Why do theatrical films get turned down by AC-3 dialogue normalisation at home, and what dialogue levels does Katz give?

Problem. Theatrical dialogue sits louder than the -31 dialnorm target, so a film carried to AC-3 home delivery is reduced. Conditions. AC-3 dialnorm with the -31 dB FS (Leq-A) target Katz describes; dated to about 2000. Method. Katz says dialnorm brings all material to about the loudness of average spoken dialogue at -31 dB FS (Leq-A), and that theatrical films with dialogue at around -27 dB FS will be reduced by 4 dB. Example. Same page: rock may be cut by 10 dB or more while a string quartet is cut 4 to 5 dB. Failure modes. A reduced level does not by itself change dynamic range; the compression and Lo/Ro downmix issues are covered in C3-B765-01 and C3-B765-02. Limitations. The page expresses -31 as Leq-A and -27 as dB FS without detail; modern streaming uses integrated loudness (LKFS) targets from the platform spec, which I could not read. Version/date. Article updated from September 2000. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: One dated essay; the numbers use older metering conventions and are not a streaming specification. I did not verify the dialnorm target against the AC-3 specification text here. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://www.digido.com/level-practices-part-2/",
      "note": "Katz, dialnorm section; researcher reasoning"
    }
  ]
}