MLECO-2723: Updating RNNoise to use 512 frame size

* CMSIS-DSP acceleration will now be used for FFT in RNNoise pre-processing
* PESQ scores tested and similar

Signed-off-by: Richard Burton <richard.burton@arm.com>
Change-Id: Ifeebc041f58867909b27c948950e08f8f39ef276
diff --git a/source/use_case/noise_reduction/src/MainLoop.cc b/source/use_case/noise_reduction/src/MainLoop.cc
index ee0a61b..7d814a8 100644
--- a/source/use_case/noise_reduction/src/MainLoop.cc
+++ b/source/use_case/noise_reduction/src/MainLoop.cc
@@ -106,6 +106,7 @@
                 break;
             case MENU_OPT_RUN_INF_CHOSEN: {
                 printf("    Enter the audio clip IFM index [0, %d]: ", NUMBER_OF_FILES-1);
+                fflush(stdout);
                 auto clipIndex = static_cast<uint32_t>(arm::app::ReadUserInputAsInt(platform));
                 SetAppCtxClipIdx(caseContext, clipIndex);
                 executionSuccessful = NoiseReductionHandler(caseContext, false);