diff --git a/twiml/voice_response.go b/twiml/voice_response.go
index 81c4de057..f33e0a01e 100644
--- a/twiml/voice_response.go
+++ b/twiml/voice_response.go
@@ -386,7 +386,7 @@ type VoiceW struct {
 }
 
 func (m VoiceW) GetName() string {
-	return "W"
+	return "w"
 }
 
 func (m VoiceW) GetText() string {
@@ -416,7 +416,7 @@ type VoiceSub struct {
 }
 
 func (m VoiceSub) GetName() string {
-	return "Sub"
+	return "sub"
 }
 
 func (m VoiceSub) GetText() string {
@@ -448,7 +448,7 @@ type VoiceSayAs struct {
 }
 
 func (m VoiceSayAs) GetName() string {
-	return "SayAs"
+	return "say-as"
 }
 
 func (m VoiceSayAs) GetText() string {
@@ -483,7 +483,7 @@ type VoiceProsody struct {
 }
 
 func (m VoiceProsody) GetName() string {
-	return "Prosody"
+	return "prosody"
 }
 
 func (m VoiceProsody) GetText() string {
@@ -513,7 +513,7 @@ type VoiceS struct {
 }
 
 func (m VoiceS) GetName() string {
-	return "S"
+	return "s"
 }
 
 func (m VoiceS) GetText() string {
@@ -542,7 +542,7 @@ type VoicePhoneme struct {
 }
 
 func (m VoicePhoneme) GetName() string {
-	return "Phoneme"
+	return "phoneme"
 }
 
 func (m VoicePhoneme) GetText() string {
@@ -573,7 +573,7 @@ type VoiceLang struct {
 }
 
 func (m VoiceLang) GetName() string {
-	return "Lang"
+	return "lang"
 }
 
 func (m VoiceLang) GetText() string {
@@ -601,7 +601,7 @@ type VoiceP struct {
 }
 
 func (m VoiceP) GetName() string {
-	return "P"
+	return "p"
 }
 
 func (m VoiceP) GetText() string {
@@ -628,7 +628,7 @@ type VoiceEmphasis struct {
 }
 
 func (m VoiceEmphasis) GetName() string {
-	return "Emphasis"
+	return "emphasis"
 }
 
 func (m VoiceEmphasis) GetText() string {
@@ -658,7 +658,7 @@ type VoiceBreak struct {
 }
 
 func (m VoiceBreak) GetName() string {
-	return "Break"
+	return "break"
 }
 
 func (m VoiceBreak) GetText() string {