听力补偿新增左右耳曲线

2026-07-14 14:30:55 +08:00
parent bfc4b45ca3
commit 4f3427b44f
9 changed files with 319 additions and 6 deletions
@@ -0,0 +1,112 @@
+/** Hearing compensation curve helpers: map levels → dB and cubic-spline smooth. */
+
+export const HEARING_FREQ_LABELS = ["125", "250", "500", "1k", "2k", "4k", "8k"] as const;
+
+/** Y = n + (-70). Values outside [-80, 0] are kept as-is (axis still -80…0). */
+export function mapHearingLevelToDb(n: number): number {
+  return n - 70;
+}
+
+/**
+ * Natural cubic spline for monotonically spaced `xs`.
+ * Returns an interpolator defined on [xs[0], xs[n-1]] (extrapolates flat at ends).
+ */
+export function createNaturalCubicSpline(
+  xs: number[],
+  ys: number[],
+): (x: number) => number {
+  const n = xs.length;
+  if (n === 0) return () => 0;
+  if (n === 1) return () => ys[0]!;
+  if (n === 2) {
+    const x0 = xs[0]!;
+    const x1 = xs[1]!;
+    const y0 = ys[0]!;
+    const y1 = ys[1]!;
+    return (x: number) => {
+      if (x1 === x0) return y0;
+      const t = (x - x0) / (x1 - x0);
+      return y0 + t * (y1 - y0);
+    };
+  }
+
+  const h = new Array<number>(n - 1);
+  for (let i = 0; i < n - 1; i++) h[i] = xs[i + 1]! - xs[i]!;
+
+  const alpha = new Array<number>(n).fill(0);
+  for (let i = 1; i < n - 1; i++) {
+    alpha[i] =
+      (3 / h[i]!) * (ys[i + 1]! - ys[i]!) -
+      (3 / h[i - 1]!) * (ys[i]! - ys[i - 1]!);
+  }
+
+  const l = new Array<number>(n).fill(1);
+  const mu = new Array<number>(n).fill(0);
+  const z = new Array<number>(n).fill(0);
+
+  for (let i = 1; i < n - 1; i++) {
+    l[i] = 2 * (xs[i + 1]! - xs[i - 1]!) - h[i - 1]! * mu[i - 1]!;
+    mu[i] = h[i]! / l[i]!;
+    z[i] = (alpha[i]! - h[i - 1]! * z[i - 1]!) / l[i]!;
+  }
+
+  const c = new Array<number>(n).fill(0);
+  const b = new Array<number>(n - 1).fill(0);
+  const d = new Array<number>(n - 1).fill(0);
+
+  for (let j = n - 2; j >= 0; j--) {
+    c[j] = z[j]! - mu[j]! * c[j + 1]!;
+    b[j] =
+      (ys[j + 1]! - ys[j]!) / h[j]! -
+      (h[j]! * (c[j + 1]! + 2 * c[j]!)) / 3;
+    d[j] = (c[j + 1]! - c[j]!) / (3 * h[j]!);
+  }
+
+  return (x: number) => {
+    let i = 0;
+    if (x <= xs[0]!) {
+      i = 0;
+    } else if (x >= xs[n - 1]!) {
+      i = n - 2;
+    } else {
+      let lo = 0;
+      let hi = n - 2;
+      while (lo <= hi) {
+        const mid = (lo + hi) >> 1;
+        if (x < xs[mid]!) {
+          hi = mid - 1;
+        } else if (x > xs[mid + 1]!) {
+          lo = mid + 1;
+        } else {
+          i = mid;
+          break;
+        }
+      }
+      if (x > xs[i + 1]!) i = Math.min(n - 2, lo);
+    }
+
+    const dx = x - xs[i]!;
+    return ys[i]! + b[i]! * dx + c[i]! * dx * dx + d[i]! * dx * dx * dx;
+  };
+}
+
+/**
+ * Build densely sampled [xIndex, dB] pairs for a smooth ECharts line.
+ * X uses equal spacing 0…6 matching HEARING_FREQ_LABELS.
+ */
+export function buildHearingSplineSeries(
+  levels: number[],
+  samplesPerSegment = 16,
+): [number, number][] {
+  const xs = levels.map((_, i) => i);
+  const ys = levels.map(mapHearingLevelToDb);
+  const spline = createNaturalCubicSpline(xs, ys);
+  const maxX = xs[xs.length - 1] ?? 0;
+  const steps = Math.max(1, maxX * samplesPerSegment);
+  const points: [number, number][] = [];
+  for (let s = 0; s <= steps; s++) {
+    const x = (s / steps) * maxX;
+    points.push([x, spline(x)]);
+  }
+  return points;
+}