Fix overflow in audio code

src/audio/AudioManager.cpp

@@ -977,7 +977,7 @@ void
 cAudioManager::AdjustSamplesVolume()
 {
 	for (int i = 0; i < m_SampleRequestQueuesStatus[m_nActiveSampleQueue]; i++) {
-		tSound *pSample = &m_asSamples[m_nActiveSampleQueue][m_abSampleQueueIndexTable[m_nActiveSampleQueue][i] + 1];
+		tSound *pSample = &m_asSamples[m_nActiveSampleQueue][m_abSampleQueueIndexTable[m_nActiveSampleQueue][i]];
 
 		if (!pSample->m_bIs2D)
 			pSample->m_nEmittingVolume = ComputeEmittingVolume(pSample->m_nEmittingVolume, pSample->m_fSoundIntensity, pSample->m_fDistance);