Hello to all,

I want to generate a wave file with a sweeping sine for example from 1000 Hz to 1200 Hz in 0.3 seconds increasing with 1 Hz steps.

For this I thought that I have to have always a full phase (returning to zero) before I can change the fequency to the next higher step. But I hear an artifact in the sweeping sine tone so that the tone is not completely smooth. In one phase I do calculate nearly the full phase (full phase - 1 sample) and the next higher frequency begins again with zero.

I use two functions:

(1) calculate a number of equal frequency phases (these are smooth without artifacts)

```
Function mdGenWavDataXperiods(aFrequency as Integer, aNumOfPeriods as integer) As MemoryBlock
// self.sampleRate As integer = 44100 Hertz
dim wavSampleCount As integer = ((self.sampleRate / aFrequency) * aNumOfPeriods) //generating of one period for a given frequency
dim m As new MemoryBlock(wavSampleCount)
// self.twoPi As double = 6.28318
dim timeScale As double = (self.twoPi / self.sampleRate)
dim lastSample As integer = wavSampleCount - 1
dim t As double
dim sinVol as integer = 127
for i As integer = 0 to lastSample
t = i * timeScale
m.UInt8Value(i) = 127 + sinVol * sin(aFrequency * t) // sine
next
return m
End Function
```

(2) in the next function I add different frequencies one after the other

```
Function mdGenGlideWavDataTEST() As MemoryBlock
dim mbArr() as MemoryBlock
for iFreq as integer = 1000 to 1200
mbArr.Append( self.mdGenWavDataXperiods(iFreq, 2) )
next iFreq
// calc total size for mbArr
dim mbArrSize As integer
for i as integer = 0 to mbArr.Ubound
mbArrSize = mbArrSize + mbArr(i).Size
next i
// copy the different MemoryBlocks into one MemoryBlock 'm'
dim m as new MemoryBlock(mbArrSize)
dim iSampleCounter as integer = 0
for i as integer = 0 to mbArr.Ubound
for j as integer = 0 to mbArr(i).Size - 1
m.Int8Value(iSampleCounter) = mbArr(i).Int8Value(j)
iSampleCounter = iSampleCounter + 1
next j
next i
return m
End Function
```

and then I add the WAV file header

```
Function createGlidingToneTEST(aToneFreqStart as integer, aToneFreqDifference as integer, aToneDuration as double) As String
if self.sound <> nil and self.sound.IsPlaying then
self.sound.stop
end if
dim firstToneFreq, secondToneFreq as integer
dim waveDataGliding As MemoryBlock = mdGenGlideWavDataTEST()
dim fileDataGliding As MemoryBlock = mdCreateWavFileData(waveDataGliding)
dim filenameStr as String = "sine_glide_" + Str(firstToneFreq) + "_" + Str(aToneFreqDifference) + "_" + Str(self.filenum) + ".wav"
#if DebugBuild and TargetWindows then
self.wavFile = GetFolderItem("").Parent.Child("stim").Child( filenameStr )
#else
self.wavFile = GetFolderItem("").Child("stim").Child( filenameStr )
#endif
dim bs As BinaryStream = BinaryStream.Create(self.wavFile, true)
bs.Write(fileDataGliding)
bs.Close
Return ""
End Function
```

Does anyone see the problem that could be the reason for an artifact or does anyone have a suitable code for sweep tone generation?

Any help is appreciated.

Thank you.

Thomas