Treating schwa as a separate phone

src/Phone.cpp

@@ -22,6 +22,7 @@ EnumConverter<Phone>::member_data PhoneConverter::getMemberData() {
 		{ Phone::IH,		"IH" },
 		{ Phone::UH,		"UH" },
 		{ Phone::AH,		"AH" },
+		{ Phone::Schwa,		"Schwa" },
 		{ Phone::AE,		"AE" },
 		{ Phone::EY,		"EY" },
 		{ Phone::AY,		"AY" },

src/Phone.h

@@ -15,7 +15,8 @@ enum class Phone {
 	EH,		// [ɛ] as in r[e]d, m[e]n
 	IH,		// [ɪ] as in b[i]g, w[i]n
 	UH,		// [ʊ] as in sh[ou]ld, c[ou]ld
-	AH,		// [ʌ, ə] as in b[u]t, s[u]n, [a]lone, disc[u]s
+	AH,		// [ʌ] as in b[u]t, s[u]n
+	Schwa,	// [ə] as in [a]lone, disc[u]s
 	AE,		// [æ] as in [a]t, b[a]t
 
 	// ... diphthongs

src/mouthAnimation.cpp

@@ -60,7 +60,8 @@ Timeline<Viseme> animate(optional<Phone> phone, centiseconds duration, centiseco
 	case Phone::EH:			return single({ { C }, 20_cs, { D } });
 	case Phone::IH:			return single({ B });
 	case Phone::UH:			return single({ E });
-	case Phone::AH:			return single({ { B, C, D, E, F }, 6_cs, { C } }); // Heuristic: < 6_cs is schwa
+	case Phone::AH:			return single({ C }); 
+	case Phone::Schwa:		return single({ { B, C, D, E, F } }); 
 	case Phone::AE:			return single({ D });
 	case Phone::EY:			return diphtong({ { C }, 20_cs, { D } }, { B });
 	case Phone::AY:			return diphtong({ D }, { B });

src/phoneRecognition.cpp

@@ -203,7 +203,12 @@ optional<Timeline<Phone>> getPhoneAlignment(
 		// Add entry
 		centiseconds start(phoneEntry->start);
 		centiseconds duration(phoneEntry->duration);
-		Timed<Phone> timedPhone(start, start + duration, PhoneConverter::get().parse(phoneName));
+		Phone phone = PhoneConverter::get().parse(phoneName);
+		if (phone == Phone::AH && duration < 6_cs) {
+			// Heuristic: < 6_cs is schwa. Pocketsphinx doesn't differentiate.
+			phone = Phone::Schwa;
+		}
+		Timed<Phone> timedPhone(start, start + duration, phone);
 		result.set(timedPhone);
 	}
 	return result;