ASTC Field-Rating Reference

Distinguish apparent field sound-transmission ratings from laboratory STC without offering a false fixed conversion.

Description

ASTC is an apparent field rating that includes sound transmitted by the separating assembly and associated flanking paths.

ASTC is an apparent field rating that includes sound transmitted by the separating assembly and associated flanking paths. This reference explains the selected concept and the evidence needed to interpret it.^[1]

The returned values include Source, Statement, Topic. The How section below explains the calculation, input rules and interpretation.

When to use ASTC Field-Rating Reference

Use ASTC Field-Rating Reference when you need to evaluate the supplied records under the calculation and evidence rules below. There is no universal numeric conversion from STC to ASTC; construction, junctions, workmanship, room conditions, and flanking control determine the field result. This is an introductory excerpt, not the complete standard, a current compliance check or a project-specific calculation.

Choose the measured quantities, units, weighting and measurement basis before entering values. For a reference, select the exact topic. For a catalog lookup, prepare complete source-backed records; for a screen, select an applicable caller limit.

How to use ASTC Field-Rating Reference and understand its results

Choose the measured quantities, units, weighting and measurement basis before entering values. For a reference, select the exact topic. For a catalog lookup, prepare complete source-backed records; for a screen, select an applicable caller limit.
Enter topic using the field table and calculation rules, then run the tool.
Read source, statement, topic. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
topic	Reference topic to return.	string; one of "astc", "stc", "caution"	Required

Choose one of the exact topic values in the table. The tool indexes a fixed, locally embedded reference entry and returns its source label, statement and unchanged topic. It does not fetch the source or update the wording. Topic meanings and all returned entries are shown below.

Selection	Returned reference entry
astc	source: ASTM E336 and ASTM E413; statement: ASTC is an apparent field rating that includes sound transmitted by the separating assembly and associated flanking paths.; topic: astc
stc	source: ASTM E90 and ASTM E413; statement: STC is derived from laboratory transmission-loss measurements of a test specimen under ASTM E90 and classified under ASTM E413.; topic: stc
caution	source: ASTM E336; statement: There is no universal numeric conversion from STC to ASTC; construction, junctions, workmanship, room conditions, and flanking control determine the field result.; topic: caution

selected exact topic → embedded source label, explanatory statement and topic

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
source	Source used for the reference statement.	string
statement	Narrow reference statement for the selected topic.	string
topic	Selected reference topic.	string; one of "astc", "stc", "caution"

json

{
  "input": {
    "topic": "astc"
  },
  "output": {
    "source": "ASTM E336 and ASTM E413",
    "statement": "ASTC is an apparent field rating that includes sound transmitted by the separating assembly and associated flanking paths.",
    "topic": "astc"
  }
}

Limitations and assumptions

There is no universal numeric conversion from STC to ASTC; construction, junctions, workmanship, room conditions, and flanking control determine the field result. This is an introductory excerpt, not the complete standard, a current compliance check or a project-specific calculation.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Extremely large text inputs are rejected. Missing fields without a declared default, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Flanking Junction Record Lookup: A junction record may contain direct and apparent sound ratings plus a separately documented correction. Missing ratings should remain explicitly unavailable. For a complementary task, use Layered Gypsum Wall STC Lookup: A wall STC rating belongs to a particular complete tested assembly. Similar materials alone do not establish an interchangeable rating.

References

ASTC Field-Rating Reference — tool.io

Similar or alternative tools

Flanking Junction Record Lookup
A junction record may contain direct and apparent sound ratings plus a separately documented correction. Missing ratings should remain explicitly unavailable.
Layered Gypsum Wall STC Lookup
A wall STC rating belongs to a particular complete tested assembly. Similar materials alone do not establish an interchangeable rating.