Increase the audio input level

- (void) configureAudioSession
{

    AVAudioSession* session = [AVAudioSession
                               sharedInstance];

    // Don't activate the audio session yet
    [session setActive:NO error:NULL];

    // Play music even in background and dont stop playing music
    // even another app starts playing sound
    [session setCategory:AVAudioSessionCategoryRecord error:NULL];

    double sampleRate = 16000.0;
    [session setPreferredSampleRate:sampleRate error:NULL];

    // Active the audio session
    [session setActive:YES error:NULL];
}

- (void) initMic {
    [self configureAudioSession];
    AudioStreamBasicDescription audioStreamBasicDescription = [EZAudioUtilities monoFloatFormatWithSampleRate:16000];
    audioStreamBasicDescription.mFormatID = kAudioFormatLinearPCM;
    audioStreamBasicDescription.mSampleRate = 16000.0;
    audioStreamBasicDescription.mFramesPerPacket = 1;
    audioStreamBasicDescription.mBytesPerPacket = 2;
    audioStreamBasicDescription.mBytesPerFrame = 2;
    audioStreamBasicDescription.mChannelsPerFrame = 1;
    audioStreamBasicDescription.mBitsPerChannel = 16;
    audioStreamBasicDescription.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;
    audioStreamBasicDescription.mReserved = 0;

    NSArray *inputs = [EZAudioDevice inputDevices];
    [self.microphone setDevice:[inputs lastObject]];
    self.microphone = [EZMicrophone microphoneWithDelegate:self withAudioStreamBasicDescription:audioStreamBasicDescription];
    [self.microphone startFetchingAudio];
}

-(void) microphone:(EZMicrophone *)microphone
  hasAudioReceived:(float **)buffer
    withBufferSize:(UInt32)bufferSize
withNumberOfChannels:(UInt32)numberOfChannels {
    dispatch_async(dispatch_get_main_queue(),^{
        int result = _snowboyDetect->RunDetection(buffer[0], bufferSize);
        if (result >= 1) {
             NSLog(@"Hotword Detected");
            NSString *modelName = modelsList[result - 1];
            NSDictionary *jsonObj = @{@"message":@"Hotword Detected",@"modelname": modelName};
            [self triggerJSEventData:jsonObj];
           // [self triggerJSEvent:@"Hotword Detected"];
            detection_countdown = 30;
        } else {
            if (detection_countdown == 0){
                NSLog(@"No Hotword Detected");
                [self triggerJSEvent:@"No Hotword Detected"];
            } else {
                detection_countdown--;
            }
        }
    });
}

I use EZAudio which is working with Snowboy Hotword Detection. On Android the Hotword ist recognizing perfectly, even if I speak quiet. With ios the Hotword is not recognized if I speak very quietly. Now my question: Is it possible to increase the microphone level on IOS? I have a feeling it's related to that. Is there any way to increase the mic input level?

syedhali / EZAudio

Increase the audio input level #381