如何针对声卡编程发出特定频率的声音

Question

恩我想针对声卡或者主板蜂鸣器编程，2种方案：
1、针对声卡编程，使声卡发出特定频率的声音，c语言，或者vb 汇编都可以，不知各位大大谁能给个源代码或者重要的提示。

2、针对主板蜂鸣器编程，使蜂鸣器发出超声波，任何语言编的都可以，给个源代码或者重要的提示。
两种都可以，当然哪位大大能2种都给出来俺一定感激不尽，狂给你分的

Answer 1

蜂鸣器编程的话，有个API函数，VB中的声明为
Declare Function Beep Lib "kernel32" Alias "Beep" (ByVal dwFreq As Long, ByVal dwDuration As Long) As Long

调用方法是Beep 声音频率,持续时间（毫秒为单位）
比如 beep 2000,1000

如果是声卡编程的话，也有相应的API函数，比如你可以用DirectSound(也就是DirectX的一部分)，功能比较强大，也很专业。事实上，如果你使用的是专业级的声卡和音响设备，它可以在一定范围内回放出超出人耳听觉范围的声音。当然也可以用简单一点的API，以下是几个需要的函数：
Private Declare Function midiOutGetDevCaps Lib "winmm.dll" Alias "midiOutGetDevCapsA" (ByVal uDeviceID As Long, lpCaps As MIDIOUTCAPS, ByVal uSize As Long) As Long
Private Declare Function midiOutGetNumDevs Lib "winmm" () As Integer
Private Declare Function MIDIOutOpen Lib "winmm.dll" Alias "midiOutOpen" (lphMidiOut As Long, ByVal uDeviceID As Long, ByVal dwCallback As Long, ByVal dwInstance As Long, ByVal dwFlags As Long) As Long
Private Declare Function midiOutClose Lib "winmm.dll" (ByVal hMidiOut As Long) As Long
Private Declare Function midiOutShortMsg Lib "winmm.dll" (ByVal hMidiOut As Long, ByVal dwMsg As Long) As Long
Private Declare Function midiOutGetErrorText Lib "winmm.dll" Alias "midiOutGetErrorTextA" (ByVal err As Long, ByVal lpText As String, ByVal uSize As Long) As Long

Private Const MAXERRORLENGTH = 128 ' max error text length (including NULL)

Private Const MIDIMAPPER = (-1)
Private Const MIDI_MAPPER = (-1)
'MIDIOUTCAPS结构描述了Musical Instrument Digital Interface(MIDI)输入设备的性能
Type MIDIOUTCAPS
wMid As Integer
wPid As Integer ' 产品 ID
vDriverVersion As Long ' 设备版本
szPname As String * 32 ' 设备 name
wTechnology As Integer ' 设备类型
wVoices As Integer
wNotes As Integer
wChannelMask As Integer
dwSupport As Long
End Type

Public Sub note_on(ch As Integer, ByVal kk As Integer, v As Integer)
' 发音主函数。参数分别为通道编号，音调，速度
Call midi_outshort(&H90 + ch, kk, v)
End Sub

Sub midi_outshort(b1 As Integer, b2 As Integer, b3 As Integer)
Dim midi_error As Integer

midi_error = midiOutShortMsg(hMidi, b3 * &H10000 + b2 * &H100 + b1)
If Not midi_error = 0 Then
Call midi_outerr(midi_error)
End If
End Sub

Sub midi_outerr(ByVal midi_error As Integer)
Dim s As String
Dim x As Integer

s = Space(MAXERRORLENGTH)
x = midiOutGetErrorText(midi_error, s, MAXERRORLENGTH)
MsgBox s

End Sub

Answer 2

曾经有过这样的程序，像电子蚊香之类的，用编程实现次声波
但是，后来这种理论就被推翻了~
原因是由于硬件的局限性，声卡或则主板蜂鸣器的发声范围在硬件制造时已经限制过了
绝对发不出超声波或则次声波~