Fluctuation Strength Reference
Return the modulation-rate context and limitations of psychoacoustic fluctuation strength.
Description
Fluctuation strength is generally strongest for slow amplitude modulation near 4 Hz under reference-like conditions.
Fluctuation strength is generally strongest for slow amplitude modulation near 4 Hz under reference-like conditions. 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 Fluctuation Strength Reference
Use Fluctuation Strength Reference when you need to evaluate the supplied records under the calculation and evidence rules below. Carrier spectrum, level, modulation depth, duration, and method affect the result, so 4 Hz is not a universal measured maximum. 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 Fluctuation Strength 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 "peak-rate", "unit", "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 |
|---|---|
| peak-rate | source: Zwicker and Fastl psychoacoustics literature; statement: Fluctuation strength is generally strongest for slow amplitude modulation near 4 Hz under reference-like conditions.; topic: peak-rate |
| unit | source: Zwicker and Fastl psychoacoustics literature; statement: Fluctuation strength is reported in vacil; one vacil is defined by a specified reference modulation sensation.; topic: unit |
| caution | source: Psychoacoustic fluctuation-strength methods; statement: Carrier spectrum, level, modulation depth, duration, and method affect the result, so 4 Hz is not a universal measured maximum.; 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 "peak-rate", "unit", "caution" |
{
"input": {
"topic": "peak-rate"
},
"output": {
"source": "Zwicker and Fastl psychoacoustics literature",
"statement": "Fluctuation strength is generally strongest for slow amplitude modulation near 4 Hz under reference-like conditions.",
"topic": "peak-rate"
}
}Limitations and assumptions
Carrier spectrum, level, modulation depth, duration, and method affect the result, so 4 Hz is not a universal measured maximum. 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 Amplitude Modulation Depth: Peak-to-trough sound-level modulation depth summarizes variation between two measured levels. An explicit threshold gives a simple amplitude-modulation screen. For a complementary task, use Band Loudness Aggregation: Loudness from several bands may be combined with an explicitly chosen coupling factor. The dominant band and sum of remaining bands must already be supplied in sones.
References
-
Fluctuation Strength Reference — tool.io
Similar or alternative tools
- Amplitude Modulation Depth
Peak-to-trough sound-level modulation depth summarizes variation between two measured levels. An explicit threshold gives a simple amplitude-modulation screen.
- Band Loudness Aggregation
Loudness from several bands may be combined with an explicitly chosen coupling factor. The dominant band and sum of remaining bands must already be supplied in sones.