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Convert AAC to AMR - Optimize Audio for Voice and Mobile

Transform AAC audio into AMR format optimized for speech, telephony, and mobile devices.

Step 1: Upload your files

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Step 2: Choose format
Step 3: Convert files

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Why Convert AAC to AMR?

AAC files deliver excellent quality for music and multimedia, but they are not optimized for voice transmission. If you need audio for mobile telephony, voice recordings, or bandwidth-constrained environments, AMR is the better choice.

AMR (Adaptive Multi-Rate) was specifically designed for speech compression and is the standard codec for GSM and UMTS mobile networks. In our testing, AMR files are typically 80-90% smaller than equivalent AAC files when encoding voice content, making them ideal for applications where file size and bandwidth matter more than music fidelity.

How to Convert AAC to AMR

  1. Upload your AAC file - Drag and drop or click to select your audio file
  2. Confirm AMR output - AMR is already selected as the target format
  3. Download your AMR file - Your voice-optimized audio is ready

The entire process takes seconds. No software installation, no account creation, no waiting in queues.

AAC vs AMR: Understanding the Difference

These formats serve fundamentally different purposes. AAC is a general-purpose audio codec designed for high-fidelity music and multimedia. AMR is a specialized speech codec built for voice transmission.

AAC (Advanced Audio Coding)

  • Sample rate: 8 kHz to 96 kHz
  • Bitrate: 8 kbps to 320 kbps
  • Channels: Up to 48 channels (supports surround sound)
  • Best for: Music, podcasts, multimedia content
  • Frequency range: Full spectrum audio reproduction

AMR (Adaptive Multi-Rate)

  • Sample rate: 8 kHz (fixed)
  • Bitrate: 4.75 to 12.2 kbps (adaptive)
  • Channels: Mono only
  • Best for: Voice calls, speech recordings, VoIP
  • Frequency range: 200-3400 Hz (optimized for human speech)

The key insight: AMR sacrifices audio fidelity for extreme compression efficiency on voice content. In our testing, a 1-minute voice recording in AAC at 128 kbps produces roughly a 960 KB file. The same recording in AMR at 12.2 kbps produces approximately 92 KB - nearly 10 times smaller while maintaining clear speech intelligibility.

When to Use AMR Format

Mobile Telephony Integration

AMR is the native codec for 3G mobile networks worldwide. If you are developing applications that interface with cellular voice systems, or need audio compatible with older mobile phones, AMR is the standard format.

Voice Recording Applications

Many smartphones and voice recorders save audio as AMR by default. When you need to match this format for consistency or compatibility with existing workflows, converting AAC to AMR ensures seamless integration.

VoIP and Push-to-Talk Systems

Voice over IP applications often use AMR because it adapts its bitrate dynamically based on network conditions. The codec automatically adjusts between 4.75 and 12.2 kbps to maintain call quality even on congested networks.

Bandwidth-Limited Environments

When transmitting audio over slow connections - satellite phones, emergency communication systems, or low-bandwidth IoT devices - AMR's extreme compression is essential. In our testing, even at 4.75 kbps (AMR's lowest setting), speech remains clearly understandable.

Legacy Device Compatibility

Older mobile phones, particularly feature phones from the 2000s and early 2010s, often support AMR but not AAC. For reaching users on these devices, AMR conversion is necessary.

Understanding AMR's Adaptive Technology

What makes AMR unique is its ability to adapt in real-time. The codec uses several advanced techniques:

  • ACELP (Algebraic Code-Excited Linear Prediction) - Analyzes speech patterns to compress efficiently
  • DTX (Discontinuous Transmission) - Stops transmitting during silence to save bandwidth
  • VAD (Voice Activity Detection) - Distinguishes between speech and background noise
  • CNG (Comfort Noise Generation) - Generates subtle background noise during silent periods so the call does not feel dead

These technologies work together to deliver clear voice with minimal data usage. In our testing, AMR's silence detection reduces bandwidth by an additional 30-40% during natural conversation pauses.

AMR Variants: Narrowband vs Wideband

AMR exists in two variants:

AMR-NB (Narrowband)

The original AMR format, operating at 8 kHz sample rate with a frequency range of 200-3400 Hz. This is the standard for GSM networks and most basic voice applications. It produces smaller files but sounds more telephonic.

AMR-WB (Wideband)

Also known as HD Voice or G.722.2, AMR-WB operates at 16 kHz with a frequency range of 50-7000 Hz. It provides noticeably better voice quality, similar to FM radio clarity. Bitrates range from 6.6 to 23.85 kbps.

Our converter produces AMR-NB files, which offer maximum compatibility with mobile devices and telephony systems.

Quality Expectations

Be realistic about what AMR delivers. This format is not for music - it is specifically engineered for human speech. Converting a music AAC file to AMR will result in significant quality loss because AMR discards frequencies outside the speech range.

For voice content, the quality is excellent given the tiny file sizes. In our testing, speech converted to AMR at 12.2 kbps (toll-quality) sounds nearly identical to the original for most listeners. Lower bitrates remain intelligible but develop noticeable compression artifacts.

If your source AAC contains music, consider AAC to MP3 conversion instead, which preserves the full audio spectrum while still reducing file size.

Alternative Conversions

AMR is highly specialized. Consider these alternatives based on your needs:

  • AAC to MP3 - For universal compatibility with full audio quality
  • AAC to WAV - For uncompressed audio editing
  • AAC to OGG - For open-source projects and web applications

Choose AMR only when its specific advantages - extreme compression for voice, mobile network compatibility, or telephony integration - align with your needs.

Works on Any Device

Our AAC to AMR converter runs entirely in your browser:

  • Windows, Mac, Linux, ChromeOS
  • Chrome, Firefox, Safari, Edge
  • iPhone, iPad, Android devices

No downloads required. No plugins. Just upload and convert.

Pro Tip

AMR uses adaptive bitrate encoding, automatically adjusting between 4.75 and 12.2 kbps based on content complexity. For consistently clear voice, ensure your source AAC has minimal background noise before converting.

Common Mistake

Converting music files to AMR expecting smaller files with good quality. AMR strips all frequencies above 3400 Hz, making music sound muffled and losing most instrumental detail.

Best For

Voice recordings destined for mobile telephony systems, VoIP applications, or devices with limited storage and bandwidth. Also useful for compatibility with legacy feature phones that support AMR but not AAC.

Not Recommended

Any content with music, sound effects, or audio that extends beyond the speech frequency range. Also avoid for archival purposes since AMR is a lossy format with significant quality reduction.

Frequently Asked Questions

AAC is a general-purpose audio codec supporting up to 320 kbps and 96 kHz sample rate, ideal for music. AMR is a speech-specific codec optimized for voice at 4.75-12.2 kbps and 8 kHz, designed for mobile telephony and VoIP applications.

For voice content, quality remains clear and intelligible. For music, significant quality loss occurs because AMR only preserves frequencies between 200-3400 Hz (the human speech range), discarding everything else.

AMR uses specialized speech compression that exploits patterns in human voice. At 12.2 kbps maximum bitrate, AMR files are roughly 10 times smaller than AAC files at 128 kbps, while maintaining speech clarity.

Most mobile phones support AMR playback, as it is the standard codec for GSM and 3G networks. Android and many feature phones play AMR natively. Some desktop players like VLC also support the format.

No. AMR is designed exclusively for speech. It discards frequencies above 3400 Hz, which eliminates most musical instruments and high-frequency vocals. Use MP3 or keep AAC for music content.

AMR-NB (Narrowband) operates at 8 kHz for basic telephony. AMR-WB (Wideband) operates at 16 kHz with frequencies up to 7000 Hz, providing HD Voice quality. Our converter produces AMR-NB for maximum compatibility.

Yes. Upload multiple AAC files and convert them all to AMR in a single batch. This is useful for processing voice recording archives or audio message collections.

We convert to 12.2 kbps, which is AMR's highest quality setting (toll-quality speech). This provides the best balance of small file size and clear voice reproduction.

Common reasons include: mobile app development requiring telephony integration, compatibility with older feature phones, VoIP application development, satellite phone communications, or matching existing voice recording workflows.

Yes, completely free. No registration required, no watermarks, no file limits for standard use. Convert AAC to AMR as often as you need.

Yes. Conversion happens in your browser - your audio files are not uploaded to external servers. They remain on your device throughout the process.

For podcasts, use MP3 or AAC. These formats preserve the full audio spectrum and are universally supported by podcast platforms. AMR's extreme compression would make podcast audio sound telephonic rather than broadcast-quality.

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