We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Adaptive Multi-Rate (AMR)?

By Sheri Cyprus
Updated May 16, 2024
Our promise to you
EasyTechJunkie is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At EasyTechJunkie, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Adaptive Multi-Rate (AMR) is used in speech coding and involves audio data compression. Audio data compression allows for more storage on voice files. ".amt" is a popular filename extension for AMR. Many cell phones use AMR for speech recording storage.

AMR is especially associated with the Global System for Mobile Communications (GSM). GSM, a circuit-switched system, originated in Europe in the 1980s and is used in many European countries. Several cellular companies in the United States and other non-European countries also use GSM technology.

Speech coding uses a circuit speech codec, or voice codec, that digitally transforms speech. Music can be encoded and decoded in a voice codec, but the quality of the music produced is usually quite poor. The speech or voice codec is specifically made to analyze human speech rather than to offer quality sound in other audio forms such as music.

AMR used in cellular technology is said to provide the highest quality of speech clarity for remote mobile phone communication at the lowest possible cost. AMR is thought to be a very adaptable speech codec for many different radio channels. The AMR can adjust itself by providing extra bits to help correct errors when the channel conditions are bad, while still providing only a minimum amount of bits during good channel conditions. This quality means that the AMR has more bits available for speech coding than other speech codecs.

AMR is not the first voice codec used for GSM, but the fourth. The Enhanced Full-Rate (EFR) codec and the other two speech codecs differ from AMR as they can not adjust their rate of bits produced. AMR is said to offer the best voice quality of the four speech codecs. Cellular telephone manufacturers continue to develop AMR codec technology by striving for the most natural sounding voice quality possible. These manufacturers often conduct consumer tests to test for the clearest sounding voice transmission on cellular phones.

Voice Activity Detection (VAD), Comfort Noise Generation (CNG) and Discontinuous Transmission (DTX) are some important features of AMR. VAD differentiates speech from silence to aid in speech processing and the VAD in AMR helps improve the quality of speech coding. CNG is low-level background static added on purpose to help minimize some negative effects of silence such as sudden swings in sound levels from voice to silence. DTX technology controls the transmitter switch during wireless conversations so that the battery or amplifiers are not used unnecessarily during silent periods when there is no speech.

EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By miriam98 — On Jul 11, 2011

I have a cell phone that stores its voice files in the .amr format. I was able to download an amr converter and convert those files to mp3 format, for listening to on my computer or mp3 player.

I’ve found this to be very useful when I’m traveling and talking with clients about important business agenda items I need covered for an upcoming meeting. I have real bad memory sometimes and my phone lets me store the conversations in .amr format for listening to later.

Sometimes, however, I don’t want to hear them on my phone but would prefer to transfer them to my mp3 player, where I can organize them in folders and sort them to my liking.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.