diff --git a/src/blacksound/soundgenerator.cpp b/src/blacksound/soundgenerator.cpp
index 1ae6d6a30..853e97c61 100644
--- a/src/blacksound/soundgenerator.cpp
+++ b/src/blacksound/soundgenerator.cpp
@@ -80,10 +80,10 @@ namespace BlackSound
 
         foreach(Tone t, this->m_tones)
         {
-            qint64 lengthPerTone = this->m_audioFormat.sampleRate() * bytesForAllChannels * t.m_durationMs / 1000;
+            qint64 bytesPerTone = this->m_audioFormat.sampleRate() * bytesForAllChannels * t.m_durationMs / 1000;
             int sampleIndexPerTone = 0;
 
-            while (lengthPerTone)
+            while (bytesPerTone)
             {
                 // http://hyperphysics.phy-astr.gsu.edu/hbase/audio/sumdif.html
                 // http://math.stackexchange.com/questions/164369/how-do-you-calculate-the-frequency-perceived-by-humans-of-two-sinusoidal-waves-a
@@ -130,7 +130,7 @@ namespace BlackSound
                     }
 
                     bufferPointer += bytesPerSample;
-                    lengthPerTone -= bytesPerSample;
+                    bytesPerTone -= bytesPerSample;
                 }
                 ++sampleIndexPerTone;
             }
@@ -253,9 +253,10 @@ namespace BlackSound
         {
             QList<CFrequency> frequencies = selcal.getFrequencies();
             Q_ASSERT(frequencies.size() == 4);
-            Tone t1(frequencies.at(0).value(CFrequencyUnit::Hz()), frequencies.at(1).value(CFrequencyUnit::Hz()), 1000);
-            Tone t2(0, 200);
-            Tone t3(frequencies.at(2).value(CFrequencyUnit::Hz()), frequencies.at(3).value(CFrequencyUnit::Hz()), 1000);
+            const BlackMisc::PhysicalQuantities::CTime oneSec(1000.0, BlackMisc::PhysicalQuantities::CTimeUnit::ms());
+            Tone t1(frequencies.at(0), frequencies.at(1), oneSec);
+            Tone t2(CFrequency(), oneSec / 5.0);
+            Tone t3(frequencies.at(2), frequencies.at(3), oneSec);
             tones << t1 << t2 << t3;
         }
         return CSoundGenerator::playSignal(volume, tones, device);
diff --git a/src/blacksound/soundgenerator.h b/src/blacksound/soundgenerator.h
index c197e5f71..753aa76c8 100644
--- a/src/blacksound/soundgenerator.h
+++ b/src/blacksound/soundgenerator.h
@@ -8,6 +8,7 @@
 
 #include "blackmisc/avselcal.h"
 #include "blackmisc/vaudiodevice.h"
+#include "blackmisc/pqtime.h"
 
 #include <QIODevice>
 #include <QAudioFormat>
@@ -41,19 +42,29 @@ namespace BlackSound
          */
         struct Tone
         {
+            friend class CSoundGenerator;
+
+        private:
             int m_frequencyHz; /*!< first tone's frequency, use 0 for silence */
             int m_secondaryFrequencyHz; /*!< second tone's frequency, or 0 */
             qint64 m_durationMs; /*!< How long to play */
 
+        public:
             /*!
              * \brief Play frequency f for t milliseconds
              */
-            Tone(int frequencyHz, qint64 durationMs) : m_frequencyHz(frequencyHz), m_secondaryFrequencyHz(0), m_durationMs(durationMs) {}
+            Tone(const BlackMisc::PhysicalQuantities::CFrequency &frequency, const BlackMisc::PhysicalQuantities::CTime &duration) :
+                m_frequencyHz(static_cast<int>(frequency.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::Hz()))),
+                m_secondaryFrequencyHz(0),
+                m_durationMs(static_cast<qint64>(duration.valueRounded(BlackMisc::PhysicalQuantities::CTimeUnit::ms()))) {}
 
             /*!
              * \brief Play 2 frequencies f for t milliseconds
              */
-            Tone(int frequencyHz, int secondaryFrequencyHz, qint64 durationMs) : m_frequencyHz(frequencyHz), m_secondaryFrequencyHz(secondaryFrequencyHz), m_durationMs(durationMs) {}
+            Tone(const BlackMisc::PhysicalQuantities::CFrequency &frequency, const BlackMisc::PhysicalQuantities::CFrequency &secondaryFrequency, const BlackMisc::PhysicalQuantities::CTime &duration) :
+                m_frequencyHz(static_cast<int>(frequency.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::Hz()))),
+                m_secondaryFrequencyHz(static_cast<int>(secondaryFrequency.valueRounded(BlackMisc::PhysicalQuantities::CFrequencyUnit::Hz()))),
+                m_durationMs(static_cast<qint64>(duration.valueRounded(BlackMisc::PhysicalQuantities::CTimeUnit::ms()))) {}
         };
 
         /*!
@@ -185,9 +196,9 @@ namespace BlackSound
         /*!
          * \brief One cycle of tones takes t milliseconds
          */
-        qint64 oneCycleDurationMs() const
+        BlackMisc::PhysicalQuantities::CTime oneCycleDurationMs() const
         {
-            return this->m_oneCycleDurationMs;
+            return BlackMisc::PhysicalQuantities::CTime(this->m_oneCycleDurationMs, BlackMisc::PhysicalQuantities::CTimeUnit::ms());
         }
 
     signals: