If your cat's voice suddenly becomes hoarse, it may be due to the following reasons, and you can try the following methods:

Observe the environment: Ensure the cat's living environment is quiet and comfortable, and avoid noise stimulation.
Make sure you drink plenty of water: Staying hydrated helps keep your throat moist.
Dietary adjustments: Avoid feeding your child spicy or irritating foods.
Rest: Provide the cat with a quiet place to rest.
Avoid excessive meowing: Reduce instances of excessive meowing in cats.
Check the throat: Check the cat's throat for any foreign objects.
Keep the air humid: Use a humidifier to increase air humidity.
Avoid stress: Reduce stressors such as strangers, new environments, etc.
Observe the cat's breathing: Observe whether the cat's breathing is normal.
If necessary, seek medical attention: If symptoms persist or worsen, it is recommended to take your cat to a veterinarian for examination to determine if there is any disease or other problem.
When dealing with a cat's hoarse voice, pay attention to other symptoms such as difficulty breathing, coughing, and drooling. If these symptoms appear, seek veterinary care as soon as possible.