{ "openapi": "3.1.1", "info": { "title": "Noise Generator (white, pink, brown) API", "version": "1.0.0", "summary": "Make white, pink, brown, blue or violet noise as a WAV file and check its spectrum.", "description": "Every endpoint performs the same calculation as the human page and returns inputs, result, units, assumptions, sources, warnings and computedAt. MCP endpoint: /mcp." }, "servers": [ { "url": "https://soundscapenoisegenerator.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Make white, pink, brown, blue or violet noise as a WAV file and check its spectrum.", "description": "Generates coloured noise with the correct spectral slope (white 0, pink −3, brown −6, blue +3, violet +6 dB per octave) as a downloadable WAV, mono or decorrelated stereo, 8–96 kHz, with level, fades, seamless looping and a seed for repeatable files. The measured spectrum, slope and levels are reported so you can verify the colour.\n\nMethodology:\n- White noise: Gaussian random samples from a seeded sfc32 generator (Box–Muller), so the power spectrum is flat.\n- Pink noise: white noise through a cascade of first-order pole/zero filters designed for the chosen sample rate (a pole every two octaves from 5 Hz, a zero half-way between), which averages −10 dB per decade = −3 dB per octave within about ±0.3 dB.\n- Brown noise: a leaky integrator (corner 10 Hz, so it never drifts) gives −6 dB per octave; blue noise inverts the pink filter (+3 dB); violet noise is the first difference of white noise (+6 dB per octave below about a quarter of the sample rate).\n- The level is set as RMS over all channels; if the highest peak would exceed −0.1 dBFS the gain is lowered and reported. Fades use an equal-power (sine) curve. Seamless loops render extra noise and crossfade it onto the start.\n- Check: the result is analysed with a Hann-windowed 4096-point Welch spectrum; the slope is a least-squares fit over 1/3-octave bands from 100 Hz to 10 kHz (or a quarter of the sample rate).\n\nStart playback quietly: noise at full level can damage speakers and hearing. Noise is not a medical sleep or tinnitus treatment.", "tags": [ "apps" ], "x-mcp-tool": "soundscape_noise_generator", "x-owner-app": "soundscape", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/SoundscapeNoiseGeneratorInput" }, "examples": { "example1": { "summary": "Pink noise, 5 s stereo, 44.1 kHz", "value": { "type": "pink", "duration": 5, "sampleRate": "44100", "channels": "stereo", "level": -18, "seed": "1" } }, "example2": { "summary": "Brown noise, 4 s mono loop at 48 kHz", "value": { "type": "brown", "duration": 4, "sampleRate": "48000", "channels": "mono", "loop": true, "level": -20, "seed": "sleep" } }, "example3": { "summary": "White noise test signal, 2 s mono, 32-bit float", "value": { "type": "white", "duration": 2, "sampleRate": "48000", "channels": "mono", "level": -12, "fadeIn": 0, "fadeOut": 0, "encoding": "float32", "seed": "42" } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/SoundscapeNoiseGeneratorResult" } } } }, "400": { "description": "Malformed JSON body.", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "422": { "description": "Invalid input (see errors[]).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "429": { "description": "Rate limit exceeded (see Retry-After).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } } } } }, "/api/v1/tool": { "get": { "operationId": "getToolDefinition", "summary": "Inputs, output schema and examples for this tool", "responses": { "200": { "description": "Tool definition.", "content": { "application/json": { "schema": { "type": "object" } } } } } } } }, "components": { "schemas": { "Problem": { "type": "object", "description": "RFC 9457 problem details. 422 responses include per-field `errors`.", "required": [ "type", "title", "status", "detail" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "status": { "type": "integer" }, "detail": { "type": "string" }, "code": { "type": "string" }, "errors": { "type": "array", "items": { "type": "object", "required": [ "field", "message" ], "properties": { "field": { "type": "string" }, "message": { "type": "string" } } } } } }, "SoundscapeNoiseGeneratorInput": { "type": "object", "additionalProperties": false, "properties": { "type": { "title": "Noise colour", "type": "string", "enum": [ "white", "pink", "brown", "blue", "violet" ], "default": "pink" }, "duration": { "title": "Duration", "description": "Up to 120 seconds (stereo at 96 kHz: up to 60 seconds). The WAV file is kept on the server for about 2 hours so you can download it, then deleted.", "type": "number", "minimum": 0.1, "maximum": 120, "default": 10, "x-unit": "s" }, "sampleRate": { "title": "Sample rate", "type": "string", "enum": [ "8000", "16000", "22050", "32000", "44100", "48000", "96000" ], "default": "44100" }, "channels": { "title": "Channels", "type": "string", "enum": [ "stereo", "mono" ], "default": "stereo" }, "level": { "title": "Level (RMS)", "description": "Average level. It is lowered automatically if the peaks would clip.", "type": "number", "minimum": -60, "maximum": -6, "default": -18, "x-unit": "dBFS" }, "fadeIn": { "title": "Fade in", "description": "Ignored for seamless loops.", "type": "number", "minimum": 0, "maximum": 30, "default": 0.5, "x-unit": "s" }, "fadeOut": { "title": "Fade out", "description": "Ignored for seamless loops.", "type": "number", "minimum": 0, "maximum": 30, "default": 0.5, "x-unit": "s" }, "loop": { "title": "Seamless loop (the end flows into the start)", "type": "boolean", "default": false }, "encoding": { "title": "File format", "type": "string", "enum": [ "pcm16", "float32" ], "default": "pcm16" }, "seed": { "title": "Seed", "description": "Same seed and settings = the same file, byte for byte. Change it for a different noise.", "type": "string", "maxLength": 40, "default": "1" } }, "required": [] }, "SoundscapeNoiseGeneratorResult": { "type": "object", "additionalProperties": false, "required": [ "schemaVersion", "tool", "computedAt", "inputs", "summary", "result", "units", "assumptions", "sources", "warnings", "presentation", "links" ], "properties": { "schemaVersion": { "type": "string", "const": "1.0" }, "tool": { "type": "object", "additionalProperties": false, "required": [ "id", "name", "version" ], "properties": { "id": { "type": "string" }, "name": { "type": "string" }, "version": { "type": "string" } } }, "computedAt": { "type": "string", "format": "date-time" }, "inputs": { "type": "object", "description": "Normalised inputs actually used, including applied defaults." }, "summary": { "type": "string" }, "result": { "type": "object", "additionalProperties": false, "required": [ "noiseType", "sampleRate", "channels", "durationSeconds", "frames", "encoding", "seed", "loop", "expectedSlopeDbPerOctave", "levelReduced", "spectrum", "seam", "artifact" ], "properties": { "noiseType": { "type": "string", "enum": [ "white", "pink", "brown", "blue", "violet" ] }, "sampleRate": { "type": "integer" }, "channels": { "type": "integer" }, "durationSeconds": { "type": "number" }, "frames": { "type": "integer" }, "encoding": { "type": "string" }, "seed": { "type": "string" }, "loop": { "type": "boolean" }, "expectedSlopeDbPerOctave": { "type": "number", "description": "Nominal slope of the chosen colour." }, "levelReduced": { "type": "boolean", "description": "True when the requested RMS level would have clipped and the level was lowered." }, "spectrum": { "type": "object", "additionalProperties": false, "required": [ "centroidHz", "rolloffHz", "slopeDbPerOctave", "peaks", "rmsDb", "peakDb", "crestDb", "octaveBands" ], "properties": { "centroidHz": { "type": "number", "description": "Power-weighted mean frequency (spectral centroid)." }, "rolloffHz": { "type": "number", "description": "Frequency below which 85 % of the power lies." }, "slopeDbPerOctave": { "type": "number", "description": "Least-squares slope of the 1/3-octave power spectrum between 100 Hz and min(10 kHz, sample rate / 4)." }, "peaks": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "frequencyHz", "levelDb" ], "properties": { "frequencyHz": { "type": "number" }, "levelDb": { "type": "number" } } } }, "rmsDb": { "type": "number" }, "peakDb": { "type": "number" }, "crestDb": { "type": "number" }, "octaveBands": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "centerHz", "relativeDb" ], "properties": { "centerHz": { "type": "number" }, "relativeDb": { "type": "number" } } } } } }, "seam": { "type": [ "object", "null" ], "additionalProperties": false, "required": [ "seamJump", "maxInnerJump" ], "properties": { "seamJump": { "type": "number" }, "maxInnerJump": { "type": "number" } } }, "artifact": { "type": "object", "additionalProperties": false, "required": [ "artifactId", "filename", "mime", "bytes", "sha256", "path" ], "properties": { "artifactId": { "type": "string" }, "filename": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "sha256": { "type": "string" }, "path": { "type": "string", "description": "Download path on the same site (valid for about 2 hours)." } } } } }, "units": { "type": "object", "additionalProperties": { "type": "string" } }, "assumptions": { "type": "array", "items": { "type": "string" } }, "sources": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "title" ], "properties": { "title": { "type": "string" }, "url": { "type": "string" }, "publisher": { "type": "string" }, "retrievedAt": { "type": "string" }, "note": { "type": "string" } } } }, "warnings": { "type": "array", "items": { "type": "string" } }, "presentation": { "type": "array", "items": { "type": "object" }, "description": "Display blocks used by the human page (same data)." }, "links": { "type": "object", "additionalProperties": false, "required": [ "human", "api", "openapi", "methodology" ], "properties": { "human": { "type": "string", "format": "uri" }, "api": { "type": "string", "format": "uri" }, "openapi": { "type": "string", "format": "uri" }, "methodology": { "type": "string", "format": "uri" } } } } } } } }