SFSpeechRecognizer - detect end of utterance

Question

I am hacking a little project using iOS 10 built-in speech recognition. I have working results using device\'s microphone, my speech is recognized very accurately.

M

Answer 1

Based on my test on iOS10, when shouldReportPartialResults is set to false, you have to wait 60 seconds to get the result.

Answer 2

It seems that isFinal flag doesn't became true when user stops talking as expected. I guess this is a wanted behaviour by Apple, because the event "User stops talking" is an undefined event.

I believe that the easiest way to achieve your goal is to do the following:

• You have to estabilish an "interval of silence". That means if the user doesn't talk for a time greater than your interval, he has stopped talking (i.e. 2 seconds).

• Create a Timer at the beginning of the audio session:

var timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: "didFinishTalk", userInfo: nil, repeats: false)

• when you get new transcriptions in recognitionTaskinvalidate and restart your timer

  timer.invalidate() timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: "didFinishTalk", userInfo: nil, repeats: false)

• if the timer expires this means the user doesn't talk from 2 seconds. You can safely stop Audio Session and exit

Answer 3

I am using Speech to text in an app currently and it is working fine for me. My recognitionTask block is as follows:

recognitionTask = speechRecognizer?.recognitionTask(with: recognitionRequest, resultHandler: { (result, error) in
        var isFinal = false

        if let result = result, result.isFinal {
            print("Result: \(result.bestTranscription.formattedString)")
            isFinal = result.isFinal
            completion(result.bestTranscription.formattedString, nil)
        }

        if error != nil || isFinal {
            self.audioEngine.stop()
            inputNode.removeTap(onBus: 0)

            self.recognitionRequest = nil
            self.recognitionTask = nil
            completion(nil, error)
        }
    })

Answer 4

if result != nil {
    self.timerDidFinishTalk.invalidate()
    self.timerDidFinishTalk = Timer.scheduledTimer(timeInterval: TimeInterval(self.listeningTime), target: self, selector:#selector(self.didFinishTalk), userInfo: nil, repeats: false)

    let bestString = result?.bestTranscription.formattedString

    self.fullsTring =  bestString!.trimmingCharacters(in: .whitespaces)
    self.st = self.fullsTring
  }

Here self.listeningTime is the time after which you want to stop after getting end of the utterance.