EDT and Late-Decay Reference

Distinguish early decay time from later reverberation-time regressions defined by ISO 3382.

Description

EDT is derived from the initial 0 to -10 dB decay slope and extrapolated to a 60 dB decay time; it emphasizes the early subjective decay.

EDT is derived from the initial 0 to -10 dB decay slope and extrapolated to a 60 dB decay time; it emphasizes the early subjective decay. 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 EDT and Late-Decay Reference

Use EDT and Late-Decay Reference when you need to evaluate the supplied records under the calculation and evidence rules below. The reference does not measure, model or certify the supplied situation. 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 EDT and Late-Decay 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 "edt", "t20", "t30"	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
edt	source: ISO 3382-1; statement: EDT is derived from the initial 0 to -10 dB decay slope and extrapolated to a 60 dB decay time; it emphasizes the early subjective decay.; topic: edt
t20	source: ISO 3382-1; statement: T20 is obtained from a regression over -5 to -25 dB and extrapolated to 60 dB; it is not a literal 20 dB reverberation time.; topic: t20
t30	source: ISO 3382-1; statement: T30 is obtained from a regression over -5 to -35 dB and extrapolated to 60 dB; adequate decay range and regression quality are required.; topic: t30

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 "edt", "t20", "t30"

json

{
  "input": {
    "topic": "edt"
  },
  "output": {
    "source": "ISO 3382-1",
    "statement": "EDT is derived from the initial 0 to -10 dB decay slope and extrapolated to a 60 dB decay time; it emphasizes the early subjective decay.",
    "topic": "edt"
  }
}

Limitations and assumptions

The reference does not measure, model or certify the supplied situation. 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 Music Clarity C80: Clarity C80 compares impulse-response energy arriving within the first 80 ms with later energy. A larger value indicates a stronger early-to-late balance on this definition. For a complementary task, use Speech Clarity C50: Clarity C50 compares impulse-response energy arriving within the first 50 ms with later energy. It uses a different cutoff from C80.

References

EDT and Late-Decay Reference — tool.io

Similar or alternative tools

Music Clarity C80
Clarity C80 compares impulse-response energy arriving within the first 80 ms with later energy. A larger value indicates a stronger early-to-late balance on this definition.
Speech Clarity C50
Clarity C50 compares impulse-response energy arriving within the first 50 ms with later energy. It uses a different cutoff from C80.