Speech Transmission Index Method Reference
Summarize the scope and limitations of the standardized STI method.
Description
Speech Transmission Index uses modulation-transfer information across bands.
Speech Transmission Index uses modulation-transfer information across bands. Broadband SNR alone cannot supply its full standardized inputs.1
Summarize the scope and limitations of the standardized STI method.
When to use Speech Transmission Index Method Reference
Use this tool to summarize the scope and limitations of the standardized STI method.
Choose a supported reference topic, run an input-free reference with an empty object, or prepare the measured values and caller-supplied test records requested. Keep acoustic metrics, frequency, units and test conditions consistent.
How to use Speech Transmission Index Method Reference and understand its results
- Choose a supported reference topic, run an input-free reference with an empty object, or prepare the measured values and caller-supplied test records requested. Keep acoustic metrics, frequency, units and test conditions consistent.
- 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 "scope", "methods", "limitations" | Required |
Choose an exact topic enum from the input table and run the lookup. The implementation selects a fixed local entry and returns source, statement and the selected topic. Matching is case-sensitive without trimming or free-text search.
result=stored entry for selected 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 "scope", "methods", "limitations" |
{
"input": {
"topic": "scope"
},
"output": {
"source": "IEC 60268-16:2020",
"statement": "STI rates speech-transmission quality from reductions in modulation transfer across octave bands; it is not calculated from broadband signal-to-noise ratio alone.",
"topic": "scope"
}
}Limitations and assumptions
No STI, STIPA, modulation transfer or intelligibility measurement is calculated. The source is a stored bibliographic label, not a fetched document; statements are not refreshed at runtime.
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 required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use STI to CIS: Convert a positive Speech Transmission Index to Common Intelligibility Scale using CIS = 1 + log10(STI). For a complementary task, use Speech SNR Screen: Calculate speech-to-noise level difference and compare it with an explicit caller-supplied minimum.
References
Similar or alternative tools
- STI to CIS
Convert a positive Speech Transmission Index to Common Intelligibility Scale using CIS = 1 + log10(STI).
- Speech SNR Screen
Calculate speech-to-noise level difference and compare it with an explicit caller-supplied minimum.