Noise suppression tweaks.

noise/suppression_test.go

@@ -0,0 +1,103 @@
+package noise
+
+import (
+	"math"
+	"testing"
+)
+
+func TestSuppressorDisabledBypassesSamples(t *testing.T) {
+	suppressor := NewSuppressor()
+	samples := []int16{100, -200, 300, -400, 500}
+	original := append([]int16(nil), samples...)
+
+	suppressor.ProcessSamples(samples)
+
+	for i := range samples {
+		if samples[i] != original[i] {
+			t.Fatalf("expected sample %d to remain unchanged, got %d want %d", i, samples[i], original[i])
+		}
+	}
+}
+
+func TestSuppressorAttenuatesLowLevelNoise(t *testing.T) {
+	suppressor := NewSuppressor()
+	suppressor.SetEnabled(true)
+	suppressor.SetThreshold(0.08)
+
+	input := makeSineFrame(600, 700)
+	originalRMS := frameRMS(input)
+	processed := append([]int16(nil), input...)
+	suppressor.ProcessSamples(processed)
+	processedRMS := frameRMS(processed)
+
+	if processedRMS >= originalRMS*0.8 {
+		t.Fatalf("expected low-level noise attenuation, got RMS %.2f from %.2f", processedRMS, originalRMS)
+	}
+}
+
+func TestSuppressorPreservesSpeechLikeSignal(t *testing.T) {
+	suppressor := NewSuppressor()
+	suppressor.SetEnabled(true)
+	suppressor.SetThreshold(0.08)
+
+	voice := makeSineFrame(1000, 9000)
+	originalRMS := frameRMS(voice)
+	processed := append([]int16(nil), voice...)
+	suppressor.ProcessSamples(processed)
+	processedRMS := frameRMS(processed)
+
+	if processedRMS <= originalRMS*0.6 {
+		t.Fatalf("expected speech-like signal to be mostly preserved, got RMS %.2f from %.2f", processedRMS, originalRMS)
+	}
+}
+
+func TestHigherThresholdAppliesStrongerSuppression(t *testing.T) {
+	lowSuppressor := NewSuppressor()
+	lowSuppressor.SetEnabled(true)
+	lowSuppressor.SetThreshold(0.02)
+
+	highSuppressor := NewSuppressor()
+	highSuppressor.SetEnabled(true)
+	highSuppressor.SetThreshold(0.20)
+
+	noiseFrame := makeSineFrame(500, 700)
+	lowRMS := runFrameWarmup(lowSuppressor, noiseFrame, 8)
+	highRMS := runFrameWarmup(highSuppressor, noiseFrame, 8)
+
+	if highRMS >= lowRMS*0.8 {
+		t.Fatalf("expected stronger suppression at higher threshold, got low %.2f high %.2f", lowRMS, highRMS)
+	}
+}
+
+func runFrameWarmup(suppressor *Suppressor, frame []int16, repeats int) float64 {
+	var processed []int16
+	for i := 0; i < repeats; i++ {
+		processed = append([]int16(nil), frame...)
+		suppressor.ProcessSamples(processed)
+	}
+	return frameRMS(processed)
+}
+
+func makeSineFrame(frequency float64, amplitude float64) []int16 {
+	const sampleRate = 48000.0
+	const frameSize = 480
+
+	frame := make([]int16, frameSize)
+	for i := 0; i < frameSize; i++ {
+		value := math.Sin((2.0 * math.Pi * frequency * float64(i)) / sampleRate)
+		frame[i] = int16(value * amplitude)
+	}
+	return frame
+}
+
+func frameRMS(samples []int16) float64 {
+	if len(samples) == 0 {
+		return 0.0
+	}
+	var sumSquares float64
+	for _, sample := range samples {
+		normalized := float64(sample) / 32768.0
+		sumSquares += normalized * normalized
+	}
+	return math.Sqrt(sumSquares / float64(len(samples)))
+}