Recipe catalog / passage-difficulty

Grade the difficulty of a musical passage

How hard is the passage described in passage for a player of instrument, from beginner to virtuoso?

You are building a practice app, lesson planner, or repertoire search and need to grade described passages or pieces so they can be matched to a player's level.

Explore this recipe interactively · Source and implementation guide

Use passage-difficulty in TypeScript

Install with npm install jev-recipes. Requires Node.js 22.9 or newer and ES modules. Set TYPESAFE_API_KEY in your server environment for live calls, which send input to TypeSafe and use API quota. See the installation guide.

import { passageDifficulty } from 'jev-recipes/passage-difficulty';

const result = await passageDifficulty({
  "passage": "Continuous sixteenth-note arpeggios across all four strings at quarter note = 144, in E-flat major, moving from first position up to seventh position and back every two bars, with string crossings on every beat and a two-octave leap into the final bar.",
  "instrument": "violin",
  "minConfidence": 0.8
});
console.log(result);

Input contract

{
  "input": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "passage": {
        "type": "string"
      },
      "instrument": {
        "type": "string"
      },
      "minConfidence": {
        "type": "number",
        "minimum": 0,
        "maximum": 1
      }
    },
    "required": [
      "passage"
    ]
  },
  "result": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "model": {
        "type": "string"
      },
      "usage": {
        "type": "object",
        "properties": {
          "input_tokens": {
            "type": "integer",
            "minimum": 0,
            "maximum": 9007199254740991
          },
          "output_tokens": {
            "type": "integer",
            "minimum": 0,
            "maximum": 9007199254740991
          }
        },
        "required": [
          "input_tokens",
          "output_tokens"
        ],
        "additionalProperties": false
      },
      "status": {
        "type": "string",
        "enum": [
          "ready",
          "review"
        ]
      },
      "score": {
        "type": "number",
        "minimum": 0
      },
      "level": {
        "type": "integer",
        "minimum": 0,
        "maximum": 9007199254740991
      },
      "confidence": {
        "type": "number",
        "minimum": 0,
        "maximum": 1
      },
      "probabilities": {
        "type": "object",
        "propertyNames": {
          "type": "string"
        },
        "additionalProperties": {
          "type": "number",
          "minimum": 0,
          "maximum": 1
        }
      },
      "difficulty": {
        "type": "string",
        "enum": [
          "beginner",
          "easy",
          "intermediate",
          "advanced",
          "virtuoso"
        ]
      }
    },
    "required": [
      "model",
      "usage",
      "status",
      "score",
      "level",
      "confidence",
      "probabilities",
      "difficulty"
    ],
    "additionalProperties": false
  }
}

Saved example result

This hand-authored response demonstrates the contract. It is not a model accuracy measurement. Run it without an API key: npx jev-recipes demo passage-difficulty.

{
  "model": "demo-fixture",
  "usage": {
    "input_tokens": 0,
    "output_tokens": 0
  },
  "status": "ready",
  "score": 2.95,
  "level": 3,
  "confidence": 0.84,
  "probabilities": {
    "0": 0,
    "1": 0.01,
    "2": 0.09,
    "3": 0.84,
    "4": 0.06
  },
  "difficulty": "advanced"
}

Evaluation evidence

Use the evaluation guide to measure this decision on your own labeled cases.

Limitations

• Grades the passage as described in text, not from a score or recording. Tempo, key, range, and technique count only when the description states them.
• Difficulty is relative to typical players of the named instrument; when instrument is omitted the grade assumes whatever instrument the description implies.
• Does not know a particular student's level. Matching a grade to a player belongs in application code.

Related recipes

• task-complexity: Use task-complexity to grade how involved a general task is, rather than how hard a musical passage is to play.
• audience-fit: Use audience-fit to check whether content suits a described audience, rather than to place a passage on a difficulty scale.