commit 5f01999726b606c038fa1cd38df421a8ba10baee
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Sat Jun 30 15:43:56 2018 +0200

    Make empty voice name select the default voice
    
    See http://bugs.debian.org/872194
    This fixes #11.

diff --git a/espeak.c b/espeak.c
index 5fd9342..8871d1b 100644
--- a/espeak.c
+++ b/espeak.c
@@ -311,7 +311,7 @@ int initialize_espeak(struct synth_t *s)
 		espeak_SetSynthCallback(acsint_callback);
 
 	/* Setup initial voice parameters */
-	if (defaultVoice) {
+	if (defaultVoice && defaultVoice[0]) {
 		set_voice(s, defaultVoice);
 		free(defaultVoice);
 		defaultVoice = NULL;