const transcription = await nodewhisper(audioPath, {
        modelName: 'base.en',
        responseFormat: 'json'
    }); // returns JSON object

import fs from 'fs';
import path from 'path';
...
await nodewhisper(audioPath, {
        modelName: 'base.en',
        whisperOptions: {
            outputInJson: true
        }
 });
const response = fs.readFileSync(`${path.join(path.dirname(audioPath), path.basename(audioPath, path.extname(audioPath)))}.wav.json`, 'utf8');
const transcription = JSON.parse(response);