How to set a time limit for speech recognition in ACS?

Question

I want to set a limit to the time a caller has to describe their problem after StartRecognizing has started.

I tried to implement this using CancellationToken, but it didn't work, and CancelAllMediaOperations doesn't seem to be effective either. Here is my code:

// Configure the recognition options
var recognizeOptions = new CallMediaRecognizeSpeechOptions(caller)
{
    Prompt = playSource,
    EndSilenceTimeout = TimeSpan.FromMilliseconds(1000),
    OperationContext = operationContext,
    SpeechLanguage = "de-DE"
};
timerDebug.Start();
using (var cts = new CancellationTokenSource())
{
    cts.CancelAfter(TimeSpan.FromSeconds(10));
    try
    {
        // Start recognizing speech and return the result
        StartRecognizingCallMediaResult result = await callMedia.StartRecognizingAsync(recognizeOptions, cts.Token);
        result.WaitForEventProcessor(cts.Token);
    }
    catch(OperationCanceledException ocex)
    {
        logger.LogError($"RecognizeOpenQuestion() cancelled -> {ocex.Message}");
        await callMedia.CancelAllMediaOperationsAsync(cts.Token);
    }
    catch (Exception ex)
    {
        logger.LogError($"RecognizeOpenQuestion() error -> {ex.Message}");
    }
}

Is it possible?