C# + OpenTK.Audio.OpenAL sample

Program.cs

using OpenTK;
using OpenTK.Audio.OpenAL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication4 {
	class Program {
		static unsafe void Main(string[] args) {
			//Initialize
			var device = Alc.OpenDevice(null);
			var context = Alc.CreateContext(device, (int*)null);

			Alc.MakeContextCurrent(context);

			var version = AL.Get(ALGetString.Version);
			var vendor = AL.Get(ALGetString.Vendor);
			var renderer = AL.Get(ALGetString.Renderer);
			Console.WriteLine(version);
			Console.WriteLine(vendor);
			Console.WriteLine(renderer);
			Console.ReadKey();

			//Process
			int buffers, source;
			AL.GenBuffers(1, out buffers);
			AL.GenSources(1, out source);

			int sampleFreq = 44100;
			double dt = 2 * Math.PI / sampleFreq;
			double amp = 0.5;

			int freq = 440;
			var dataCount = sampleFreq / freq;

			var sinData = new short[dataCount];
			for (int i = 0; i < sinData.Length; ++i) {
				sinData[i] = (short)(amp * short.MaxValue * Math.Sin(i * dt * freq));
			}
			AL.BufferData(buffers, ALFormat.Mono16, sinData, sinData.Length, sampleFreq);
			AL.Source(source, ALSourcei.Buffer, buffers);
			AL.Source(source, ALSourceb.Looping, true);

			AL.SourcePlay(source);
			Console.ReadKey();

			///Dispose
			if (context != ContextHandle.Zero) {
				Alc.MakeContextCurrent(ContextHandle.Zero);
				Alc.DestroyContext(context);
			}
			context = ContextHandle.Zero;

			if (device != IntPtr.Zero) {
				Alc.CloseDevice(device);
			}
			device = IntPtr.Zero;
		}
	}
}

Program2.cs

using OpenTK;
using OpenTK.Audio.OpenAL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication4 {
	class Program {
		static unsafe void Main(string[] args) {
			//Initialize
			var device = Alc.OpenDevice(null);
			var context = Alc.CreateContext(device, (int*)null);

			Alc.MakeContextCurrent(context);

			var version = AL.Get(ALGetString.Version);
			var vendor = AL.Get(ALGetString.Vendor);
			var renderer = AL.Get(ALGetString.Renderer);
			Console.WriteLine(version);
			Console.WriteLine(vendor);
			Console.WriteLine(renderer);

			//Process

			int sampleFreq = 44100;
			double dt = 2 * Math.PI / sampleFreq;
			var dataCount = 100;
			double amp = 0.5;

			for (int freq = 440; freq < 10000; freq += 100) {
				int source;
				int buffers;
				AL.GenBuffers(1, out buffers);
				AL.GenSources(1, out source);

				var sinData = new short[dataCount];
				for (int i = 0; 
				i < sinData.Length; ++i) {
					sinData[i] = (short)(amp * short.MaxValue * Math.Sin(i * dt * freq));
				}

				AL.BufferData(buffers, ALFormat.Mono16, sinData, sinData.Length, sampleFreq);
				AL.Source(source, ALSourcei.Buffer, buffers);
				AL.Source(source, ALSourceb.Looping, true);

				AL.SourcePlay(source);
				Thread.Sleep(100);
			}
			Console.WriteLine("fin");
			Console.ReadKey();

			///Dispose
			if (context != ContextHandle.Zero) {
				Alc.MakeContextCurrent(ContextHandle.Zero);
				Alc.DestroyContext(context);
			}
			context = ContextHandle.Zero;

			if (device != IntPtr.Zero) {
				Alc.CloseDevice(device);
			}
			device = IntPtr.Zero;
		}
	}
}

The size parameter to AL.BufferData is in bytes, not samples, so

AL.BufferData(buffers, ALFormat.Mono16, sinData, sinData.Length, sampleFreq);

Should be

AL.BufferData(buffers, ALFormat.Mono16, sinData, sinData.Length * sizeof(short), sampleFreq);