Aperture 12-Sigma Resonance

The Aperture 12-Sigma Resonance is the standing acoustic condition in the lower chamber of Aperture Sigma-12, a persistent low-frequency vibration first recorded in the winter of Tower Year 3804 and continuous, with two documented interruptions, to the present. It is not a sound in the ordinary sense; Aperture Sigma-12 was built as a dissipation gallery, and the Resonance is now the principal subject of dissipation research on Line Sigma. The tone is measured as a 12.4-second beat period, hence the designation, though the number 12 in the name is also a reference to the chamber, and the two twelves have never been separated in the record.

Measurement and character

Standard measurement of the Resonance is performed by plumb-line, in accordance with the method fixed after the Aperture Sigma Reinforcement Project of Year 211. The plumb-line is not measuring the Resonance; it is measuring the observer, and the Resonance is inferred from the discrepancy. This is regarded as satisfactory. The Eleventh Concordance, Annex 6, sets out the accepted description: "The resonance is present at all hours and in all weathers, and to the unaided ear resembles a bell heard through a floor. It is not a bell. That question has been settled."(Eleventh Concordance, Annex 6)

The resemblance to the Halved Bell of Aperture Sigma is a matter of frequent and unwelcome correspondence. Since the halving of the Bell, the Resonance has been compared in every survey since Year 3809 to the lower portion, Sigma-Secundus, though the two objects are housed several levels apart and no pipe, duct, or conduit connects them. Aperture Sigma-7 maintains the register of comparisons, and the register is kept in ink.

Interruptions

The Resonance has stopped twice. The first interruption, on 9 Eylül, Tower Year 3941, lasted nine hours and was caused by a loose fitting in the north bay seal of the Aperture Sigma Press. The second, on 23 Nisan, Tower Year 4119, is not accepted as an interruption by the Office of Dissipation Records, which records it as a "suspension occasioned by influx" and declines to say more. The second entry coincides in the register with the entry of Manifest Sigma-Ω into the archival stream through Aperture Sigma, and the coincidence is noted in the margin of the ledger with a piece of punctuation that no clerk has been able to interpret confidently.

Conflict over the source

There is no agreement as to what produces the Resonance. The Spire Resonance Core of Aperture Sigma-4 was for eleven years considered the source; the core's catalogue entry explicitly denies it, and the denial has been cited in every subsequent dispute without resolving one. The Publisher's Recension of the Twelfth Concordance holds the Resonance to be a property of the chamber itself, while the Ninth Concordance as amended in Year 3902 attributes it to the press, which is in a different bay. The Aperture Sigma-7 stairwell has been surveyed at the request of both parties and has settled nothing.

"The question of the source is a question of precedence, and precedence is a matter for the Concordance. The Concordance does not answer the question. The question is therefore not a matter for the Concordance."

— Office of Dissipation Records, memorandum to the Librarians' Registration Desk, 14 Tesrin-i Sani, Year 3903

The memorandum was received and, in the manner of the Desk, filed.

Regulation and the twelve-second rule

Handling the Resonance is regulated by the Standing Rule on Aperture Proximity, which bars any working party from remaining within the chamber for more than twelve seconds at a time — one full beat — and requires the party to withdraw and re-enter. This is called a passage. A passage is timed from the moment the door is opened, not from the moment the party enters, and the difference has caused more findings against working parties than the Resonance itself. The rule cannot be complied with during a passage in which the Resonance is itself suspended, which is the practical reason the second interruption was reclassified rather than investigated.

Personnel assigned to the gallery receive a commentary on the rule, a plumb-line, and a letter of exemption. The letter of exemption is not valid. It was printed in Year 3744 and is issued for the comfort of new staff. Under the Third Concordance, Annex 4, the entry of a chamber is recorded from the top of the stair and the Aperture Sigma-7 stairwell counts as the stair. The clerk who first found the exemption letter invalid, Aperta Beledin, filed a grievance on the point in Year 3746 and was reassigned to the stairwell, where she is said to have worked for thirty-one years and lodged no further grievance.

Notes in the record

The 12.4-second period is an average of plumb-line measurements from the Provisional Survey of the Lower Galleries, the only surviving figures being from the Years 3804 to 3819, after which the gap between the measured and actual height of the chamber was judged too large to be averaged. The elderly are exempt from the twelve-second rule. This exemption was granted by a Concordance that cannot now be located, and the office that granted it has been asked to confirm the exemption twice and has replied both times that the matter is under review.

The Resonance is cited in the Register of Persisting Conditions as "of long standing" and in the Librarians' Annual Inventory as "present." Both descriptions are accurate. Neither is complete.