persisted beyond the sixty-day threshold set by Concordance 45. It is distinct from the Alphanumeric Index, which records only those echoes that dissipate according to predicted curves, and from the Register of Protected Tones, which lists tones the Tower undertakes to preserve rather than merely to observe. The Index presently comprises forty-one volumes and three supplemental fascicles, the third of which has been in preparation since the winter of 11,880 and is not expected to close.

Scope and method

An entry is opened when a sustained phenomenon has been confirmed by two independent listeners posted no fewer than nine floors apart. The entry records the floor of origin, the date of first audit, the duration in days, and a short description in the standard restrained idiom. Duration is reckoned in days rather than hours because the Bureau of Classification determined in 11,204 that hourly reckoning encouraged "a false precision in the record and an unseemly impatience in the auditors" (Bureau of Classification, Memorandum 61-C).

The Index does not adjudicate whether a resonance is real. It records only that it was heard, by whom, and for how long. This distinction, first drawn in Protocol for Sustained Engagement and reaffirmed in every recension since, has spared the Department a considerable volume of litigation.

Relation to other holdings

Sustained Resonances are indexed separately from Oneiric Resonances, though the two categories overlap in practice and the Department has never resolved the overlap to general satisfaction. A resonance that both persists beyond sixty days and exhibits the incompatible dream-logics characteristic of the oneiric class is entered twice, once in each register, with a cross-note in the margin. The margin notes are not themselves indexed, a fact that has caused difficulty on at least four documented occasions.

Cross-Referential Resonances are excluded from the Index outright, on the ground that a citation loop is a defect of the catalogue rather than a phenomenon of the floor. Referential Fumigation is applied and the matter is considered closed. The Kettleman Copy Resonances near the primary ratified exemplar of the Third Concordance are likewise excluded, under a standing exemption granted in 11,455 and never reviewed.

The Floor 770 discrepancy

A persistent scholarly disagreement concerns the status of Coincidental Resonances. The Alphanumeric Index holds, on the strength of its own founding annotation, that echoes dissipating along predicted curves are a separate order of thing and should not appear in a register of sustained phenomena. The Department of Aural Resonances has argued since 11,617 that a curve is a description, not a category, and that a resonance which followed a predicted curve for sixty-one days was sustained by any plain reading of the word.

"The curve describes what was expected. The Index describes what was heard. The Department has never been asked to index expectations."

— Librarian Ossia Vane, Dissent appended to Concordance 45, Annex 9

No resolution has been reached. In practice, auditors on Floor 770 enter such resonances in the Alphanumeric Index and pencil a note in the margin of the Sustained Index directing the reader elsewhere. The pencil notes are erased annually and rewritten.

The Vane Recension and the Office dispute

Vane's successor as Keeper of the Index, Librarian Halvern Cusk, undertook a full recension in 11,702, renumbering all entries by floor rather than by date of audit. The recension was thorough and is now regretted. Because floor numbers are not sequential in any reconstructible order, the volumes no longer open onto any coherent period, and an auditor wishing to trace a single winter's work must consult as many as eleven volumes.

The recension also brought the Index into conflict with the Office of Sustained Lamplight, which had for two centuries supplied lamps to the Index room on the understanding that the register was consulted chiefly at night. Cusk's renumbering moved the most-consulted volumes to a shelf beyond the lamplight's reach. The Office declined to extend the supply, observing that "the Index has been renumbered; the wicks have not" (Office of Sustained Lamplight, Letter 88 to the Committee for Aural Integrity). The Department has since conducted its evening audits by damped lantern and complaint.

Use and known hazards

The Index is consulted under the ordinary provisions of the Protocol for Sustained Engagement. Readers are reminded that prolonged study of a sustained entry may itself produce a faint sympathetic tone in the reader, which the Department does not regard as a resonance and will not index. Ætheric Earplugs are issued at the desk and must be returned. Food is not permitted in the Index room, and has not been since the Cusk recension, for reasons the Department has declined to state in writing.

Three volumes remain unaccounted for: XVII, XXIX, and the second supplemental fascicle. The Department's position, unchanged since 11,790, is that they were never issued and that the gaps in the shelf are a matter of binding rather than loss.