语音已经切换，旧环境音为什么还能覆盖播放缓冲

enum CommitResult
{
    Applied,
    StaleRequest,
    WrongStream,
    WrongChannelCount,
    IncompleteBlock,
    NonFiniteSample
}

readonly record struct DecodeRequest(int StreamId, int Revision, int BlockIndex);

sealed record AudioBlock(
    int StreamId,
    int Revision,
    int BlockIndex,
    int Channels,
    int Frames,
    float[] Samples);

sealed class AudioStreamCommitter
{
    private readonly int channels;
    private readonly int framesPerBlock;
    private DecodeRequest currentRequest;

    public AudioStreamCommitter(int channels, int framesPerBlock)
    {
        if (channels <= 0 || framesPerBlock <= 0)
            throw new ArgumentOutOfRangeException(nameof(channels));
        this.channels = channels;
        this.framesPerBlock = framesPerBlock;
        Active = new AudioBlock(
            0, 0, -1, channels, framesPerBlock,
            new float[channels * framesPerBlock]);
    }

    public AudioBlock Active { get; private set; }

    public DecodeRequest Request(int streamId, int blockIndex)
    {
        currentRequest = new DecodeRequest(
            streamId, currentRequest.Revision + 1, blockIndex);
        return currentRequest;
    }

    public CommitResult Complete(
        DecodeRequest request,
        AudioBlock candidate)
    {
        if (request != currentRequest)
            return CommitResult.StaleRequest;
        if (candidate.StreamId != request.StreamId ||
            candidate.Revision != request.Revision ||
            candidate.BlockIndex != request.BlockIndex)
            return CommitResult.WrongStream;
        if (candidate.Channels != channels)
            return CommitResult.WrongChannelCount;
        if (candidate.Frames != framesPerBlock ||
            candidate.Samples.Length != channels * framesPerBlock)
            return CommitResult.IncompleteBlock;
        if (candidate.Samples.Any(sample => !float.IsFinite(sample)))
            return CommitResult.NonFiniteSample;

        Active = candidate with
        {
            Samples = (float[])candidate.Samples.Clone()
        };
        return CommitResult.Applied;
    }
}

cd "$LAB_DIR"
dotnet restore AudioStreamCommitLab.csproj
dotnet build AudioStreamCommitLab.csproj -c Release --no-restore
dotnet run --project AudioStreamCommitLab.csproj -c Release --no-build

Build succeeded.
    0 Warning(s)
    0 Error(s)
late_decode stream=Ambience revision=1 result=StaleRequest active_stream=20
short_voice frames=3/4 result=IncompleteBlock active_stream=20
full_voice frames=4/4 result=Applied active_stream=20 first_sample=0.75
tests pass=8 fail=0 skip=0 duration_ms=63.25