diff --git a/internal/audio/audio_test.go b/internal/audio/audio_test.go
index fea8f2e..d010035 100644
--- a/internal/audio/audio_test.go
+++ b/internal/audio/audio_test.go
@@ -82,6 +82,38 @@ func TestWAVRoundTrip(t *testing.T) {
 	}
 }
 
+// A LIST chunk sitting between fmt and data is common (arecord and ffmpeg both
+// write one), and its payload is free text that can spell "data". The parser
+// walks chunk headers, so the text is skipped and the real samples are read.
+func TestPCMFromWAVSkipsLISTChunk(t *testing.T) {
+	t.Parallel()
+	pcm := []byte{1, 0, 2, 0, 3, 0, 4, 0}
+	list := []byte("LIST")
+	payload := []byte("INFOICMTdata is not here")
+	list = binary.LittleEndian.AppendUint32(list, uint32(len(payload)))
+	list = append(list, payload...)
+
+	plain, err := WAVFromPCM(PCM16kMono, pcm)
+	if err != nil {
+		t.Fatalf("WAVFromPCM: %v", err)
+	}
+	wav := append([]byte{}, plain[:36]...)
+	wav = append(wav, list...)
+	wav = append(wav, plain[36:]...)
+	binary.LittleEndian.PutUint32(wav[4:8], uint32(len(wav)-8))
+
+	f, got, err := PCMFromWAV(wav)
+	if err != nil {
+		t.Fatalf("PCMFromWAV: %v", err)
+	}
+	if !f.IsValid() {
+		t.Fatalf("parsed format invalid: %+v", f)
+	}
+	if !bytes.Equal(got, pcm) {
+		t.Fatalf("PCM mismatch: got %v, want %v", got, pcm)
+	}
+}
+
 func TestPCMFromWAVRejectsNonCanonical(t *testing.T) {
 	t.Parallel()
 	// too short
diff --git a/internal/audio/pcmwav.go b/internal/audio/pcmwav.go
index b9da0f8..27c58ae 100644
--- a/internal/audio/pcmwav.go
+++ b/internal/audio/pcmwav.go
@@ -36,6 +36,10 @@ const wavHeaderSize = 44
 // raw PCM samples (little-endian int16 as bytes). A non-canonical blob is
 // rejected with ErrNotCanonicalPCM; the format mismatch is logged at the seam
 // so the caller surfaces it, not a hidden silent downmix.
+//
+// The returned PCM aliases wav rather than copying it, because a recording is
+// large and the caller already owns the bytes. A caller that keeps the PCM past
+// the life of wav, or that reuses wav as a read buffer, must copy first.
 func PCMFromWAV(wav []byte) (Format, []byte, error) {
 	if len(wav) < wavHeaderSize {
 		return Format{}, nil, fmt.Errorf("audio: wav too short: %d bytes", len(wav))
@@ -61,17 +65,13 @@ func PCMFromWAV(wav []byte) (Format, []byte, error) {
 		return Format{}, nil, fmt.Errorf("%w: channels=%d bits=%d (want 1/16)", ErrNotCanonicalPCM, channels, bitsPerSample)
 	}
 	// data chunk: the spec mandates it appears right after fmt, but real
-	// recorders sometimes append extra chunks (LIST, fact). Find the "data"
-	// chunk by scanning; require it within the region we'd expect.
-	dataIdx := -1
-	for i := wavHeaderSize - 8; i+8 <= len(wav) && i < wavHeaderSize+4096; i++ {
-		if string(wav[i:i+4]) == "data" {
-			dataIdx = i
-			break
-		}
-	}
-	if dataIdx < 0 {
-		return Format{}, nil, fmt.Errorf("%w: no data chunk", ErrNotCanonicalPCM)
+	// recorders sometimes append extra chunks (LIST, fact). Walk the chunk
+	// headers rather than scanning for the four bytes "data", because those
+	// bytes occur inside a LIST/INFO payload as ordinary text and a byte scan
+	// would take the middle of a comment for a chunk header.
+	dataIdx, err := findDataChunk(wav)
+	if err != nil {
+		return Format{}, nil, err
 	}
 	dataSize := binary.LittleEndian.Uint32(wav[dataIdx+4 : dataIdx+8])
 	body := wav[dataIdx+8:]
@@ -90,6 +90,24 @@ func PCMFromWAV(wav []byte) (Format, []byte, error) {
 	return f, body, nil
 }
 
+// findDataChunk returns the offset of the "data" chunk header, walking the
+// chunk list that starts after the 16-byte fmt chunk. Chunks are word-aligned,
+// so an odd size carries one pad byte the next header sits behind.
+func findDataChunk(wav []byte) (int, error) {
+	for pos := wavHeaderSize - 8; pos+8 <= len(wav); {
+		size := int(binary.LittleEndian.Uint32(wav[pos+4 : pos+8]))
+		if string(wav[pos:pos+4]) == "data" {
+			return pos, nil
+		}
+		next := pos + 8 + size + size%2
+		if next <= pos || next > len(wav) {
+			break
+		}
+		pos = next
+	}
+	return 0, fmt.Errorf("%w: no data chunk", ErrNotCanonicalPCM)
+}
+
 // WAVFromPCM wraps raw 16-bit mono PCM bytes in a canonical 44-byte WAV
 // header so the result can be written to disk and played with `aplay`.
 // Used by the reference client to write the TTS reply; not on the wire.
@@ -115,7 +133,7 @@ const WAVHeaderSize = wavHeaderSize
 // avoiding.
 func WAVHeader(format Format, n int) ([]byte, error) {
 	if !format.IsValid() {
-		return nil, fmt.Errorf("audio: WAVFromPCM: %w: %+v", ErrNotCanonicalPCM, format)
+		return nil, fmt.Errorf("audio: WAVHeader: %w: %+v", ErrNotCanonicalPCM, format)
 	}
 	out := make([]byte, wavHeaderSize)
 	// RIFF header
diff --git a/internal/speaker/recognizer.go b/internal/speaker/recognizer.go
index d881de5..e8d8f6f 100644
--- a/internal/speaker/recognizer.go
+++ b/internal/speaker/recognizer.go
@@ -75,8 +75,8 @@ func (r *Recognizer) Identify(ctx context.Context, a audio.Audio) (Match, error)
 	if !a.Format.IsValid() {
 		return Match{}, fmt.Errorf("%w: %+v", ErrBadFormat, a.Format)
 	}
-	if seconds(a) < r.minSec {
-		return Match{}, fmt.Errorf("%w: %.1fs, need %.1fs", ErrTooShort, seconds(a), r.minSec)
+	if sec := seconds(a); sec < r.minSec {
+		return Match{}, fmt.Errorf("%w: %.1fs, need %.1fs", ErrTooShort, sec, r.minSec)
 	}
 	vec, err := r.embed(ctx, a)
 	if err != nil {
diff --git a/internal/tts/lexicon_test.go b/internal/tts/lexicon_test.go
index 8dbd175..65f6a46 100644
--- a/internal/tts/lexicon_test.go
+++ b/internal/tts/lexicon_test.go
@@ -23,6 +23,9 @@ func TestLexiconRewritesNames(t *testing.T) {
 		// Two names in a row share the space between them, which one pass
 		// would consume.
 		{"GPU GPU", "джи-пи-ю джи-пи-ю"},
+		// Two passes cover a run of any length, because the first pass takes
+		// every other name and leaves both boundaries of the ones it skipped.
+		{"GPU GPU GPU GPU", "джи-пи-ю джи-пи-ю джи-пи-ю джи-пи-ю"},
 		// Not a word boundary: a name inside a longer token is left alone.
 		{"vikunjaless", "vikunjaless"},
 		{"ничего не совпало", "ничего не совпало"},
diff --git a/internal/tts/tts.go b/internal/tts/tts.go
index 4fae0ab..0675aba 100644
--- a/internal/tts/tts.go
+++ b/internal/tts/tts.go
@@ -20,6 +20,7 @@ package tts
 
 import (
 	"context"
+	"encoding/binary"
 	"fmt"
 	"math"
 
@@ -50,17 +51,20 @@ func NewStub() *Stub { return &Stub{} }
 // silent no-op a bug could hide behind).
 func (s *Stub) Synthesize(_ context.Context, text string) (audio.Audio, error) {
 	const durMs = 200
-	const samples = 16000 * durMs / 1000 // 3200 samples @ 16k
-	pcm := make([]byte, samples*2)
+	// The rate is read off the canonical format rather than written again, so
+	// the tone stays in tune with the shape the seam declares.
+	rate := audio.PCM16kMono.SampleRate
+	bytesPerSample := audio.PCM16kMono.SampleBits / 8
+	samples := rate * durMs / 1000
+	pcm := make([]byte, samples*bytesPerSample)
 	freq := 220.0 // A3
 	if len(text) > 0 {
 		freq = 180.0 + float64(text[0]%6)*60 // 180..480 Hz band
 	}
 	for i := 0; i < samples; i++ {
-		t := float64(i) / 16000.0
+		t := float64(i) / float64(rate)
 		v := int16(12000 * math.Sin(2*math.Pi*freq*t))
-		pcm[i*2] = byte(v)
-		pcm[i*2+1] = byte(v >> 8)
+		binary.LittleEndian.PutUint16(pcm[i*2:], uint16(v))
 	}
 	return audio.Audio{Format: audio.PCM16kMono, Bytes: pcm}, nil
 }