From c661ac7ccea4a4cf0b9d994f6c973d2330106939 Mon Sep 17 00:00:00 2001
From: Eric Rosenbaum <eric.rosenbaum@gmail.com>
Date: Thu, 1 Feb 2018 19:53:41 -0500
Subject: [PATCH] Only measure loudness once per step

---
 src/blocks/scratch3_sensing.js | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/blocks/scratch3_sensing.js b/src/blocks/scratch3_sensing.js
index f7a39b6b9..acecc3733 100644
--- a/src/blocks/scratch3_sensing.js
+++ b/src/blocks/scratch3_sensing.js
@@ -1,4 +1,5 @@
 const Cast = require('../util/cast');
+const Timer = require('../util/timer');
 
 class Scratch3SensingBlocks {
     constructor (runtime) {
@@ -23,6 +24,8 @@ class Scratch3SensingBlocks {
         this.runtime.on('ANSWER', this._onAnswer.bind(this));
         this.runtime.on('PROJECT_START', this._resetAnswer.bind(this));
         this.runtime.on('PROJECT_STOP_ALL', this._clearAllQuestions.bind(this));
+
+        this.timer = new Timer();
     }
 
     /**
@@ -217,7 +220,19 @@ class Scratch3SensingBlocks {
 
     getLoudness () {
         if (typeof this.runtime.audioEngine === 'undefined') return -1;
-        return this.runtime.audioEngine.getLoudness();
+        if (typeof this.runtime.currentStepTime === 'undefined') return -1;
+
+        // Only measure loudness once per step
+        if (this.loudnessTime) {
+            const timeSinceLoudness = this.timer.time() - this.loudnessTime;
+            if (timeSinceLoudness < this.runtime.currentStepTime) {
+                return this.loudness;
+            }
+        }
+
+        this.loudnessTime = this.timer.time();
+        this.loudness = this.runtime.audioEngine.getLoudness();
+        return this.loudness;
     }
 
     getAttributeOf (args) {