Here also no anti-phase addition of signals of the same frequency / shape ...
Sub Globals
'These global variables will be redeclared each time the activity is created.
Dim NumGenerators As Int = 3 'in for a penny, in for a pound
Dim NumChannels As Int = 2 'left = 0, right = 1
Dim Frequency(NumGenerators) As Float 'Hz
Dim Level(NumGenerators, NumChannels) As Int '0 to 100%
Dim Phase(NumGenerators, NumChannels) As Float '0 to 360 degrees
Dim PhaseAccumulator(NumGenerators) As Int 'binary fixed-point 16.16
Dim PhaseIncrement(NumGenerators) As Int 'binary fixed-point 16.16
Dim PhaseShift(NumGenerators, NumChannels) As Int 'binary fixed-point 16.16
Dim WaveTableSize As Int = 256 'power of 2
Dim WaveTableIndexMask As Int = WaveTableSize - 1 '0b11111111
Dim WaveTables(NumGenerators) As Object 'pretty sure that Android audio uses signed 16-bit samples
Dim SampleRate As Int = 44100 '30 frames/second x 490 lines/frame x 3 samples/line
Dim Streamer As AudioStreamer
End SubSub MakeSineWaveTable(NumSamples As Int) As Short()
Dim S(NumSamples) As Short
For I = 0 To NumSamples - 1
Dim Angle As Float = I * 2 * cPI / NumSamples
Dim Sample As Float = Sin(Angle) * 32768
If Sample < -32768 Then
Sample = -32768
else if Sample > 32767 Then
Sample = 32767
End If
S(I) = Sample
Next
Return S
End SubSub UpdateGeneratorParameters(Generator As Int)
PhaseIncrement(Generator) = FrequencyToPhaseIncrement(Frequency(Generator))
For C = 0 To NumChannels - 1
PhaseShift(Generator, C) = PhaseToPhaseShift(Phase(Generator, C))
Next
End Sub
Sub FrequencyToPhaseIncrement(Hertz As Float) As Int
Return Hertz / SampleRate * WaveTableSize * 0x10000 + 0.5 'amount to increment phase accumulator by each sample time
End Sub
Sub PhaseToPhaseShift(Degrees As Float) As Int
Return Degrees / 360 * WaveTableSize * 0x10000 + 0.5
End SubSub GenerateSamples(NumSamples As Int) As Short()
Dim S(NumChannels * NumSamples) As Short
Dim SP As Int = 0
Dim TotalChannelSample(NumChannels) As Int
For I = 1 To NumSamples
For C = 0 To NumChannels - 1
TotalChannelSample(C) = 0
Next
For G = 0 To NumGenerators - 1
Dim WaveTable() As Short = WaveTables(G) 'cast from object wtf
PhaseAccumulator(G) = Bit.And(PhaseAccumulator(G) + PhaseIncrement(G), 0x3FFFFFFF) 'clear high two bits to avoid Int overflow
For C = 0 To NumChannels - 1
Dim WaveTableIndex As Int = Bit.ShiftRight(PhaseAccumulator(G) + PhaseShift(G, C), 16)
Dim WaveSample As Int = WaveTable(Bit.And(WaveTableIndex, WaveTableIndexMask))
Dim ChannelSample As Int = (WaveSample * Level(G, C) + 50) / 100
TotalChannelSample(C) = TotalChannelSample(C) + ChannelSample
Next
Next
For C = 0 To NumChannels - 1
Dim Temp As Int = TotalChannelSample(C)
If Temp < -32768 Then
Temp = -32768
else if Temp > 32767 Then
Temp = 32767
End If
S(SP) = Temp
SP = SP + 1 'interleaved channel eg 5.1 = 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5
Next
Next
Return S
End SubSub Activity_Create(FirstTime As Boolean)
WaveTables(0) = MakeSineWaveTable(WaveTableSize) 'could do in loop
WaveTables(1) = MakeSineWaveTable(WaveTableSize) 'but maybe one day might have
WaveTables(2) = MakeSineWaveTable(WaveTableSize) 'different waveform for each channel
'default Level and Phase parameters aka Captain Lazy Strikes Again
For G = 0 To NumGenerators - 1
For C = 0 To NumChannels - 1
Level(G, C) = 0
Phase(G, C) = 0
Next
Next
Frequency(0) = 440
Level(0, 0) = 30
Frequency(1) = 439
Level(1, 1) = 20
Frequency(2) = 438
Level(2, 0) = 10
For G = 0 To NumGenerators - 1
UpdateGeneratorParameters(G)
Next
Streamer.Initialize("streamer", 44100, False, 16, Streamer.VOLUME_MUSIC)
Streamer.StartPlaying
Dim bc As ByteConverter
bc.LittleEndian = True
For TenthOfSecond = 1 To 100 '10 seconds
Dim S() As Short = GenerateSamples(SampleRate / 10)
Log(Streamer.Write(bc.ShortsToBytes(S)))
Next
Streamer.Write(Null) 'when this "message" will be processed, the player will stop.
End SubAgreed, but i have just tested with my daughter (22 yr old):
You are right that seems the audio system especially the speaker has more impact than getting old. Literature shows getting old is more related to high freq loss.not by old ear
www.notebookcheck.net
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