Modify the gain after filtering to prevent TTS clipping in en-US.
diff --git a/packages/TtsService/jni/android_tts_SynthProxy.cpp b/packages/TtsService/jni/android_tts_SynthProxy.cpp
index 071a90d..0ec8dab 100644
--- a/packages/TtsService/jni/android_tts_SynthProxy.cpp
+++ b/packages/TtsService/jni/android_tts_SynthProxy.cpp
@@ -41,7 +41,7 @@
#define FILTER_LOWSHELF_ATTENUATION -18.0f // in dB
#define FILTER_TRANSITION_FREQ 1100.0f // in Hz
#define FILTER_SHELF_SLOPE 1.0f // Q
-#define FILTER_GAIN 6.0f // linear gain
+#define FILTER_GAIN 5.5f // linear gain
// such a huge gain is justified by how much energy in the low frequencies is "wasted" at the output
// of the synthesis. The low shelving filter removes it, leaving room for amplification.