Code on Android Studio

package com.example.armorvoicemodulator;

import android.Manifest;
import android.content.pm.PackageManager;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import be.tarsos.dsp.AudioDispatcher;
import be.tarsos.dsp.io.android.AudioDispatcherFactory;
import be.tarsos.dsp.WaveformSimilarityBasedOverlapAdd;
import be.tarsos.dsp.resample.RateTransposer;
import be.tarsos.dsp.filters.BandPass;
import be.tarsos.dsp.effects.DelayEffect;
import be.tarsos.dsp.GainProcessor;
import be.tarsos.dsp.io.TarsosDSPAudioFormat;
import be.tarsos.dsp.io.android.AndroidAudioPlayer;

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_RECORD_AUDIO = 13;
    private AudioDispatcher dispatcher;
    private Thread audioThread;

    // Desired effect parameters
    private double pitchFactor = 1.0;
    private float gainFactor = 2.0f;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // No setContentView()—headless operation

        // 1) Check/request RECORD_AUDIO permission
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M
                && ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(
                    this,
                    new String[]{Manifest.permission.RECORD_AUDIO},
                    REQUEST_RECORD_AUDIO
            );
        } else {
            startAudioProcessing();  // already have permission
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_RECORD_AUDIO
                && grantResults.length > 0
                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            startAudioProcessing();
        } else {
            Log.e("VoiceModulator", "Permission denied. Exiting.");
            finish();
        }
    }

    private void startAudioProcessing() {
        // 2) Stop existing dispatcher if running
        if (audioThread != null && audioThread.isAlive()) {
            dispatcher.stop();
            audioThread = null;
            dispatcher = null;
        }

        // 3) Audio settings
        float sampleRate = 44100f;
        int sampleRateInt = (int) sampleRate;

        // Create WSOLA processor first
        WaveformSimilarityBasedOverlapAdd wsola =
                new WaveformSimilarityBasedOverlapAdd(
                        WaveformSimilarityBasedOverlapAdd
                                .Parameters.musicDefaults(pitchFactor, sampleRate)
                );

        // Retrieve buffer size and overlap from WSOLA
        int bufferSize = wsola.getInputBufferSize();
        int bufferOverlap = wsola.getOverlap();

        // 4) Create dispatcher with WSOLA's buffer size and overlap
        dispatcher = AudioDispatcherFactory.fromDefaultMicrophone(
                sampleRateInt,
                bufferSize,
                bufferOverlap
        );

        // 5) Set dispatcher for WSOLA
        wsola.setDispatcher(dispatcher);
        dispatcher.addAudioProcessor(wsola);

        // 6) Chain remaining effects
        dispatcher.addAudioProcessor(new RateTransposer(pitchFactor));
        dispatcher.addAudioProcessor(new BandPass(300f, 3000f, sampleRate));
        dispatcher.addAudioProcessor(new DelayEffect(0.09f, 0.3f, sampleRate));
        dispatcher.addAudioProcessor(new GainProcessor(gainFactor));

        // 7) Playback via AndroidAudioPlayer
        TarsosDSPAudioFormat tarsosFormat = new TarsosDSPAudioFormat(
                sampleRate, 16, 1, true, false
        );
        dispatcher.addAudioProcessor(
                new AndroidAudioPlayer(
                        tarsosFormat,
                        bufferSize,
                        AudioManager.STREAM_MUSIC
                )
        );

        // 8) Launch processing thread
        audioThread = new Thread(dispatcher, "Audio Dispatcher");
        audioThread.start();
        Log.i("VoiceModulator", "Modulator started.");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (audioThread != null && audioThread.isAlive()) {
            dispatcher.stop();
        }
    }
}