Is Speech-to-Text Safe? What Happens to Your Audio Files

When you upload an audio file to a transcription service, where does it go? Is your data safe? These questions matter—especially when your recordings contain sensitive conversations, business meetings, or personal information.

This article is part of our speech-to-text privacy and compliance guide. Here, we focus specifically on what happens to your audio files during and after transcription.

Why Audio Data Is Sensitive

Audio recordings are more than just sound waves. Under regulations like GDPR, voice recordings qualify as personal data for two reasons:

1. Your voice is biometric data. Voice recognition technology can identify you uniquely—similar to fingerprints or facial recognition. Unlike passwords, you cannot change your voice if it gets compromised.

2. Content may contain personal information. Depending on what you recorded, transcripts might include names, addresses, financial details, health information, or confidential business discussions.

This dual sensitivity means transcription services must handle your files with extra care.

How Speech-to-Text Services Process Your Audio

Most transcription services follow a similar workflow:

During Processing

• Real-time transcription: Audio is processed in server memory and typically not stored. Major providers like Google and Microsoft process streaming audio without writing it to disk.

• Batch transcription: Your file uploads to the provider's servers, gets processed, and the transcript is generated. The key question is what happens next.

After Processing

This is where services differ significantly:

• Some delete immediately: Providers like Google's Speech-to-Text API process audio in memory for sync requests and don't store it afterward.

• Some retain temporarily: Services may keep files for a few days to allow transcript retrieval. For example, Google's async endpoint stores transcripts for approximately 5 days.

• Some retain longer: Other services may keep recordings for quality assurance, model training, or until you manually delete them.

Always check a provider's data retention policy before uploading sensitive content.

Encryption: The First Line of Defense

Reputable transcription services use encryption at two stages:

In Transit

When your file travels from your device to the server, TLS (Transport Layer Security) encryption protects it from interception. Look for services that use TLS 1.2 or higher.

At Rest

If your files are stored (even temporarily), AES-256 encryption should protect them. This is the same standard used by banks and government agencies. Services like Rev, Otter.ai, and major cloud providers encrypt stored data with AES-256.

What to verify: Ask whether encryption covers both transmission and storage. Some free services may encrypt only during transfer.

What Gets Stored (And Who Can Access It)

Beyond encryption, consider these access questions:

Storage Location

Most services use cloud infrastructure (AWS, Google Cloud, Azure). Enterprise services may offer region-specific storage for compliance with data residency requirements.

Access Controls

Professional services implement:

• Role-based access: Only authorized personnel can access customer data
• Non-disclosure agreements: Employees sign NDAs before handling content
• Audit logging: Systems track who accessed what and when

Human Review

Some services use human transcriptionists for accuracy or quality review. If privacy is critical, ask whether humans will see your content or if processing is fully automated.

AI Training: Is Your Audio Used to Improve Models?

A common concern: will your recordings train someone else's AI?

Transparent providers explicitly state their policies:

• Opt-in programs: Services like Google offer data logging programs that you can choose to join
• No training guarantees: Many enterprise services, including Rev and AssemblyAI, explicitly state they don't use customer data for model training
• Anonymization: If data is used for improvement, it should be anonymized and aggregated

Red flag: If a service's privacy policy doesn't clearly address AI training, assume your data might be used.

Deleting Your Data

You should be able to remove your content. Check for:

• Self-service deletion: Can you delete files from your account dashboard?
• Automatic deletion: Can you set retention periods (e.g., delete after 30 days)?
• API deletion: For developers, are there programmatic deletion endpoints?
• Full purge: Does deletion include backups and logs, or just the primary copy?

Services compliant with GDPR must honor deletion requests within a reasonable timeframe.

Questions to Ask Any Transcription Provider

Before uploading sensitive audio, get answers to:

1. Where are files stored geographically?
2. How long are recordings retained after transcription?
3. Is processing automated, or do humans review content?
4. Is my data used to train AI models?
5. What encryption standards protect files in transit and at rest?
6. Can I delete my data, and is deletion complete?
7. What compliance certifications does the service hold (SOC 2, HIPAA, GDPR)?

Practical Tips for Safer Transcription

Regardless of which service you choose:

• Avoid sharing passwords or financial details in recordings you'll transcribe
• Review retention policies before uploading confidential content
• Delete files after downloading your transcript if the service allows
• Consider on-device options for the most sensitive content (some tools process locally without cloud upload)

Conclusion

Speech-to-text services can be safe—but "safe" depends on the provider's practices and your use case. Encryption, clear retention policies, access controls, and transparent AI training policies are the hallmarks of trustworthy services.

For everyday transcription of meetings, interviews, or content creation, reputable cloud services provide adequate protection. For highly sensitive material, verify policies carefully or consider tools that process audio locally.

Tools like Scriby offer straightforward transcription with pay-as-you-go pricing and clear data handling—no subscriptions or complex compliance reviews needed. You stay in control of what you upload and when you delete it.