AVSpeechSynthesizer volume too low - ios

Question

I'm trying to create an app with Swift.
I integrated correctly speech-to-text and text-to-speech: my app works perfectly. You can find my project here.
After speech-to-text, the app makes an http request to a server (sending the text recognized) and the response (It is a string, i.e.: "Ok, I'll show you something") is reproduced vocally from text-to-speech. But, there is a big issue and I can't solve it.
When the app is reproducing the text vocally, the voice is too slow, as if it were in the background, as if there was something to be reproduced more important than the voice (actually nothing).
Debugging, I discovered that the issue starts using audioEngine (AVAudioEngine) inside the function recordAndRecognizeSpeech(). Running the app without using this function and playing a random text it works like a charm.
So, in my opinion when the app is reproducing the text vocally, it thinks there is still active audioengine, so the volume is very slow.
But, before reproducing the text, I called these functions (look inside ac function, line 96):
audioEngine.stop()
audioEngine.reset()
How can I solve this issue?
EDIT:
I found a partial solution. Now before the app plays the text vocally my code is:
audioEngine.inputNode.removeTap(onBus: 0)
audioEngine.stop()
audioEngine.reset()
recognitionTask?.cancel()
isRecording = false
microphoneButton.setTitle("Avvia..", for: UIControl.State.normal);
do {
let audioSession = AVAudioSession.sharedInstance()
try audioSession.setCategory(AVAudioSession.Category.ambient)
try audioSession.setActive(false, options: .notifyOthersOnDeactivation)
} catch {
print(error)
}
make_request(msg: self.speech_result.text!)
The function .setCategory works and the volume is like the default one. When I try to recall recordAndRecognizeSpeech() function, the app gives me this exception:
VAEInternal.h:70:_AVAE_Check: required condition is false: [AVAudioIONodeImpl.mm:910:SetOutputFormat: (IsFormatSampleRateAndChannelCountValid(hwFormat))]
This exception is caused by .setCategory(AVAudioSession.Category.ambient), it should be .playAndRecord, but with this value the volume returns to be low.

Answer 1

try this one.
let speaker = AVSpeechSynthesizer()
func say(text: String, language: String) {
// Start audio session
let audioSession = AVAudioSession.sharedInstance()
do {
try audioSession.setCategory(AVAudioSession.Category.playAndRecord)
try audioSession.setMode(AVAudioSession.Mode.default)
try audioSession.setActive(true)
try AVAudioSession.sharedInstance().overrideOutputAudioPort(AVAudioSession.PortOverride.speaker)
} catch {
return
}
if speaker.isSpeaking {
speaker.stopSpeaking(at: .immediate)
} else {
myUtterance = AVSpeechUtterance(string: text)
myUtterance.rate = AVSpeechUtteranceDefaultSpeechRate
myUtterance.voice = AVSpeechSynthesisVoice(language: language)
myUtterance.pitchMultiplier = 1
myUtterance.volume = 2
DispatchQueue.main.async {
self.speaker.speak(myUtterance)
}
}
}

Answer 2

Try This .
set rate for play speedly
var speedd = AVSpeechSynthesizer()
var voicert = AVSpeechUtterance()
voicert = AVSpeechUtterance(string: "Your post appears to contain code that is not properly formatted as code. Please indent all code by 4 spaces using the code toolbar button or the CTRL+K keyboard shortcut. For more editing help, click the [?] toolbar icon")
voicert.voice = AVSpeechSynthesisVoice(language: "en-US")
voicert.rate = 0.5
speedd.speak(voicert)