diff --git a/source/SoundTouch/TDStretch.cpp b/source/SoundTouch/TDStretch.cpp
index ddfd2f7..f6bb0b5 100644
--- a/source/SoundTouch/TDStretch.cpp
+++ b/source/SoundTouch/TDStretch.cpp
@@ -123,15 +123,11 @@ TDStretch::~TDStretch()
 void TDStretch::setParameters(int aSampleRate, int aSequenceMS, 
                               int aSeekWindowMS, int aOverlapMS)
 {
-    assert(aSampleRate >= 0);
-    assert(aSequenceMS >= 0);
-    assert(aSeekWindowMS >= 0);
-    assert(aOverlapMS >= 0);
-
-    this->sampleRate = aSampleRate;
-    this->sequenceMs = aSequenceMS;
-    this->seekWindowMs = aSeekWindowMS;
-    this->overlapMs = aOverlapMS;
+    // accept only positive parameter values - if negative, use old values instead
+    if (aSampleRate >= 0)   this->sampleRate = aSampleRate;
+    if (aSequenceMS >= 0)   this->sequenceMs = aSequenceMS;
+    if (aSeekWindowMS >= 0) this->seekWindowMs = aSeekWindowMS;
+    if (aOverlapMS >= 0)    this->overlapMs = aOverlapMS;
 
     seekLength = (sampleRate * seekWindowMs) / 1000;
     seekWindowLength = (sampleRate * sequenceMs) / 1000;
@@ -867,7 +863,7 @@ void TDStretch::precalcCorrReferenceMono()
 }
 
 
-// SSE-optimized version of the function overlapStereo
+// Overlaps samples in 'midBuffer' with the samples in 'pInput'
 void TDStretch::overlapStereo(float *pOutput, const float *pInput) const
 {
     int i;
diff --git a/source/SoundTouch/TDStretch.h b/source/SoundTouch/TDStretch.h
index 09e0c5d..af29ac6 100644
--- a/source/SoundTouch/TDStretch.h
+++ b/source/SoundTouch/TDStretch.h
@@ -192,10 +192,10 @@ public:
     /// 'seekwindowMS' = seeking window length for scanning the best overlapping 
     ///      position
     /// 'overlapMS' = overlapping length
-    void setParameters(int sampleRate,                             ///< Samplerate of sound being processed (Hz)
-                       int sequenceMS = DEFAULT_SEQUENCE_MS,       ///< Single processing sequence length (ms)
-                       int seekwindowMS = DEFAULT_SEEKWINDOW_MS,   ///< Offset seeking window length (ms)
-                       int overlapMS = DEFAULT_OVERLAP_MS          ///< Sequence overlapping length (ms)
+    void setParameters(int sampleRate,          ///< Samplerate of sound being processed (Hz)
+                       int sequenceMS = -1,     ///< Single processing sequence length (ms)
+                       int seekwindowMS = -1,   ///< Offset seeking window length (ms)
+                       int overlapMS = -1       ///< Sequence overlapping length (ms)
                        );
 
     /// Get routine control parameters, see setParameters() function.